Starfish urchins cucumbers. Type echinoderm

Echinoderms are an ancient group of invertebrates that consists exclusively marine organisms living in water with high salinity. In some respects they are close to the phylum chordates. So, for example, echinoderms are typical deuterostome animals, they have a secondary body cavity - the whole, structure skin similar to the cover of chordates. The evolution of echinoderms was very complex and was accompanied by a change of forms, the extinction of some groups, and the transformation of others. Paleontological materials indicate that echinoderms obviously existed already in the Precambrian, since in subsequent geological periods they were quite widely represented. Based on the totality of scientific data on the origin of echinoderms, there is reason to assume that the ancestors of echinoderms were free-living, bilaterally symmetrical animals, which in the process of evolution acquired radial symmetry in connection with the transition to an attached lifestyle. Subsequently, echinoderms returned to free movement, maintaining a symmetrical radial structure, and only crinoids partially continue to lead an attached lifestyle.

Thus, radial symmetry in echinoderms is a secondary phenomenon. This is confirmed by their progress individual development: in ontogenesis they go through the larval stage (dipleuroles) with bilateral symmetry, and not with radial symmetry, which is characteristic of adult individuals. Here there is a connection between ontogenesis and phylogeny.

In their structure, echinoderms represent a very unique specialized group of animals. Unlike all other invertebrates, they have a special water-vascular system - ambulacral. None of the other types of animals have such a system. Its structure and functions are set out in a school zoology textbook, and there is no need to repeat it here. It is easy to see that the structure of this system and the arrangement of other organ systems of echinoderms bears the stamp of radial symmetry. The nervous system, for example, consists of three tiers, consisting of rings and radial trunks extending from them, of which the ring and trunks of the outer (superficial) tier are associated with sensory organs, which in echinoderms are generally poorly developed. For example, they have no phonoreceptors at all; the organs of touch, smell and taste are sensory cells on the ambulacral legs, on the oral tentacles and other parts of the body; the organs of vision are presented in the form of eye pits (in starfish), photosensitive organs (in sea cucumbers), age spots(in sea urchins); stator receptors in the form of otocysts are present only in some species of holothurians. Despite their modest receptor apparatus, echinoderms react quite strongly to changes in illumination and perceive taste stimulation well.

Assessing the behavior of echinoderms, it should be noted that it has reached significant diversity, which is associated with a more developed nervous system compared to other animals that have a radial type of body structure. In echinoderms, the number of interneurons increased, which improved and refined the connections between the sensory and motor apparatus, and this had great value in conditions of the disappearance of direct contacts between their sense organs and working tissues, since the nervous network of echinoderms moved from the surface to deeper parts of the body and turned into radial nerve cords without the formation of a compact nerve center.

Echinoderms live in seas and oceans of all latitudes on a wide variety of soils and at various depths (from the littoral zone to the deepest depressions). Their free-swimming larvae play a role in the settlement of echinoderms. However, the penetration of these animals into certain parts of the World Ocean depends primarily on the salinity and salt composition of the water. Echinoderms are especially abundant in the Red Sea with high salinity. There are also many of them in the salty seas Arctic Ocean- Okhotsk, Chukotka, Kara, Barents. Only 8 species live in the less saline Black Sea, and 1 species in the Baltic Sea.

Echinoderms reproduce both sexually and asexually. Caring for their offspring manifests itself in the form of the mother carrying eggs or young in certain areas of her body. Echinoderms living in the polar seas are characterized by viviparity (bypassing the larval stage). At unfavorable conditions or when attacked by enemies, echinoderms resort to autotomy with subsequent regeneration of lost parts.

Large sea ​​urchins can live up to 35 years, starfish- more than 14 years, brittle stars - up to 5 years.

Currently, there are about 6,000 species of echinoderms, which play a significant role in the cycle of substances in the seas and oceans, in changes in their salt composition and in the food chains of aquatic organisms. Ground-eating echinoderms use small animals living in bottom sediments as food, sea urchins eat algae, predatory starfish feed on fish, mollusks, sea urchins, coral polyps etc. In turn, echinoderms are included in the food supply of some fish (for example, catfish, cod, etc.), and in tropical seas - stingrays. A prominent place among the enemies of echinoderms is occupied by spiny lobsters, which are especially willing to eat brittle stars and sea lilies, but they also attack other echinoderms - sea urchins, sea stars and sea cucumbers.

Echinoderms have a certain practical significance. For example, sea cucumbers and sea urchin caviar are eaten; fossil echinoderms (their skeletal remains) form limestones and marble, used as building material, and sea urchins are the subject of various biological studies.

Phylum Echinodermata combines five classes modern species, among which the largest in terms of the number of species is the Ophiura class.

sea ​​lilies- a group of echinoderms whose body shape resembles a flower. The class unites about 620 species of animals with bright colors that live exclusively in the seas and oceans. Among sea lilies, there are representatives that lead an attached lifestyle (stem lilies), and there are those that can slowly swim and crawl (stemless lilies). The body of sea lilies has the shape of a cup, in the center of which there is a mouth. Five rays (arms) extend from the calyx, each of which bifurcates or divides many times. The difference between lilies and other echinoderms is that their body is directed with the cavity (oral) side up, and not down. Another feature of crinoids is the well-developed limestone skeleton, consisting of large plates various shapes and sizes. For attachment (in stalked parts) or for movement (in stalkless parts), root-like movable outgrowths extend from the stems or from the calyx - Tsire. A typical representative of stemless lilies is heliometer cold water, distributed in all Arctic seas, in the Japanese and Okhotsk seas

Sea lily ptilomera

seas and northern part Atlantic Ocean. This is a ten-promeneva yellowish lily with rays up to 35 cm long, in some places it forms real thickets.

Holothurians, or sea cucumbers, are a group of free-living echinoderms with an elongated cylindrical or worm-like body, which contracts very much at the slightest irritation. The class unites about 1,200 species of animals, distributed throughout all seas and oceans. Holothurians can withstand desalinated waters better than other echinoderms, which is why they are also found in the Black Sea (8 species). A characteristic feature Holothurians have tentacles that surround the mouth and are modified ambulacral legs. their number ranges from 8 to 30 and are designed to collect nutrient particles, as well as for movement, perception of touch and breathing. Another feature of holothurians is a soft skin-muscular sac and a highly reduced skeleton (only some species have an exoskeleton with plates). Holothurians are detritivores by their feeding method. One more unusual feature Holothurians have cuvian organs and water lungs. Cuverov's organs They are internal glandular tubular formations that flow into the cloaca. When an animal is irritated, they are able to shoot out through the cloaca and stick and confuse predators. Water lungs They look like two branched trunks with lateral extensions. In the rear part they are connected and by a common strait they open into the cloaca. The walls of the water lungs have well-developed muscles, thanks to which water is either drawn through the cloaca into the lungs or pushed out of them. The ability to regenerate is very well developed in holothurians. Representatives of sea cucumbers are edible sea cucumbers ( Far Eastern sea cucumber), sea cucumbers ( Japanese sea cucumber, or cucumaria, tricolor sea cucumber), legless holothurians ( leptosynapta small), true holothurians ( sand sea cucumber up to 30 cm long), etc.

Sea urchins - a group of free-living echinoderms whose bodies are predominantly spherical, slightly flattened at the poles. The class includes about 900 species, distributed mainly in warm seas. Absent in the seas of Ukraine. The entire body of hedgehogs is covered with a continuous shell of limestone plates. Only two areas - around the mouth and anus - remain soft. On the surface of the shell are tubercles to which spines and pedicellaria are attached. Needles can be long (in tiara more than 30 cm), pedicellaria have heads with sharp-toothed 2-4 valves, and often a poisonous gland. In their mouths, sea urchins have a gnawing apparatus called Aristotle's lantern. It consists of movably connected plates with denticles. With their help, these animals can eat algae and gnaw holes in rocks for protection from wave impacts, as does rock sea urchin Sea urchins lay 10-60 million eggs. There are two subclasses in the class - regular sea urchins ( black, edible, coastal, tiaras etc.) And irregular sea urchins (for example, flat, heart-shaped, ovoid and etc.).

Starfish - a group of free-living echinoderms whose body has the shape of a flattened five-rayed, sometimes multi-rayed, star or pentagon. The class unites about 1,700 species, distributed in waters of high salinity (over 30 ppm) from the coast of Antarctica to the equatorial waters of the World Ocean. stars

may have unusual shape, for example, a small pillow ( New Guinea culcites). A real giant among the stars is pycnopodia(Pycnopodia helianthoides), living on the rocky coastal areas of the northern part Pacific Ocean. Normal view shallow seas temperate zone northern hemisphere is asterias red, the length of the rays reaches 30 cm. One type of star lives in the Black Sea. Sea stars are often brightly colored and lead a bottom-dwelling lifestyle. According to their feeding method, they are predominantly predators that feed on sponges (for example, blood star), worms, mollusks, crustaceans, then echinoderms (brittle stars, sea urchins feed on sea stars of the genus Luidius), as well as fish. Starfish can open the valves of shells and push their stomach inside through the gap and gradually digest the body of the mollusk. So, in starfish there is external digestion. The most aggressive and voracious stars are crossaster(Crossaster papposus) and (Acanthaster plansi). The fertility of sea stars is very high and can amount to up to 200 million eggs.

Brittle stars- a group of free-living echinoderms with a pentagonal flattened body and long, sharply separated from the disk, thin articulated mobile rays. The class unites about 2000 species of animals that live on the seabed and are mobile among echinoderms. In the Black Sea, 4 species are common (for example, Amphiura Stepanova, Ophiothrix brittle). The rays are often simple and there are 5 of them, but there can be from 6 to 9. They are quite long, several times the length of the disk. The size of the disc is usually small (from a few millimeters to 2 cm), less often large (up to 10 cm). In some species (for example, Chairman of the Gorgon) the rays branch and form a complex plexus. Characteristic feature brittle star is that the rays have a well-developed external (from limestone plates) and internal skeleton(consists of vertebrae connected by muscles and ligaments). On the ventral side of the beam there are openings for the exit of the ambulacral legs. They serve as organs of breathing and touch. The outer disk of brittle stars is also covered with limestone plates that look like scales. Among them, large paired plates - radial scutes - stand out on the dorsal surface. On the ventral side there is a pentagonal mouth opening, which has 5 projections - jaws. Darterwhistles are often brightly colored. There are shapes that glow green.

Echinoderms (Echinodermata)- a type of sea animal that includes: starfish, sea lilies, sea urchins, brittle stars and sea cucumbers. We know about 6,000 living species of echinoderms. Most echinoderms are benthic animals that have a variety of feeding habits, including water filtration, carrion eating, and predation. Modern echinoderms, despite the fact that they evolved from sedentary ancestors, are capable of moving.

Echinoderms have an endoskeleton consisting of calcareous plates. In sea stars and brittle stars, the plates have a flexible structure. In sea urchins, the plates are fused together, giving the animals a rigid frame structure.

Echinoderms have predominantly pentaradial symmetry, due to which their body is divided into five equal parts around a central axis. Echinoderms developed this symmetry through evolution based on the bilateral symmetry possessed by their ancestors. For this reason, the radial symmetry of echinoderms does not mean that they are closely related to other organisms with this type of symmetry, such as cnidarians.

Main Features

Key characteristics of echinoderms include:

• calcareous endoskeleton consisting of plates or bones;
• radial (five-ray) symmetry;
• water-vascular system;
• pedicellaria (small claws with a skeletal structure used by sea urchins and stars to clean and capture prey);
• cutaneous gills (skin tubercles used to absorb oxygen from water).

Classification

Echinoderms are divided into the following taxonomic groups:

• sea ​​lilies (Crinoidea);
• starfish (Asteroidea);
• Brittle stars (Ophiuroidea);
• Sea urchins (Echinoidea);
• Holothurians (Holothurioidea).

Echinoderms are peculiar animals. They cannot be compared in structure with other types. These animals resemble a flower, a star, a cucumber, a ball, etc.

History of the study

The ancient Greeks gave them the name “echinoderms.” Representatives of this species have long been of interest to humans. The history of their study is connected, in particular, with the names of Pliny and Aristotle; and in the 18th and early 19th centuries they were studied by many famous scientists (Lamarck, Linnaeus, Klein, Cuvier). most zoologists at that time correlated them with either coelenterates or worms. I. I. Mechnikov, a Russian scientist, found out that they are related to the colibranchids. Mechnikov showed that these organisms are closely related to representatives of chordates.

Diversity of echinoderms

Nowadays, it has been established that echinoderms are animals that belong to the group of the most highly organized invertebrates - deuterostomes. They appeared on our planet more than 520 million years ago. The remains of echinoderms are found in sediments dating back to the Early Cambrian. This type includes about 5 thousand species.

Echinoderms are benthic, the main part of which are free-living organisms. Less common are those attached to the bottom with a special stalk. The organs of most organisms are located along 5 rays, but their number in some animals is different. It is known that the ancestors of echinoderms had bilateral symmetry, which free-swimming larvae possess among modern species.

Internal structure

Representatives of echinoderms develop a skeleton in the subcutaneous connective layer, consisting of calcareous plates and needles, spines, etc. on the surface of the body. Like chordates, in these organisms the secondary body cavity is formed by separation of mesodermal sacs from the intestine. During their development, the gastropore becomes overgrown or transforms into the anus. In this case, the larva's mouth is formed anew.

Echinoderms have circulatory system. However, their respiratory organs are rather poorly developed or absent altogether. It is necessary to briefly describe other characteristics of echinoderms. These animals do not have special ones. Quite primitive nervous system organisms of interest to us. It is located partially in the skin epithelium or in the epithelium of invaginating areas of the body.

External structure

The characteristics of echinoderms should be supplemented by features external structure these organisms. The outer epithelium of the majority of echinoderms (with the exception of holothurians) has cilia, which create a flow of water. They are responsible for supplying food, gas exchange and cleansing the body of dirt. In the integument of echinoderms there are various glands (causing luminescence and poisonous) and pigments that give amazing colors to these animals.

The skeletal elements of sea stars are calcareous plates, which are arranged in longitudinal rows, usually with spines protruding outward. The body of sea urchins is protected by a calcareous shell. It consists of a series of plates tightly connected to each other, with long needles sitting on them. Holothurians have calcareous bodies that are scattered across their skin. The skeleton of all these organisms is internal in origin.

Musculature and ambulacral system

The musculature of these animals is represented by muscle stripes and individual muscles. It is developed quite well, to the extent that this or that animal is mobile. In most species of echinoderms, the ambulacral system serves for touch and movement, and in some sea urchins and crinoids it is used for respiration. These organisms are dioecious; they develop with larval metamorphosis.

Classification of echinoderms

There are 5 classes of echinoderms: Brittle stars, Starfish, Sea urchins, Sea lilies and Holothurians. The phylum is divided into 2 subphyla: freely moving echinoderms are represented by brittle stars, holothurians, sea urchins and starfish, and attached ones - by crinoids, as well as some extinct classes. About six thousand modern species are known, as well as twice as many more extinct. All echinoderms are marine animals that live only in salt water.

Starfish

The most famous representative of the type we are interested in is the starfish (a photo of one of them is presented above). These animals belong to the class Asteroidea. It is no coincidence that starfish received this name. In their shape, many of them are a five-pointed star or a pentagon. However, there are also types whose number of rays reaches up to fifty.

Look what interesting body has a starfish, the photo of which is presented above! If you turn it over, you can see that from the underside of the rays there are rows of small tube legs with a suction cup at the end. The animal, moving through them, crawls along the seabed and also climbs vertical surfaces.

All echinoderms have the ability to quickly regenerate. In a starfish, every ray that has separated from the body is viable. It immediately regenerates and a new organism emerges from it. Most starfish feed on leftovers organic matter. They find them in the ground. Their diet also includes fish corpses and algae. However, some representatives of sea stars are predators that attack their prey (stationary invertebrates). After the prey is found, these animals dump their stomachs out. Thus, digestion in some predatory starfish is carried out externally. The rays of these animals have very powerful muscles. It allows them to easily open the valves of the mollusk. Starfish can, if necessary, crush its shell.

The most famous among them is Acanthasterplanci - crown of thorns. This worst enemy sea ​​coral reefs. There are about 1,500 species in this class (phylum Echinodermata).

Starfish are capable of reproducing both sexually and asexually (regeneration). The main part of these animals are dioecious organisms. Fertilization occurs in water. The body develops through metamorphosis. Some starfish live up to 30 years.

Dartertails (brittle stars)

These animals are very reminiscent of stars: they have thin and long rays. Brittle stars (a type of echinoderm) do not have hepatic appendages, anus, or hindgut. In their lifestyle they are also similar to starfish. These animals are dioecious, but are capable of both regeneration and asexual reproduction. Some species are luminous forms.

The body of the darter (brittle star) is represented by a flat disk, the diameter of which is up to 10 cm. 5 or 10 thin long segmented rays extend from it. Animals use these bending rays to move, with which they crawl along the seabed. These organisms move in jerks. They extend two pairs of their “arms” forward, after which they sharply bend them back. Dartertails feed on detritus or small animals. Brittle stars live on the bottom of the sea, sponges, corals, and sea urchins. There are about 2 thousand species. These animals have been known since the Ordovician.

sea ​​lilies

Echinoderms are very diverse. Examples of crinoids that also belong to this type are presented above. These organisms are exclusively benthic. They lead a sedentary lifestyle. It should be emphasized that crinoids are not plants, but animals, despite their name. The body of these organisms consists of a calyx, stem and arms (brachioles). They use their hands to filter food particles from the water. Most modern species are free-swimming and stemless.

Stemless lilies can crawl slowly. They are even able to swim in water. Their diet consists of small animals, plankton, and algae remains. Total number species are estimated at 6 thousand, of which less than 700 are currently represented. These animals have been known since the Cambrian.

Beautifully colored species of sea lilies live mainly in the seas and oceans of the subtropics. They attach to various underwater objects. It is believed that this is, however, in the Mesozoic and Paleozoic era their role in the waters of the seas and oceans was very great.

Sea cucumbers (holothurians)

These organisms are called differently: sea capsules or sea cucumbers. They represent a class of invertebrates such as echinoderms. There are species that humans eat. The common name for edible sea cucumbers is sea cucumber. Sea cucumber is mined on a large scale in Far East. There are also poisonous sea cucumbers. From them various medicines(for example, holothurin).

There are currently about 1,150 species represented sea ​​cucumbers. Their representatives are divided into 6 groups. The Silurian period is the time to which the oldest holothurian fossils date.

These organisms differ from other echinoderms in their oblong, spherical or worm-like shape, as well as in the reduction of the dermal skeleton and the fact that they do not have protruding spines. The mouth of these animals is surrounded by a corolla consisting of tentacles. With their help, sea cucumbers capture food. These animals are bottom-dwelling, although very rarely they are also found living in mud (pelagic). They lead a sedentary lifestyle. Holothurians feed on small plankton or mud.

Sea urchins

These animals live at the bottom or near the bottom. The body of most of them is almost spherical, sometimes ovoid. Its diameter ranges from 2-3 to 30 cm. The outside of the body is covered with rows of spines, calcareous plates or needles. As a rule, the plates are fixedly connected to each other, forming a shell (dense shell). This shell prevents the animal from changing shape. Today there are about 940 species of sea urchins. Largest quantity species were represented in the Paleozoic. There are currently 6 classes, while there are 15 extinct classes.

As for feeding, some sea urchins use dead tissue (detritus) as food, while others scrape algae from rocks. In the latter case, the animal's mouth is equipped with a special chewing apparatus, which is called the Aristotelian lantern. In appearance it resembles a drill. Some species of echinoderms (sea urchins) use it not only to obtain food, but also to modify rocks by drilling holes in them.

The value of sea urchins

These animals are valuable species marine biological resources. Commercially it is interesting mainly in Japan and other countries of the Asia-Pacific region, it is a delicacy product. The caviar of these animals contains many biologically active substances. Scientists believe that the elements contained in it can be used in cancer diseases as a therapeutic and prophylactic agent. In addition, they normalize blood pressure, increase potency, and remove radionuclides from the human body. It has been proven that eating caviar increases resistance to various infections, helps with gastrointestinal diseases, reduces the effects of radiation therapy, improves the functions of the reproductive and thyroid glands, and the cardiovascular system.

Given the above, it is not surprising that the sea urchin is a marine echinoderm that is becoming a coveted dish. For example, residents of Japan eat about 500 tons of caviar from this animal every year, both in its natural form and as additives to dishes. By the way, with the use of this food product contacts like this long duration life in this country where people live an average of 89 years.

This article presented only the main echinoderms. We hope you remember their names. Agree, these representatives of marine fauna are very beautiful and interesting.

Holothurians, or sea pods, or sea ​​cucumbers(lat. Holothuroidea) - a class of invertebrate animals such as echinoderms. Species eaten as food are common name"trepang".

The modern fauna is represented by 1150 species, divided into 6 orders, which differ from each other in the shape of the tentacles and calcareous ring, as well as the presence of some internal organs. The oldest fossils of sea cucumbers date back to the Silurian period.

Despite the fact that holothuria is usually called sea ​​cucumber, this is a real animal belonging to a separate class of invertebrates such as echinoderms, like sea urchins, starfish, snaketails - brittle stars and sea lilies.

These unusual echinoderms sea ​​creatures They were also named by the ancient Greeks, and they were combined with either worms or coelenterates. Then names for this type of animal appeared, such as radiata, zoophytes, i.e. half-plants, half-animals (like sponges), and only at the end of the 19th century they were identified as an independent and unique type of animal under modern name echinoderms.

Currently, zoologists consider animals such as echinoderms to be the most highly organized representatives of invertebrates.

They can be found in many seas and oceans, from shallow coastal waters to deep-sea depressions (for example, deep sea species present in the genera Paelopatides and Paroriza). Sea cucumbers are most common in the waters of the tropics and subtropics, preferring to settle coral reefs and rocky soils overgrown with dense vegetation.

Holothurians are very ancient animals. The age of some fossilized remains that fell into the hands of specialists was estimated at 450 or even more million years. According to scientists, these animals appeared in the Cambrian period, that is, at least 500 million years ago.

Holothurians- absolutely unique animals. Like sea stars, urchins and brittle stars, they have a pronounced five-ray symmetry of the body, and move along the bottom on tiny tube-like legs, setting them in motion, pumping water through the channels of these tubes.

But there are also significant differences in the body structure and appearance of sea cucumbers and other echinoderms. They have an oblong body, resembling in shape either a cucumber or an oblong spheroid, and sometimes not even a long worm. There are no pronounced rays or long spines on the body of these animals.

Their skeletal lattice is represented by small calcareous formations in the form of blunt needles - spicules, located in the walls of the body. The spines of some species are sharp and hard, and you can even get hurt on them.

If you touch the skin of a sea cucumber with your hand, it will seem wrinkled and rough to the touch. The body is elastic, muscular, since five ribbons of longitudinal muscles are radially located in it, stretching from the mouth to the anus.

Around the mouth there is a crown of short tentacles, with which the holothurian captures prey and pulls it into the mouth. The tentacles are not capable of significant contractions, since they are not equipped with the appropriate muscles for this.

The esophagus of sea cucumbers has the appearance of a spirally wrapped intestine, surrounded by a calcareous ring, which serves as a support for the longitudinal muscles.

Holothurians reproduce by eggs. Individuals have sexual difference(males and females), but outwardly they are difficult to distinguish. Fertilization of eggs is most often external, but there are also species in which the offspring develop in the body of the female. Holothurians live on average 5-10 years.

Body coloration of sea cucumbers different types can be brown, brown-red (various shades), green, yellowish-green and even black or white. There is information that there are blue sea cucumbers, to which popular rumor attributes numerous medicinal properties bordering on the miraculous. Perhaps similar albinos do occur in nature, but the healing properties of their color are probably just a beautiful legend. The body color of sea cucumbers largely depends on their habitat - it has been noted that the skin color of these animals tends to harmonize with the color of the underwater landscape.

The body size of different species of sea cucumbers can vary from several centimeters to five meters (the record holder is the spotted synapta maculata), but most often there are individuals from 30 cm to a meter in length.

The lifestyle of sea cucumbers is inactive - they usually crawl slowly along the bottom, filtering edible organic particles from the soil. It is curious that they are located on their sides, since the ambulacral legs that serve them for movement are located on the side of the body. These primitive animals feed on small living organisms - benthos, i.e. plankton, which live in the bottom layers of water. But the basis of the diet of sea cucumbers is made up of the organic remains of dead organisms that constantly sink to the bottom from different depths. sea ​​waters. For this reason, holothurians are called the orderlies of the sea, and indeed, their role in cleaning the seabed from microscopic carrion can hardly be overestimated.

These animals have another amazing ability - they can turn their stomach out through the cloaca and throw out its contents, sometimes even with internal organs. Holothurians often use this technique in moments of danger, when they need to escape from the enemy. Since sea cucumbers move on their short legs slower than a turtle, then they have to sacrifice their entrails to distract the attention of the predator.
A unique abilities sea ​​cucumbers to regenerate body parts and even internal organs help them restore the loss in just two to three weeks. As they say, lizards are resting.

Natural enemies of sea cucumbers include starfish, some types of mollusks, predatory fish and crustaceans, which are indifferent to the toxins produced by sea cucumbers.

The poisonous filling of the stomach of many sea cucumbers makes it difficult to keep them in aquariums - they can destroy not only other pets of an artificial reservoir, but also die in a cloud of toxin. For this reason, it is not recommended for inexperienced hobbyists to place sea cucumbers in their aquarium.

Among these animals there are also edible species, which are called sea cucumbers (for example, many representatives of the genera Holothuria, Bohadschia, Actinopyga, Microthele, etc.).
Sea cucumbers are used as food by many Asian peoples (Japanese, Chinese, Malays, etc.) - they are caught commercially and served dried, smoked, boiled, fried or canned. There are even dishes made from raw sea cucumbers.

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