Distributed in North America, from the Isthmus of Panama to the southern provinces of Canada. Its acclimatization was carried out in Germany and the Soviet Union (most successfully in the south of Belarus and Azerbaijan); From the release points, the raccoon moved to France and other European countries.

Body length 45-60 cm, tail 20-25 cm; weight 5-9 kg.

Mixed forests with old hollow trees and the presence of ponds or swamps are most suitable for the striped raccoon. Coniferous forests, like forests devoid of reservoirs, he avoids. In the south of the range it is found on sea ​​coast. Raccoons easily adapt to the anthropogenic landscape, settling on the outskirts of fields, in gardens, and are often found in cities and suburbs. The raccoon makes its home (often several) in hollows, sometimes at a height of 20-30 meters above the ground. As a last resort, it uses ground shelters - crevices in rocks, badger holes; He doesn’t know how to dig holes himself. Leads twilight night image life; spends daytime hours in the den. It goes fishing at dusk, walking around its area (with a radius of up to 1.5 km) in search of food.

The striped raccoon deftly climbs trees; very tenacious fingers allow it to hang, clinging to a horizontal branch, or go down the trunk upside down. Thanks to excellent night vision and vibrissae, tufts of which are located not only on the head, but also near the claws, on the inside of the limbs, on the chest and stomach, the raccoon moves confidently even in complete darkness. Raccoons swim well, although reluctantly.

The raccoon is omnivorous. Its diet shows a seasonal change in food. In spring and early summer, the basis of its diet is animal feed; in the second half of summer and autumn he prefers plant foods. The raccoon's main animal food is insects and frogs, less commonly reptiles (snakes, lizards), crayfish and crabs, fish, rodents and bird eggs. The plant diet consists of berries, acorns, nuts and fruits. Before eating, a raccoon sometimes rinses its food in water. If raccoons live near people, they will readily rummage through garbage.

The raccoon is a very resilient animal. It is immune to many infectious and invasive diseases and aggressively defends itself against predators. Raccoons are attacked by coyotes, wolves, bobcats, elks, alligators, owls; on the cubs - snakes. If a raccoon cannot hide or escape, it will play dead. By nature, this animal is active, very curious, pugnacious, brave and cunning.

The rut occurs in February-March, pregnancy lasts 63 days. The female brings 3-7 cubs, which mature on the 18-20th day. In August-September, at the age of 4-5 months, young raccoons become independent, but sometimes the brood remains with the mother until winter. Females reach sexual maturity at one year of age.

Life expectancy is up to 12-16 years, but, as a rule, they live no more than 2-5 years.

Cozumel raccoon

Cozumel Raccoon

(Procyon pygmaeus)

Distributed only on the island of Cozumel, which is located near the coast of the Mexican Yucatan Peninsula. Inhabits mangrove forests and wetlands in the northwestern part of the island. The population density is approximately 17-27 individuals per km 2.

The body weight of this raccoon is 3-4 kg.

This is an omnivore. Crabs make up about 50% of the total diet, with the rest coming from fruits, frogs, lizards and insects. During the rainy season, more plant foods are consumed; during the dry season, crabs, lizards, and insects are consumed.

Raccoon-eater

Crab-eating Raccoon

(Procyon cancrivorus)

Distributed in South America, from Costa Rica to northern Argentina: Bolivia, Brazil, Colombia, Paraguay, Uruguay, Costa Rica, Guyana, Panama, Peru, Suriname, Trinidad and Tabago and Venezuela.

The head and body are from 41 to 60 cm in length, the tail length is from 20 to 42 cm, the height at the withers is about 23 cm, and the body weight ranges from 2 to 12 kg. Males are usually larger than females.

It prefers to settle in swampy and wooded coastal areas near seas, lakes and rivers, where it is mainly found among shrub and tree vegetation, usually near water. Raccoons live both on the ground and in trees. Activities are primarily nocturnal; they climb trees and swim well in water. The crab-eating raccoon has relatively very high intellectual abilities. According to a number of indicators, raccoons were placed above cats, but below primates. It has been established that raccoons can learn quickly and are able to retain knowledge for up to a year.

They spend the day in their dens. Raccoons living in wooded areas make their dens in a hollow log, stump or tree, or dens left by other animals. In the area where humans live, they can set up shop in an abandoned barn or farmhouse. In swampy, treeless areas, raccoons make a nest in tall grass and, on occasion, occupy a muskrat's den.

Male raccoons lead a solitary lifestyle within their hunting grounds, which they protect from other males. The size of this feeding area can be about 40-100 hectares. The areas of individual raccoons can only partially overlap in individuals of different sexes.

It feeds on crabs, lobsters and other crustaceans, but they are omnivores and their diet also includes, for example, small amphibians, turtle eggs and fruit.

Reproduction occurs once a year, and breeding occurs from July to September. Males may mate with several females during the mating season, and females reject other males as soon as they are fertilized. The estrus cycle usually lasts between 80-140 days.

After 60-73 days of gestation, females give birth 2-7; on average - 3-4 cubs. The female makes her lair in crevices among stones, hollow trees, or in abandoned lairs of other animals. Newborns are born without teeth and with eyes closed. Babies weigh about 71 grams at birth. After 3 weeks, their eyes are already open and the characteristic colors of a raccoon appear on their faces.

Guadalupe raccoon

Guadeloupe Raccoon

(Procyon minor)

It is found on the island of Guadeloupe, located in the Caribbean Sea.

Body length - 50-60 cm. Weight - from 2.5 kg and more, up to 15 kg.

The habitat of the Guadalupe raccoon is wet and dry forests, swampy mangrove coastal forests with free access to open water (rivers or other bodies of water).

Leads a nocturnal lifestyle. During the day he sleeps in empty tree trunks or on branches in the shade of leaves. The raccoon is an excellent swimmer and can catch prey in the water. Before eating his prey, he washes it in water. It is an omnivore: it eats meat food, fish, and eats fruits. The diet is based on small mammals, including rodents, mollusks, invertebrates (mainly insects), some reptiles and amphibians.

Breeding period: January-March. Pregnancy lasts about 2 months. The female gives birth to 2-5 babies. Lactation lasts up to 2-4 months.

The genus (Procyon) also includes: Tremarias raccoon (Procyon insularis), Barbados raccoon (Procyon gloveralleni), Bahamian raccoon (Procyon maynardi). In terms of lifestyle and appearance, they are very close to the striped raccoon. There is still a debate among scientists about the question: are these raccoons actually separate independent species, or are they just subspecies of Procyon lotor.

Kakomitsli

Ringtail

(Bassariscus astutus)

Common in the south North America(from southern Oregon to New Mexico) in dry, rocky areas, canyons, mountain coniferous forests, semi-deserts.

Body length up to 38 cm, tail - up to 44 cm, shoulder height - up to 16 cm; weight up to 1.3 kg.

Leads a nocturnal lifestyle. Very good at climbing trees and rocks; settles in hollows, among stones and in ruins. Omnivore, but prefers protein foods. Feeds on rodents, rabbits, squirrels and insects; less often it catches birds, lizards and snakes, frogs and eats carrion. Among plant foods, it eats acorns, juniper berries, persimmons and other fruits; nectar.

Solitary lifestyle. One male occupies a hunting territory of up to 136 hectares; The territories of some people of the same sex do not intersect. The female gives birth to 1-4 cubs in May - June. Young animals reach sexual maturity at 10 months.

Central American kakomitsli

Cacomistle

(Bassariscus sumichrasti)

Distributed in Central America (Belize, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama).

Body length 380-470 mm, tail - 390-530 mm. Height at withers up to 17 cm. Weight on average 900 g.

Inhabits humid, evergreen tropical woodlands and mountain forests up to 2000 m above sea level. Occasionally found in drier deciduous forests, where it may migrate during the wet season. Excellent tree climber. It settles in hollows of trees, among stones, in abandoned and destroyed buildings and houses. This is a nocturnal arboreal animal that almost never descends to the ground. Thanks to its claws, it climbs trees and branches well. Long tail used for balancing.

This is an omnivore. In summer it feeds mainly on plants (preferring papaya and bananas). Also eats insects, bird eggs and the chicks themselves, tree frogs and lizards.

Cacomitsli are solitary animals, but sometimes small feeding groups (up to five to nine individuals) can be found in fruit trees. At the same time, aggressive behavior may be observed between some people, and clashes may occur. They are territorial animals. The territory of one individual can occupy up to 136 hectares. They do not mark the boundaries of their territory. The animals exchange loud calls among themselves, presumably to mark territorial boundaries.

Breeding season: February-June. Estrus lasts for 44 days, but only one day the female is ready to conceive. Pregnancy lasts 63-66 days. The nest or den is made in tree hollows. The female gives birth to 2-4 cubs. Newborns are blind, deaf and toothless, weighing about 25 grams. Eyes open on day 34. Puppies switch to solid food at 6-8 weeks of age. Lactation lasts up to three months. The female takes care of the offspring, however, sometimes the male also participates in education (games and communication). Puberty occurs at about 10 months of age.

White-nosed coati

White-nosed Coati

(Nasua narica)

It lives in the forests of southwestern North, Central and South America. It is found from southeastern Arizona through Mexico and Central America to western Colombia and Ecuador - from subtropical and lowland tropical forests to arid high-altitude forests. The nosoha lives in deserted fields and in sparse wooded areas, but usually stays near water (up to 3500 meters above sea level).

Body length is 80-130 cm, almost half of it is on the tail: body length is 41-67 cm, tail - 32-69 cm. Height at withers is 20-29 cm. Weight on average is 3-5 kg. Males are almost twice as large as females.

Adult male white-nosed coatis are active both at night and during the day, but other animals are diurnal. Often, adult coatis climb into a shady place during hot daylight hours and wait out the heat there. Young coatis are very playful and spend a lot of time noisily wrestling with each other.

Coatis spend the night in treetops, where they find shelter from most predators. They climb trees well, balancing and “holding onto” branches with their tail. They spend most of their active time looking for their main food - insects. They feed mainly on the ground. While feeding, they rummage through the litter with their mobile nose, snoring loudly and blowing up the leaves, looking for beetles, spiders, scorpions, ants, termites, various larvae, centipedes and even land crabs. They sometimes encounter small vertebrates such as rodents, lizards and frogs. When hunting them, the coati pins them to the ground with its paw and then kills them with a bite to the head. In search of food, it can travel within one day over distances of up to 2 km. When abundant plant food (especially ripe fruit) is available, coatis feed on it with visible pleasure. It is not uncommon for them to return to the fruiting tree over a long period of time.

Unlike other species of this family, the white-nosed coati lives not only alone, but also in groups of 5-6 and even up to 40 individuals. All females and young males usually live in one large family group. Adult, sexually mature single males join such a group only for the breeding season, and then they again leave their fellow tribesmen.

Solitary males usually establish the boundaries of their territory, marking them by spraying urine, or rubbing their bellies on the surface of various substrates, applying the secretions of the anal glands to them. Compared to other Carnivora species, the anal glands of the noses are modified. They have a glandular area located along the upper edge of the anus and it consists of a series of pouches that open with 4 or 5 slits on the sides. The males' territories are partially not covered and they always engage in a fight when another mature male invades them. In territorial conflicts, males use their sharp claws and fangs.

Family groups, including up to 20 individuals or more, usually consist of sexually mature females and their young, including young males up to about two years of age. Family home plots are approximately 1 km in diameter and partially overlap at the edges with plots of other groups. The home range of one family group also includes the territory of several adult males.

In February or March, males, when females are in heat, join female family groups. During this period, males enter into active struggle among themselves over females. They warn the competing male by baring their teeth, rising on their hind legs and raising the end of their muzzle upward. Only the most dominant and strong male will remain in the territory of the family group and only he will be allowed to get close to the females. Soon after the mating period ends, the male is expelled from the group because he is often aggressive towards the babies.

Breeding season: January-March. Pregnancy lasts 77 days. The white-nosed coati gives birth to cubs once a year. Usually there are 2-6 cubs in a litter. Newborns weigh 100-180 grams and are completely dependent on the mother, who leaves the nest for a while to find food. The eyes open at approximately 11 days. The babies remain in the nest for several weeks, and then leave it with their mother and join the family group. Lactation lasts up to four months. Young noses stay with their mother until she begins to prepare for the birth of the next offspring.

South American coati

South American Coati

(Nasua nasua)

It is found in the tropical regions of South America: from Colombia and Venezuela to Uruguay, northern Argentina, and it is also found in Ecuador. Coatis range from scrubland to primary evergreen rain forest. They can also be found in lowland forests, wooded riverine areas, dense bushes and rocky areas. On the eastern and western slopes of the Andes mountains they are found up to 2500 meters above sea level.

Body length is 73-136 cm (average 104.5 cm). Tail length - 32-69 cm. Height at withers 30 cm. Weight - 3-6 kg (average 4.5 kg).

They are usually active during the day. Animals spend most of their active time foraging for food, and at night they sleep in trees, which also serve to make a den and give birth to offspring. When coatis are threatened on the ground, they run into the trees; when predators threaten in a tree, they easily run to the end of the branch of one tree, and then jump to the bottom branch of the same or even another tree.

The breeding season is from October to March, with young ones born in April to June. Puberty occurs in females at 2 years, in males - about 3 years. Pregnancy lasts 74-77 days.

The South American coati usually produces 3-7 (average 5) babies in a litter. The female gives birth to her offspring in a den, which she builds in isolated tree hollows, during which time she leaves her social group. Newborn cubs are helpless: they have no fur, they are blind and weigh only 75-80 grams. The eyes open at about 10 days. At 24 days of age, young coatis can walk and focus their eyes. At 26 days, the cubs are able to climb; they switch to dense food at the age of 4 months. When the cubs are five to six weeks old, the female returns to her family group.

By type of diet, South American coatis are omnivores; their diet is based on fruits and invertebrates. They also eat eggs, beetle larvae and other insects, scorpions, centipedes, spiders, ants, termites, lizards, small mammals, rodents, and even carrion when it is available to them.

Mountain coati

Mountain Coati

(Nasuella olivacea)

It is found only in the Andean valleys of northwestern South America, inhabiting northern Peru, western Venezuela, Colombia and Ecuador. In recent years, mountain coatis have appeared in the southern United States. They settle in mountain forests at altitudes of 2000-3000 m above sea level.

They reach a length of 36-40 cm; tail - 20-24 cm. The average weight of an adult is about 7.26 kg.

Little is known about the behavior and ecology of the mountain coati.

Kinkajou

Kinkajou

(Potos flavus)

Found in rain forests in southern North America (Southern Mexico), Central and South America (south to Mato Grosso in Brazil).

Kinkajou body length is 41-57 cm, tail - 40-55 cm, shoulder height - 25 cm, weighs 1.5-2.7 kg.

Kinkajou spend their lives in trees. During the day they hide in hollows, and at night, alone or in pairs, they move along tree branches to feed, displaying speed and dexterity of movements. It feeds mainly on fruits, nectar and honey. In addition to fruits, it eats insects, frogs, lizards, bird eggs and small animals.

The social structure of the kinkajou is unusual among mammals. A typical family consists of a female, two males, a juvenile and a cub; they sleep together and groom each other, but feed separately. Unlike most other mammals, at about the age of two and a half years, females leave the family. The territory passes from father to sons, males are more closely related to each other.

Pregnancy lasts 112-118 days. The female brings 1, occasionally 2 blind cubs in spring or summer. The cubs have silver-gray fur. Sexual maturity for males occurs at 1.5 years, for females at 2.5 years. Life expectancy is about 23 years.

Olingo Gabby

Bushy-tailed Olingo

(Bassaricyon gabbii)

It is found from Nicaragua to Bolivia; in some parts of its range it is common and abundant, in others it is rare (for example, in the western part of the Amazon basin). Recorded in Colombia, Costa Rica, Ecuador, Nicaragua, Bolivia, and Panama.

Body length - 350-470 mm, tail - from 400 to 480 mm. Body weight - 970-1500 g.

The olingo's habitat is evergreen tropical forests (up to an altitude of 2000 m above sea level). It is found both in the forest itself and on the edges.

Eats a wide variety of foods. The basis of the diet is the fruits of fruit trees, nectar and juice, flowers, insects, as well as all kinds of small vertebrates. Actively hunts warm-blooded animals: birds (eats both their eggs and chicks); mammals; as well as amphibians and reptiles.

Leads a predominantly arboreal nocturnal lifestyle. Olingos spend the entire day in a nest made of dry plants and located in the trunk of a hollow tree. Agile, climbs trees, makes big jumps, easily traveling through the air up to three meters. It prefers the upper threshold of the forest and is rarely found on the ground.

Both sides of the anus have scent glands that are used by olingos to mark territory. The function of scent marks may be to attract members of the opposite sex or to mark the boundaries of their territory. Tactile communication is important in competitive relationships, between males and females, and between mothers and their young offspring.

Usually olingo occurs singly, but sometimes there are quite a few large groups(up to six individuals) feeding together.

The mating system is indiscriminate; they do not create pairs for a long time and mate with various individuals. These animals can apparently give birth once a year, with no specific breeding season. There is no specific timing of the mating season to any season.

Puberty occurs at approximately 21-24 months. Olingo pregnancy lasts 73-74 days. Females give birth to one baby at a time. Young cubs are born naked, without hair, with their eyes closed. Newborns weigh about 55 grams. The eyes open on the 27th day. Lactation duration is up to two months. All care for the offspring lies entirely with the female - she provides them with milk, care and protection.

Olingo Allen

Allen's Olingo

(Bassaricyon alleni)

Distributed in South America: Peru, Bolivia, Ecuador, east of the Andes, and possibly Venezuela. Currently, the range of Allen's olingo is very broken and fragmented. Inhabits evergreen forests and primary tropical forests located near open sources of water (rivers and lakes).

Body length is about 40 cm. Adults weigh about 1.23 kg.

Leads a solitary lifestyle, spending a lot of time in trees. By type of nutrition, the olingo is omnivorous. There is no data on reproduction in nature. The breeding season is not expressed. The female gives birth to about 10 babies.

Olingo Beddard

Beddard's Olingo

(Bassaricyon beddardi)

Distributed in Central and northwestern South America. Found in Brazil, Colombia, Costa Rica, Ecuador, Honduras, Nicaragua, Panama, Peru, Uruguay, Guyana and Venezuela. The main population is concentrated in Guyana, with only a small portion in other countries.

Body length - up to 40 cm, tail - 40-48 cm. Weight about 1 kg.

It lives in tropical forests, rising into the mountains to an altitude of 2000 m above sea level. This is a solitary animal that is arboreal and nocturnal. The majority of the Beddard's olingo's diet consists of fruits, nectar, insects, small mammals and birds.

Reproduction occurs throughout the year. Usually the female gives birth to only one calf, which weighs about 55 grams at birth. The eyes open on the 27th day. Lactation lasts up to two months.

Western lowland olingo

Western Lowland Olingo

(Bassaricyon medius)

It lives in the tropical forests of southern Central and northwestern South America from Central Panama to Colombia and Ecuador, where it is distributed west of the Andes. It is found up to an altitude of 1800 m above sea level.

The total length of the body including the tail is from 68 to 90 cm. The tail is equal to the length of the body from the nose to the base of the tail or exceeds this length up to 1.4 times. Body weight from 0.9 to 1.2 kg. The closest species is Allen's olingo, from which it differs in being longer and narrow muzzle, lighter fur due to the lighter ends of the hairs.

Olinguito

Olinguito

(Bassaricyon neblina)

It lives in South America in the moist montane cloud forests of Ecuador and Western Colombia, growing on the slopes of the western and central parts of the Northern Andes. It stays at an altitude of 1500 to 2750 m above sea level.

The smallest species in the raccoon family. Dimensions vary from 32 to 40 cm, tail length - from 33 to 40 cm. Weight is 0.75-1.1 kg. Olingo differs from others in its smaller size, as well as longer, thicker and more colorful hair. In Ecuador it is light brown with black spots, in Colombia it is reddish brown.

Little is known about olinguito. Although the animal is a carnivorous mammal, it feeds mainly on fruits and tree leaves. Leads a nocturnal, solitary lifestyle, lives in the crowns of trees, and rarely descends to the ground. The female of this species has only one cub in the litter.

Cephalopods- the most highly organized invertebrate animals. This class includes squids, cuttlefish, octopuses and nautiluses. These animals usually have a well-separated head, and the leg is transformed into a perioral crown of limbs (arms, or legs and tentacles) and a funnel - a unique organ for the animal’s reactive movement.

Extinct ancient cephalopods had a very peculiar shell with septal partitions. The shape of the shell in ancestral forms was extremely diverse, from straight or curved to varying degrees to twisted in one or more planes. A siphon passed through all the chambers - a tube into which the dorsal outgrowth of the mantle entered, and the chambers (if they were developed) were filled with liquid and gas. Of the modern forms, phragmocone has been preserved only by the nautilus, the small deep-sea cuttlefish spirula and ordinary cuttlefish - sepia, but in the latter it is significantly reduced.

Most cephalopods, although not all, have an ink sac that forms as an outgrowth of the rectum. When an animal is irritated or in a moment of danger, ink is thrown out through the anus in the form of a kind of “smoke screen” or an elongated drop, vaguely reminiscent of the mollusk itself.

The lifespan of most cephalopods is from six months to two years, most often about a year. All cephalopods, without exception, are dioecious. In males of many species, one of the arms is used to transfer spermatophores to the female. Usually only part of the male’s arm is transformed, but in pelagic argonaut octopuses, the male of which is much smaller than the female (only about 5% of its length), his 3rd left arm, counting from the dorsal side, develops entirely into a huge one in relation to the size of the dwarf male the hectocotylus, which, after being charged with sperm (the Argonaut has no spermatophores), breaks off, independently crawls along the female’s body, crawls into her mantle cavity and is stored there.

Cephalopods (except Nautilus and Argonaut) reproduce once in their lives, after which they die immediately or after some time. In some oceanic squids and cuttlefish, spawning is very extended, while in deep-sea bottom-finned octopuses, the nautilus and the argonaut, it is intermittent. Nevertheless, they should be considered monoparous animals.

No monogamous species are known among cephalopods. Almost random mating is typical for males. Females, in addition, “practice” the so-called “simultaneous polyandry”. A female Pacific bottom octopus was observed to mate with 6 males at once within 24 hours.

It is very typical for cephalopods to have chromatophores in their skin - complex sacs with colored pigment that allow the animal to change color very quickly, in a second.

A number of cephalopods have luminescent organs - photophores, which can be located both on the outer surface of the body and on internal organs.

Some cephalopods have blue blood because... Instead of hemoglobin, which contains iron, it contains hemocyanin, which contains copper.

But perhaps the most important evolutionary “acquisition” of cephalopods is the brain, which has a rudimentary cortex. In more primitive external shell forms (nautilus), the central nervous system consists of scattered ganglia lying on a cartilaginous plate, and the brain has 13 lobes. In highly developed intrashell forms (squids, cuttlefish, octopuses), the central nervous system is highly integrated. Their brain is well isolated, completely enclosed in a cartilaginous shell and has 2-3 times more lobes than that of the nautilus. The brain has association zones, similar to the vertebrate cerebral cortex, as a result of which higher cephalopods are capable of learning.

Cephalopods are also distinguished by well-developed organs of vision, which in terms of complexity of structure and functions are sometimes not inferior to the eyes of higher vertebrates, including humans. In the giant squid Architeuthis, the diameter of the eyeball can reach 40 cm (and possibly more)! More than half of the brain's nervous tissue is located in the optic lobes.

The extreme size of cephalopods is astonishing: the miniature cuttlefish Idiosepius is only about 10 mm long, while Architeuthis can be up to 18 m in total length (and possibly more) and weigh up to a ton - the largest of modern invertebrates

Until the end of the Cambrian, there were few cephalopods, but in the Ordovician the group began a “golden age”, and they spread throughout the world. Despite the fact that the ancestor of cephalopods was no more than 2 cm in size, already in the Middle Ordovician real giant endocerids appeared with a shell length of more than 10 m! Among the ammonites, already at the end of their history in Cretaceous period, there were also giants with a curled shell diameter of 3.5 m (the size of an elephant)! The weight of such monsters was apparently several tons.

The history of the class of cephalopods has been going on for more than 500 million years, during which numerous ups and downs in the diversity of species and life forms have occurred regularly, with periods ranging from 7 to 300 million years. The entire history of the group was built, so to speak, on attempts to find a morpho-ecological solution to the problem of adaptation to pelagic existence. To maintain buoyancy, ancient cephalopods “chose” two main methods. One way is to preserve the outer shell and achieve hydrostatic equilibrium by changing the pressure in the chambers of the phragmocone. Another method is the reduction of the shell, up to its complete loss, and an active lifestyle while maintaining negative buoyancy. Some modern forms have developed a third way - achieving neutral buoyancy after complete loss of the shell due to watering the tissues and compensating for the weight of “heavy” parts of the body with “floats” filled with light (lighter than water) liquid.

The first path turned out to be an evolutionary dead end for most groups, and of the huge number of species with an external shell, only nautiloids survived - forms with the most simply constructed shell. Thus, there are approximately 20 times more extinct species of cephalopods than modern ones.

The second path turned out to be more successful and led to the emergence of modern forms, in which the shell was overgrown with a mantle on all sides and turned into an internal axial skeleton (an analogue of the notochord and spine) or disappeared altogether. During the evolution of the class, the ecological structure of life forms changed, and in different eras there was a different ratio of planktonic, nektonic, benthic and benthopelagic species.

Modern cephalopods are represented by two large taxonomic groups (subclasses): nautiloids (there is an external shell; 2 genera and several species of a single family of nautilids) and coleoids (the shell is hidden under the mantle, partially or completely reduced; about 700 species, 140 genera, 45 families, 4 squads).

Nautilus- The animal is remarkable in many ways. Firstly, this is a real “living fossil”, which, like the lobe-finned fish Coelacanth, has been preserved, practically unchanged, for tens of millions of years. Secondly, it retained a number of primitive structural features and way of life. And finally, and this is perhaps the most important thing, it was precisely thanks to the presence of a true phragmocone that the nautilus turned out to be a kind of “connecting link” between modern internal-shelled cephalopods and many extinct external-shelled animals, such as ammonites.

To subclass coleoid include the orders of squids, cuttlefish and octopuses. Squids and cuttlefish are sometimes combined into the superorder decapods - they all have 4 pairs of arms and, as a rule, 1 pair of hunting tentacles between the 3rd and 4th pairs of arms. In addition to those listed, there is also a fourth detachment, with a single representative whose name, translated from Latin, sounds ominous: “hellish vampire squid.” In fact, this is a small, up to 40 cm, quite peaceful pelagic deep-sea (usually lives at depths of more than 3 km) relict species, combining the characteristics of finned octopuses and decapods.

To the squad cuttlefish include two large groups of cephalopods: the cuttlefish proper, or sepiids, and the so-called bobtails (from the English bobtail squid - short-tailed squid), or sepiolids. In addition, the order of cuttlefish includes the amazing cephalopod Spirula as an independent suborder. This small mollusk, no more than 5 cm long, differs from all others in that its shell is divided into chambers by partitions - a real phragmocone of ancient cephalopods! Only, unlike the nautilus and ammonites, this shell is not external, but hidden in the thickness of the mantle and twisted not on the dorsal, but on the ventral side

Spirula lives in the tropics, and is absent from our waters. In the south of Primorye there is one species of true cuttlefish, the Japanese cuttlefish, and two species of sepiolids: Pacific Russia and two-horned sepiola. The fins of the cuttlefish border the mantle with a narrow ribbon; eyes of the so-called myopside type (the anterior chamber of the eye communicates with the environment only through a small hole in the cornea). The cuttlefish lives at the bottom in coastal zone and can cleverly disguise itself as the color of the soil, lying in wait for prey - fish and crustaceans.

Unlike true cuttlefish, which live mainly on the shelf and only occasionally descend to depths of more than 200 m, sepiolids sometimes found deeper than 1 km. Sepiolids are quite small animals: the greatest length of the mantle of Pacific Russia, the largest of the sepiolids, reaches 10 cm with a weight of 250 g, but is usually much less. For comparison: the largest true cuttlefish from the tropics of Southeast Asia reaches a length of 50 cm and a weight of 12 kg! Genetic studies have also shown that sepiolids are a well-distinct group. Apparently, they can be considered an independent order of the class of cephalopods.

True cuttlefish are characterized by complex mating behavior. Competition between males for the right to pass on their genes to the next generation can be quite original. So, often before mating, a male literally scratches out with the tips of his hands and uses a funnel to blow out from the female’s seminal receptacle the sperm of another male that has preceded him, and only then begins to mate! Large cuttlefish have special “leks” where the male demonstrates his masculine beauty and power to the female. The eggs of cuttlefish and sepiolids are large, usually up to 1 cm, less often up to 2 cm in diameter; in sepiolids they are covered with a hard calcareous shell and are laid in groups on underwater objects. Embryonic development in heat-loving species is short, 1-2 months, while in cold-water Pacific Russia the incubation duration can reach up to 9 months. Cuttlefish have no care for their offspring, and the animals die a short time after spawning.

Squid- the most numerous order of cephalopods. In squids, the calcareous part of the shell is completely reduced, and only a chitinous translucent plate, or gladius, remains of the shell. Just under 30 families of squid are grouped into two suborders: myopsids (2 families in total and about 50 species) and egopsids (23-25 ​​families and more than 200 species).

Squids, like cuttlefish, with rare exceptions, do not care for their offspring.

Another thing - octopuses. For many representatives of this order, caring for offspring takes up a considerable part of their lives and sometimes takes bizarre forms. The females of some octopuses that live on the sandy bottom carry clutches with them in their arms. Thus, the female of one small Atlantic tropical coastal species was met with a huge clutch of 36 thousand eggs, which weighed almost half the body weight of the octopus itself! The Argonaut female lays fertilized eggs in a thin calcareous shell, in which she lives and which she forms with the secretions of the first pair of hands. Some pelagic octopuses have become truly viviparous: their eggs, after fertilization, remain in long curved oviducts, embryonic development occurs as the eggs move along the oviducts, and young octopuses emerge. All this variety of parental care has evolved and is characteristic of ordinary octopuses.

In general, the order of octopuses is divided into two well-separated suborders: finned and ordinary octopuses. The first suborder includes deep-sea octopuses with a gelatinous body, two fins on the sides of the body and two rows of antennae along the inner surface of each arm on each side of a single row of suckers. They live at depths usually greater than 500 m.

The suborder of common octopuses is much more diverse and rich in species. They do not have fins, barbels on their arms, or the cartilaginous vestige of a shell. Although there are many pelagic species among these octopuses, most live on the bottom. Bottom-dwelling species can swim or move along the bottom using their arms, literally walking. True octopuses have almost completely lost their shells. That is why they are extremely plastic and can literally seep through narrow cracks in rocks. All octopuses, unlike decapods, do not have chitinous rings in their suckers and, therefore, do not have hooks. There are up to 200 species of true octopuses, about half of them belong to the same genus Octopus. The combination of so many species into one genus is artificial, does not reflect family ties and is caused only by the great morphological similarity of these octopuses. The artificiality of the Octopus genus has been convincingly proven by molecular genetic studies.

The Far Eastern seas of Russia are home to the giant octopus, the largest of all KNOWN octopus species. Individual specimens of this species grow up to 5 m (according to some sources, even up to 10 m!) in length and weigh up to 60, presumably even up to 180 kg or more! On the Primorye shelf, mature male giant octopuses weigh 8-25 kg or more, usually 10-15 kg; The average weight of mature females is 11-21 kg. Giant octopuses grow very quickly, gaining up to 2% of their body weight daily, and live, according to various estimates, 3-5 years. There are three known subspecies of the giant octopus. The smallest lives in the Bering Sea and the Kuril Islands, where mature individuals usually have no more than 1 m in length and weigh up to 4 kg. In Primorye and off the western coast of North America, larger subspecies live, which are genetically practically indistinguishable, but differ well from the Bering Sea. The giant octopus is a very intelligent and beautiful animal and is often kept in aquariums. This is a completely peaceful creature, although there are reliably known facts of unprovoked attacks by an octopus on people at sea. Interestingly, the larger the octopus, the less aggressive it is. The exception is males during the breeding season.

Octopuses are solitary animals and spend almost all their time in shelters (juveniles in mollusk shells, adults in rock burrows and caves). Octopuses are quite skilled in hunting techniques. They can ambush actively swimming fish, collect shellfish by rummaging under stones, and can catch fish with a “cast net”, which is obtained by inflating the membrane between their hands. At the Seattle Aquarium, a large giant octopus managed to catch a 1 m long dogfish, a 0.6 m long stingray and a 1.5 kg chinook salmon using the tip of its outstretched arm as fish bait! Octopuses also eat stingray embryos, removing them from hard-shelled egg capsules using their beak and radula. With its radula, the octopus can drill through large shells of mollusks, which it cannot open with the help of suction cups.

Unlike decapods, octopuses do not have a courtship phase before mating. Mating in a giant octopus is long: the male holds the female in his arms for 2 to 4 hours. In other species, there may be no "full contact" between the sexes, and the male transfers spermatophores to the female at the tip of his hectocotylated hand. After mating, the male does not die immediately and can live for several more months. He practically does not eat, becomes very active and quickly loses weight, and by the end of his life his skin begins to “decrepit” and hang in tatters.

The female giant octopus lays up to 50 thousand small, 6-8 mm long eggs on the ceiling and walls of the underwater lair and begins to protect and carefully care for the clutch. She constantly sits in the den, blows a stream of fresh water through the eggs through a funnel, cleans them with suction cups, and removes sick and dead eggs. The duration of such “incubation” depends on the water temperature, and the hatching of young octopuses begins 5-8 months after laying the eggs, and maybe more. The female waits patiently until the last of her cubs hatches, and after some time, usually within a month, she dies. During the “incubation” of the clutch, the female loses 50-93% of her weight! Octopuses crawl out of the egg, mantle first, with remains yolk sac, which usually falls off or is resorbed within 24 hours. Newborns weigh about 20-30 mg. The juveniles actively swim and feed in the water column, and only after a few months begin to settle to the bottom. By this time, the arms and mantle of young octopuses lengthen, and the eyes move from the sides to the dorsal side. Having settled to the bottom, octopuses immediately look for shelter; usually, they first take refuge in the thickness of gravel, and later occupy empty mollusk shells, begin to move along the bottom on their hands and hunt like adults.

Large octopuses are dangerous, and the main danger is not the strong tentacles of large octopuses, but their poisonous saliva, which has a paralyzing effect on prey. Signs of the disease resemble those of a snake bite. Off the coast of Australia and Japan live small spotted blue octopuses, whose bite can even be fatal to humans.

Of the marine invertebrate animals, the most gifted are cephalopods: squid, cuttlefish and octopuses. The development in animals of organs capable of using the simplest tools leads to the formation of a more complex brain, to the expansion of the scope of its activity, to the formation of various adaptive reflexes. Octopuses are the smartest of all invertebrates. They are trainable, have a good memory, and recognize geometric shapes. They recognize people and get used to those who feed them.

Cephalopods are the only deep-sea invertebrates that have good visual memory, and they use it better than any other vertebrate. Their eyes, which have more than 70 million visual cells, surpass human eyes in visual acuity. They allow the animal to distinguish colors, and can adapt to different distances by changing focus. Moreover, cephalopods can determine the condition of the seabed by feeling it with their tentacles - this information is very important when choosing camouflage.

You can find one octopus, skillfully camouflaged to match the sand on which it lies, and a few meters away from it, a second one, taking on the colors of the rough, dark fragment of the reef on which it is located. For such an absolute adaptation of appearance to the environment, the octopus needs two sources of information: data about color that the eyes give him, and data about texture or surface structure that the organs of touch provide him. When they hunt fish, they also respond to each action of the prey by changing color, becoming lighter or darker. The darker color serves as an indicator of aggression.

The cuttlefish, if it is frightened, reacts in a completely special way: it becomes pale, but remains two very dark spots on the back, apparently designed to convince the intended enemy that these are the eyes of a much larger animal buried in the sand.

Cephalopods are highly capable of learning. Laboratory tests have shown that they can use tools and learn from experience - abilities that have so far only been discovered in great apes.

A glass hollow cylinder, open at the top, was placed in an aquarium with an octopus. In the cylinder is a crab, the octopus's favorite food. The mollusk soon saw the crab, the cylinder stood one and a half meters away from it. An attack followed, but the glass delayed the octopus at the very target.

The octopus wriggled in vain attempts to grab such desired and close prey. In rage he flared up with one or another shade of crimson. It is unknown how long he would have continued his fruitless attempts, but one tentacle inadvertently jumped over the upper edge of the cylinder and its tip penetrated into the vessel with the crab. Immediately the octopus changed tactics: apparently, the tip of the tentacle smelled the crab, and the blind man led the sighted one. The tentacle, bending over the edge of the cylinder, stretched further and further, inexorably approaching the crab, and the octopus crawled behind it, climbing up the glass. Finally, the tentacle touched the crab and the next second the octopus jumped over the glass wall and grappled with the crab.

Now the octopus knew exactly how to get the crab from behind the glass. But he did not go straight to the crab through the top, but first rushed at the crab, as before, trying to grab it through the glass, only then crawled upward with tentacles that seemed to know the way better. In other words, he exactly repeated his first attempt, which was crowned with success.

The cuttlefish was also asked to remove a shrimp from a jar without a lid. For thirty hours in a row (according to other sources, adult cuttlefish stop their fruitless attempts after an hour), the cuttlefish fought against the glass, attacking head-on, but never thought to rise up a little, as the octopus did.

A few days later the experiment was complicated. The cylinder with the crab was covered with glass. But the tentacles, having studied the road well, bypassed this obstacle without much difficulty. After several unsuccessful attempts they felt a microscopic gap between the flat roof and the side of the can. They lifted the lid and led the octopus behind them.

We took a break of seven days and then repeated the experiment again. The octopus still found the correct solution to the problem. The conditioned reflex, even not reinforced by an additional lesson, continued to operate flawlessly. The cuttlefish, having learned to get food from behind the glass, after eighteen hours forgot how to remove a tasty morsel from the jug without breaking the walls with its forehead).

Octopuses walk on tentacles along the bottom, carry weights in them, build nests from stones, open mollusk shells, attach eggs to stones, and when the octopus sleeps, some tentacles serve as guards. In accordance with the versatile purpose, the roles are distributed between the different tentacles. The tentacles of the second pair from the top, which are usually the longest, are used by octopuses as attack weapons. When attacking prey and defending against an enemy, octopuses try to grab the enemy with these tentacles. In peacetime, fighting arms turn into legs: they serve as stilts when moving along the bottom. The uppermost pair of hands is intended for examining and feeling surrounding objects, and the two lower tentacles are on guard during sleep.

In deep sleep, all the octopus' tentacles, except the two lower ones, are pressed to the body, and the guard arms are extended to the sides. From time to time they stretch upward and slowly circle above the sleeping octopus, like a radar antenna. The octopus is in deep sleep. He doesn't see or hear anything. But as soon as you lightly shake the water or slightly touch the guard tentacles (namely these, and not others!), the animal immediately jumps up.

Cephalopods are a potential human food reserve. About 75 are known commercial species cephalopods, 64 of which live in the coastal zone (cuttlefish, neritic loliginid squids and benthic octopuses). The annual catch of cephalopods in marine commercial catches has approached 3 million tons. The main consumers of cephalopods are Japan and the countries of Southeast Asia.

IN lately“gastronomic” human interest in cephalopods has increased sharply, since their meat is a complete protein food that can replace fish. Squid can be found in the sea in schools of thousands and are easy to catch with nets. Octopuses are caught individually - with spears or with the help of “jug traps”, which the octopuses take for shelter and willingly occupy. In Japan, Korea and China, instead of traps, ordinary clay jars are often used, only with a hole in the bottom, to drive out the caught octopus.

Besides humans, cephalopods have many enemies. Moray eels, conger eels and stingrays lurk between the reefs. In the open sea, cephalopods become prey for sharks and catfish whales, and in shallow waters they are threatened by birds and seals. This strict natural selection means that only animals with a high level of development of behavioral stereotypes survive.

In some countries, paint and ink are made from the ink liquid of cephalopods.

Class Cephalopoda

Cephalopods are the most highly organized mollusks. They are rightly called the “primates” of the sea among invertebrate animals for the perfection of their adaptations to life in the marine environment and the complexity of their behavior. These are mainly large predatory marine animals capable of actively swimming in the water column. These include squids, octopuses, cuttlefish, and nautiluses (Fig. 234). Their body consists of a torso and a head, and the leg is transformed into tentacles located on the head around the mouth, and a special motor funnel on the ventral side of the body (Fig. 234, A). This is where the name comes from - cephalopods. It has been proven that some of the tentacles of cephalopods are formed due to the cephalic appendages.

Most modern cephalopods have no or vestigial shells. Only the genus Nautilus has a spirally twisted shell, divided into chambers (Fig. 235).

Modern cephalopods include only 650 species, while fossil species number about 11 thousand. This is an ancient group of mollusks known since the Cambrian. Extinct species of cephalopods were predominantly testate and had an external or internal shell (Fig. 236).

Cephalopods are characterized by many progressive organizational features due to the active lifestyle of marine predators. At the same time, they retain some primitive characteristics that indicate their ancient origin.

External structure. Peculiarities external structure Cephalopods are diverse due to different lifestyles. Their sizes range from a few centimeters to 18 m in some squids. Nektonic cephalopods are usually torpedo-shaped (most squids), benthic ones have a sac-shaped body (many octopuses), and nektobenthic ones are flattened (cuttlefish). Planktonic species are small in size and have a gelatinous buoyant body. The body shape of planktonic cephalopods can be narrow or jellyfish-like, and sometimes spherical (squid, octopus). Benthopelagic cephalopods have a shell divided into chambers.

The body of cephalopods consists of a head and a trunk. The leg is modified into tentacles and a funnel. On the head there is a mouth surrounded by tentacles and large eyes. The tentacles are formed by the head appendages and the leg. These are food capture organs. The primitive cephalopod (Nautilus) has an indefinite number of tentacles (about 90); they are smooth, worm-shaped. In higher cephalopods, the tentacles are long, with powerful muscles and bear large suckers on the inner surface. The number of tentacles is 8-10. Cephalopods with 10 tentacles have two tentacles - hunting ones, longer, with suckers at the extended ends,

Rice. 234. Cephalopods: A - nautilus Nautilus, B - octopus Benthoctopus; 1 - tentacles, 2 - funnel, 3 - hood, 4 - eye

Rice. 235. Nautilus Nautilus pompilius with a sawn shell (according to Owen): 1 - head hood, 2 - tentacles, 3 - funnel, 4 - eye, 5 - mantle, 6 - internal sac, 7 - chambers, 8 - partition between shell chambers, 9 - siphon

Rice. 236. Scheme of the structure of cephalopod shells in a sagittal section (from Gescheler): A - Sepia, B - Belosepia, C - Belemnites, D - Spirulirostra, E - Spirula, F - Ostracoteuthis, G - Ommastrephes, H - Loligopsis (C, D, E - fossils); 1 - proostracum, 2 - dorsal edge of the siphonal tube, 3 - ventral edge of the siphonal tube, 4 - set of phragmocone chambers, 5 - rostrum, 6 - siphon cavity

and the remaining eight tentacles are shorter (squid, cuttlefish). Octopuses that live on the seabed have eight tentacles of equal length. They serve the octopus not only to capture food, but also to move along the bottom. In male octopuses, one tentacle is modified into a sexual one (hectocotyl) and serves to transfer reproductive products into the mantle cavity of the female.

The funnel is a derivative of the leg in cephalopods and serves for a “reactive” method of movement. Through the funnel, water is forcefully pushed out of the mantle cavity of the mollusk, and its body moves reactively in opposite direction. In the boat, the funnel is not fused on the ventral side and resembles the sole of the foot of crawling mollusks rolled into a tube. Evidence that the tentacles and funnel of cephalopods are derived legs is their innervation from the pedal ganglia and the embryonic anlage of these organs on the ventral side of the embryo. But, as already noted, some of the tentacles of cephalopods are derivatives of the cephalic appendages.

The mantle on the ventral side forms a kind of pocket - a mantle cavity that opens outwards with a transverse slit (Fig. 237). A funnel protrudes from this gap. On the inner surface of the mantle there are cartilaginous protrusions - cufflinks, which fit tightly into the cartilaginous grooves on the body of the mollusk, and the mantle is, as it were, fastened to the body.

The mantle cavity and the funnel together provide jet propulsion. When the muscles of the mantle relax, water enters through the gap into the mantle cavity, and when it contracts, the cavity is closed with cufflinks and the water is pushed out through the funnel. The funnel can bend to the right, left and even back, which provides different direction movements. The role of the steering wheel is additionally performed by the tentacles and fins - skin folds of the body. The types of movement in cephalopods are varied. Octopuses often move on tentacles and swim less often. In cuttlefish, in addition to the funnel, a circular fin serves for movement. Some umbrella-shaped deep-sea octopuses have a membrane between the tentacles - the umbrella and can move due to its contractions, like jellyfish.

The shell of modern cephalopods is vestigial or absent. The ancient extinct cephalopods had a well-developed shell. Only one modern genus, Nautilus, has retained a developed shell. The shell of Nautilus, even in fossil forms, has significant morphofunctional features, in contrast to the shells of other mollusks. This is not only a protective device, but also a hydrostatic device. The nautilus has a spirally twisted shell divided into chambers by partitions. The body of the mollusk is placed only in the last chamber, which opens with its mouth outward. The remaining chambers are filled with gas and chamber liquid, which ensures the buoyancy of the mollusk’s body. Through

The siphon, the posterior process of the body, passes through the holes in the partitions between the chambers of the shell. Siphon cells are capable of releasing gases. When floating, the mollusk releases gases, displacing the chamber liquid from the chambers; when sinking to the bottom, the mollusk fills the chambers of the shell with chamber liquid. The propeller of the nautilus is a funnel, and the shell keeps its body suspended in the water. Fossil nautilids had a shell similar to that of the modern nautilus. The completely extinct cephalopods - ammonites also had an external, spirally twisted shell with chambers, but their partitions between the chambers had a wavy structure, which increased the strength of the shell. That is why ammonites could reach very large sizes, up to 2 m in diameter. Another group of extinct cephalopods, the belemnites (Belemnoidea), had an internal shell, overgrown with skin. Belemnites by appearance resembled shellless squids, but in their body there was a conical shell divided into chambers. The top of the shell ended with a point - the rostrum. Belemnite shell rostrums are often found in Cretaceous deposits and are called "devil's fingers". Some modern shellless cephalopods have rudiments of an internal shell. Thus, on the cuttlefish’s back, under the skin, a calcareous plate is preserved, which has a chamber structure when cut (238, B). Only the Spirula has a fully developed spirally twisted shell under its skin (Fig. 238, A), and the squid has only a horny plate under its skin. Females of modern cephalopods, Argonauta, have a developed brood chamber resembling a spiral shell in shape. But this is only a superficial resemblance. The brood chamber is secreted by the epithelium of the tentacles, is very thin and is designed to protect the developing eggs.

Veils. The skin is composed of single-layer epithelium and a layer connective tissue. The skin contains pigment cells - chromatophores. Cephalopods are characterized by the ability to quickly change color. This mechanism is controlled by the nervous system and is carried out by changing the shape

Rice. 238. Shell rudiments in cephalopods (according to Natalie and Dogel): A - spirula; 1 - funnel, 2 - mantle cavity, 3 - anus, 4 - excretory opening, 5 - luminescent organ, 6 - fin, 7 - shell, 8 - siphon; B - Sepia shell; 1 - septa, 2 - lateral edge, 3 - siphonal fossa, 4 - rostrum, 5 - siphon rudiment, 6 - posterior edge of the proostracum

pigment cells. So, for example, a cuttlefish, swimming over sandy soil, takes on a light color, and over rocky soil - dark. .At the same time, in her skin, pigment cells with dark and light pigment alternately shrink and expand. If you cut the optic nerves of a mollusk, it loses the ability to change color. Due to the connective tissue of the skin, cartilage is formed: in cufflinks, the bases of the tentacles, around the brain.

Protective devices. Cephalopods, having lost their shell during the process of evolution, acquired other protective devices. Firstly, fast movement saves many of them from predators. In addition, they can defend themselves with tentacles and a “beak”, which is modified jaws. Large squids and octopuses can fight with large marine animals, such as sperm whales. Sedentary and small forms have developed protective coloration and the ability to quickly change color. Finally, some cephalopods, such as cuttlefish, have an ink sac, the duct of which opens into the hindgut. Spraying the ink liquid into the water creates a kind of smoke screen, allowing the mollusk to hide from predators to a safe place. Cuttlefish ink gland pigment is used to make high-quality artist's ink.

Internal structure of cephalopods

Digestive system cephalopods bear the features of specialization in feeding on animal food (Fig. 239). Their food consists mainly of fish, crabs and bivalves. They grab prey with their tentacles and kill them with their jaws and poison. Despite their large size, cephalopods can only feed on liquid food, since they have a very narrow esophagus, which passes through the brain, enclosed in a cartilaginous capsule. Cephalopods have devices for grinding food. To chew prey, they use hard horny jaws, similar to the beak of a parrot. In the pharynx, food is ground by the radula and abundantly moistened with saliva. The ducts of 1-2 pairs of salivary glands flow into the pharynx, which secrete enzymes that break down proteins and polysaccharides. The second posterior pair of salivary glands secretes poison. Liquid food from the pharynx passes through the narrow esophagus into the endodermal stomach, into which the ducts of the paired liver flow, which produces a variety of digestive enzymes. The hepatic ducts are lined with small accessory glands, the totality of which is called the pancreas. The enzymes of this gland act on polysaccharides,

and therefore this gland is functionally different from the mammalian pancreas. The stomach of cephalopods usually has a blind sac-like process, which increases its volume, which allows them to absorb a large portion of food. Like other carnivorous animals, they eat a lot and relatively rarely. The small midgut departs from the stomach, which then passes into the posterior intestine, which opens through the anus into the mantle cavity. The duct of the ink gland flows into the hindgut of many cephalopods, the secretion of which has a protective significance.

Nervous system Cephalopods are the most highly developed among mollusks. The nerve ganglia form a large peripharyngeal cluster - the brain (Fig. 240), enclosed in a cartilaginous capsule. There are additional ganglia. The brain primarily consists of: a pair of large cerebral ganglia that innervate the head, and a pair of visceral ganglia that send nerve cords to the internal organs. On the sides of the cerebral ganglia there are additional large optic ganglia that innervate the eyes. From the visceral ganglia, long nerves extend to two star-shaped pallial ganglia, which develop in cephalopods in connection with the function of the mantle in their reactive mode of movement. The brain of cephalopods includes, in addition to the cerebral and visceral, pedal ganglia, which are divided into paired ganglia of the tentacles (brachial) and the funnel (infidibular). A primitive nervous system, similar to the scalene system of bokonervna and monoplacophorans, is preserved only in Nautilus. It is represented by nerve cords forming the peripharyngeal ring without ganglia and the pedal arch. Nerve cords are covered with nerve cells. This structure of the nervous system indicates the ancient origin of cephalopods from primitive shell mollusks.

Sense organs cephalopods are well developed. Their eyes, which have highest value for orientation in space and hunting for prey. In Nautilus, the eyes have a simple structure in the form of a deep optic fossa (Fig. 241, A), while in other cephalopods the eyes are complex - in the shape of an optic vesicle and reminiscent of the structure of the eye in mammals. This is an interesting example of convergence between invertebrates and vertebrates. Figure 241, B shows the eye of a cuttlefish. The top of the eyeball is covered with the cornea, which has an opening into the anterior chamber of the eye. The connection of the anterior cavity of the eye with the external environment protects the eyes of cephalopods from action high pressure at great depths. The iris forms an opening - the pupil. Light through the pupil hits the spherical lens formed by the epithelial body - the upper layer of the eye bladder. Accommodation of the eye in cephalopods occurs differently,

Rice. 240. Nervous system of cephalopods: 1 - brain, 2 - optic ganglia, 3 - pallial ganglia, 4 - intestinal ganglion, 5 - nerve cords in the tentacles

than in mammals: not by changing the curvature of the lens, but by bringing it closer to or moving away from the retina (similar to focusing a camera). Special ciliary muscles come to the lens, causing it to move. The cavity of the eyeball is filled with a vitreous body that has a light-refracting function. The bottom of the eye is lined with visual - retinal and pigment - cells. This is the retina of the eye. A short optic nerve departs from it to the optic ganglion. The eyes, together with the optic ganglia, are surrounded by a cartilaginous capsule. Deep-sea cephalopods have luminous organs on their bodies, built like eyes.

Organs of balance- statocysts are located in the cartilaginous capsule of the brain. The olfactory organs are represented by olfactory pits under the eyes or osphradia typical of mollusks at the base of the gills - in the nautilus. The taste organs are concentrated on the inner side of the ends of the tentacles. Octopuses, for example, use their tentacles to distinguish edible objects from inedible ones. The skin of cephalopods contains many tactile and light-sensitive cells. In search of prey, they are guided by a combination of visual, tactile and gustatory sensations.

Respiratory organs represented by ctenidia. Most modern cephalopods have two, but Nautilus has four. They are located in the mantle cavity on the sides of the body. The flow of water in the mantle cavity, which ensures gas exchange, is determined by the rhythmic contraction of the muscles of the mantle and the function of the funnel through which water is pushed out. During the reactive mode of movement, the flow of water in the mantle cavity accelerates, and the intensity of respiration increases.

Circulatory system cephalopods are almost closed (Fig. 242). Due to active movement, their coelom and blood vessels are well developed and, accordingly, parenchymality is poorly expressed. Unlike other mollusks, they do not suffer from hypokenia - weak mobility. Their blood flow rate is ensured by their work well developed heart, consisting of a ventricle and two (or four - in Nautilus) atria, as well as pulsating sections of blood vessels. The heart is surrounded by a large pericardial cavity,

which performs many of the functions of the coelom. The cephalic aorta extends forward from the ventricle of the heart and the splanchnic aorta extends backward. The cephalic aorta branches into arteries that supply blood to the head and tentacles. Vessels extend from the splanchnic aorta to the internal organs. Blood from the head and internal organs is collected in the vena cava, located longitudinally in the lower part of the body. The vena cava is divided into two (or four in Nautilus) afferent gill vessels, which form contractile extensions - gill “hearts”, facilitating gill circulation. The afferent gill vessels lie close to the kidneys, forming small blind invaginations into the kidney tissue, which helps to free venous blood from metabolic products. In the gill capillaries, blood is oxidized, which then enters the efferent gill vessels, which flow into the atria. Some of the blood from the capillaries of veins and arteries flows into small lacunae, and therefore circulatory system Cephalopods should be considered almost closed. The blood of cephalopods contains a respiratory pigment - hemocyanin, which includes copper, so when oxidized, the blood turns blue.

Excretory system represented by two or four (in Nautilus) kidneys. With their inner ends they open into the pericardial sac (pericardium), and with their outer ends into the mantle cavity. Excretion products enter the kidneys from the branchial veins and from the extensive pericardial cavity. Additionally, the excretory function is performed by the pericardial glands formed by the wall of the pericardium.

Reproductive system, reproduction and development. Cephalopods are dioecious animals. In some species, sexual dimorphism is well expressed, for example in the argonaut (Argonauta). The female Argonaut is larger than the male (Fig. 243) and during the breeding season, with the help of special glands on the tentacles, she secretes around her body a thin-walled parchment-like brood chamber for gestating eggs, similar to a spiral shell. The male Argonaut is several times smaller than the female and has a special elongated sexual tentacle, which is filled with reproductive products during the breeding season.

Gonads and reproductive ducts are unpaired. The exception is the nautilus, which has preserved paired ducts extending from the unpaired gonad. In males, the vas deferens passes into the spermatophore sac, where spermatozoa are glued together into special packages - spermatophores. In cuttlefish, the spermatophore is checker-shaped; its cavity is filled with sperm, and the outlet is closed with a complex plug. During the breeding season, the male cuttlefish uses a genital tentacle with a spoon-shaped end to transfer the spermatophore into the mantle cavity of the female.

Cephalopods usually lay eggs at the bottom. Some species exhibit care for their offspring. Thus, the female Argonaut bears eggs in the brood chamber, and octopuses guard the clutch of eggs, which are placed in shelters made of stones or in caves. Development is direct, without metamorphosis. The eggs hatch into small, fully formed cephalopods.

Modern cephalopods belong to two subclasses: the subclass Nautiloidea and the subclass Coleoidea. The extinct subclasses include: subclass Ammonoidea, subclass Bactritoidea and subclass Belemnoidea.

Subclass Nautilidae

Modern nautilids include one order Nautilida. It is represented by only one genus, Nautilus, which includes only a few species. The distribution range of Nautilus is limited to the tropical regions of the Indian and Pacific Oceans. There are more than 2,500 species of nautilid fossils. This is an ancient group of cephalopods, known since the Cambrian.

Nautilids have many primitive features: the presence of an external multi-chambered shell, an unfused funnel, numerous tentacles without suckers, and the manifestation of metamerism (four ctenidia, four kidneys, four atria). The similarity of nautilids with lower shell mollusks is manifested in the structure of the nervous system from cords without separate ganglia, as well as in the structure of coelomoducts.

Nautilus is a benthopelagic cephalopod. It floats in the water column in a “reactive” way, pushing water out of the funnel. The multi-chamber shell ensures the buoyancy of its body and sinking to the bottom. The Nautilus has long been an object of fishing for its beautiful mother-of-pearl shell. Many exquisite pieces of jewelry are made from nautilus shells.

Subclass Coleoidea

Coleoidea means "hard" in Latin. These are hard-skinned mollusks without a shell. Coleoids are a thriving group of modern cephalopods, comprising four orders, which include about 650 species.

Common features of the subclass are: lack of a developed shell, fused funnel, tentacles with suction cups.

Unlike nautilids, they have only two ctenidia, two kidneys and two atria. Coleoidea have a highly developed nervous system and sensory organs. The largest number The species are characterized by the following three orders.

Order Cuttlefish (Sepiida). The most characteristic representatives of the order are cuttlefish (Sepia) and Spirula (Spirula) with rudiments of an internal shell. They have 10 tentacles, two of which are hunting tentacles. These are nektobenthic animals, stay near the bottom and are able to actively swim.

Order Squids (Teuthida). This includes many commercial squids: Todarodes, Loligo, etc. Squids sometimes retain a rudiment

shells in the form of a horny plate under the skin on the back. They have 10 tentacles, like the previous squad. These are mainly nektonic animals that actively swim in the water column and have a torpedo-shaped body (Fig. 244).

Order Octopoda (Octopoda). They are an evolutionarily advanced group of cephalopods without traces of a shell. They have eight tentacles. Sexual dimorphism is pronounced. Males develop a sexual tentacle - a hectocotylus. This includes a variety of octopuses (Fig. 245). Most octopuses lead a bottom-dwelling lifestyle. But among them there are nektonic and even planktonic forms. The order Octopoda includes the genus Argonauta - the argonaut, in which the female secretes a special brood chamber.

Practical significance of cephalopods

Cephalopods are game animals. The meat of cuttlefish, squid and octopus is used for food. The world catch of cephalopods currently reaches more than 1,600 thousand tons. per year. Cuttlefish and some octopuses are also harvested for the purpose of obtaining ink liquid, from which natural ink and ink of the highest quality are made.

Paleontology and phylogeny of cephalopods

The most ancient group of cephalopods is considered to be nautilids, whose fossil shells are already known from Cambrian deposits. Primitive nautilids had a low conical shell with only a few chambers and a wide siphon. Cephalopods are thought to have evolved from ancient crawling testate mollusks with simple conical shells and flat soles, like some fossil monoplacophorans. Apparently, a significant aromorphosis in the emergence of cephalopods was the appearance of the first partitions and chambers in the shell, which marked the beginning of the development of their hydrostatic apparatus and determined the ability to float up, breaking away from the bottom. Apparently, the formation of the funnel and tentacles occurred in parallel. The shells of ancient nautilids were varied in shape: long conical and flat, spirally twisted with a different number of chambers. Among them there were also giants up to 4-5 m (Endoceras), which led a benthic lifestyle. Nautilids underwent several periods of prosperity and decline in the process of historical development and have existed to this day, although they are now represented by only one genus, Nautilus.

In the Devonian, in parallel with the nautilids, a special group of cephalopods began to be found - bactrites (Bactritoidea), smaller in size and less specialized than the nautilids. It is assumed that this group of cephalopods descended from common as yet unknown ancestors with nautilids. Bactrites turned out to be an evolutionarily promising group. They gave rise to two branches of cephalopod development: ammonites and belemnites.

The subclass of ammonites (Ammonoidea) appeared in the Devonian and died out at the end of the Cretaceous. During their heyday, ammonites successfully competed with nautilids, whose numbers were noticeably declining at that time. It's hard for us to judge the benefits internal organization ammonites only from fossil shells. But the ammonite shell was more perfect,

Rice. 246. Fossil cephalopods: A - ammonite, B - belemnite

than that of nautilids: lighter and stronger. The partitions between the chambers of ammonites were not smooth, but wavy, and the lines of the partitions on the shell were zigzag, which increased the strength of the shell. Ammonite shells were spirally twisted. More often, the whorls of the spiral of ammonite shells were located in one plane, and less often they had the shape of a turbo-spiral (Fig. 246, A). Based on some body imprints of the fossil remains of ammonites, it can be assumed that they had up to 10 tentacles, possibly two ctenidia, beak-shaped jaws, and an ink sac. This indicates that ammonites apparently underwent oligomerization of metameric organs. According to paleontology, ammonites were more ecologically diverse than nautilids, and included nektonic, benthic and planktonic forms. Most ammonites were small in size, but there were also giants with a shell diameter of up to 2 m. Ammonites were among the most numerous marine animals in the Mesozoic, and their fossil shells serve as guiding forms in geology for determining the age of strata.

Another branch of cephalopod evolution, hypothetically derived from bactrites, was represented by the subclass of belemnites (Belemnoidea). Belemnites appeared in the Triassic, flourished in the Cretaceous and died out at the beginning of the Cenozoic era. In their appearance they are already closer to modern subclass Coleoidea. In body shape they resemble modern squids (Fig. 246, B). However, belemnites differed significantly from them in the presence of a heavy shell, which was overgrown with a mantle. The belemnites shell was conical, multi-chambered, covered with skin. In geological deposits, remains of shells and especially their terminal finger-like rostrums, which are figuratively called “devil’s fingers,” have been preserved. Belemnites were often very large: their length reached several meters. The extinction of ammonites and belemnites was probably due to increased competition with bony fish. And in the Cenozoic, a new group of cephalopods entered the arena of life - coleoids (subclass Coleoidea), devoid of shells, with fast reactive movement, with a complexly developed nervous system and sensory organs. They became the “primates” of the sea and could compete on equal terms as predators with fish. This group of cephalopods appeared

in the Cretaceous, but reached its peak in the Cenozoic era. There is reason to believe that Coleoidea have common origins with belemnites.

Environmental radiation of cephalopods. The ecological radiation of cephalopods is presented in Figure 247. From primitive shelled benthopelagic forms capable of floating due to the hydrostatic apparatus, several paths of ecological specialization have emerged. The most ancient ecological directions were associated with the radiation of nautilids and ammonites, which swam at different depths and formed specialized shelled forms of benthopelagic cephalopods. From benthopelagic forms there is a transition to bentonectonic ones (such as belemnites). Their shell becomes internal, and its function as a swimming apparatus weakens. In return, they develop a main mover - a funnel. Later they gave rise to shellless forms. The latter undergo rapid environmental radiation, forming nektobenthic, nektonic, benthic and planktonic forms.

The main representatives of nekton are squid, but there are also fast-swimming octopuses and cuttlefish with a narrow torpedo-shaped body. The composition of nektobenthos mainly includes cuttlefish, often swimming

or lying on the bottom, to bentonecton - octopuses that crawl along the bottom more than swim. Plankton include umbrella-shaped, or gelatinous, octopuses and rod-shaped squids.

During the evolution of the animal world, a number of methods have been developed to increase the survival of offspring. One of them is the care of the parents for the young before and after birth. Some animals carry their young on their bodies, others build houses for them, and others feed their offspring.

Such parental care ensures an increased percentage of survival of the species, and for some species, the transfer of social experience. Most interesting cases Guardianship of “parents” will be discussed in this article.

Caring parents among fish

Most fish do not worry about their young: after laying their eggs in the water, the fish spread out into different sides. But in such fish, the survival of the species is ensured by a huge number of eggs. But among fish there are caring parents. For example, Nannostomus chooses dense algae or aquatic plants for laying, which will protect the eggs. Betta fish build a nest out of their own saliva! Usually the male does this: he fills his saliva with air and whips it into foam. In such a foam nest, the fry hatch - under the watchful supervision of the “father”, who remains with them until the cubs learn to feed on their own.

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Tropheus lay very few eggs - and in order to save their offspring they are forced to carry the eggs, and then the fry, in their mouths. But the cubs are comfortable and safe! Cichlids have become adept at laying eggs in the shells of bivalve mollusks.

Caring parents - mollusks

Not everyone knows that octopuses are the smartest creatures. The size of their brain is large, and the structure of their eyes resembles the complexity of the human organ of vision. Octopuses don't worse than people take care of their young. After mating, the male octopus soon dies, and the female looks for reliable shelter in the rocks, climbs there and lays eggs.

Class Cephalopods belongs to highly organized sea ​​mollusks. Scientists count about 675 modern species, as well as about 11 thousand extinct ones. They have 8 arms on their heads, and cuttlefish and squids have a pair of tentacles. The length of their body including tentacles can vary from 15 centimeters to 5 meters (in some squids up to 20 meters). Class cephalopods widespread in almost all seas of our planet. They live both at the bottom and in the water column (in upper layers are quite rare).

Cephalopods: behavior and lifestyle

These animals serve as food for many fish, as well as marine mammals. Some of them are edible and are considered commercial fish. Cephalopods include squid, cuttlefish, octopuses, and among the extinct ones it is worth noting belemnite, ammonite and others.

Cuttlefish

move reactively, i.e. they suck in and forcefully spit out water and glide through the waves like living rockets. All representatives who are included in class cephalopods - feed on fish, as well as other inhabitants of the seas. There are also cases when they eat their own kind (cases of cannibalism). But one of the strangest habits of cephalopods can be considered eating their own body.

Sometimes there have been cases where octopuses that were kept in captivity suddenly began to eat themselves, biting off their tentacles, and then died. It is worth noting that class cephalopods They also have such a “means” for protecting themselves from enemies as tearing off their limbs. If an octopus hiding in its hole is caught by a tentacle, it will immediately “throw off” it.

Octopus

When any danger approaches, all cephalopods eject a stream of black caustic liquid into the water. This “ink” blurs in the water, and under this rather thick cloud of black color the mollusk safely hides or runs away.

Cephalopods are the real underwater brothers of chameleons: they can very quickly change the color of their skin. If you make an octopus very angry, it will instantly change gray of its cover to black, and when it calms down, it will turn gray again to the previous normal color of its body.

Cuttlefish

Cephalopods: nautiluses

Among the simplest animalsclass cephalopods shellfish are nautiluses, or otherwise pearl ships. It is worth noting that nautiluses, compared to most cephalopods, have a multi-chambered shell. In the process of growth, this mollusk builds for itself the most spacious and comfortable chambers of its “house” and tries to “settle” in the largest of them - that is, in the very last one.

By filling the remaining chambers with air or water, it can easily float up or sink to the very bottom. From the shell, these pearl ships are able to make “decorations” - the so-called buttons.

Nautilus

Octopuses

Class cephalopods includes marine animals with eight limbs. One of the most remarkable traits of common octopuses is the selfless care they take for their young. Female octopuses take great care of their offspring, vigilantly guarding the laid eggs.

Octopus

Cuttlefish

These animals literally “left their mark” on modern human culture. For a long time, almost all people wrote with its ink. The well-known “bone” (remnant of the head shell) of cuttlefish is no less valuable - it is collected on the sea coast.

It is used as a drawing eraser and, when crushed, as a tooth powder additive and as a medicine.

Cuttlefish

Squid

Interestingly, squids can not only swim well, but also fly. True, not many people know that they are capable of flying. It is important to note that these representatives class cephalopods They fly out of the water to independently overtake prey or to escape from numerous enemies.

The length of such flying squids is quite small - approximately 20 centimeters. Deep-sea squids also amaze with their very complex structure, as well as the size of their own eyes. In some animals of this class they can reach 40 centimeters in diameter. In general, squids pose plenty of mysteries for modern scientists.

Squid

For centuries, legends about giant colossal squids living in the depths of the sea have not been forgotten. And it should be noted that these legends are not without foundation, since the largest and largest mollusks are giant squid, which belong to the class Architeuthis and can sometimes grow up to 25 meters in length, and they weigh about 2.5 tons.

These are the amazing creatures related to class cephalopods , live in the World Ocean. Surely they will present many more surprises to scientists who have been studying them for many decades.

Giant squid

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