Sea cucumbers. Lifestyle and habitat of the sea cucumber Structure of holothuria

Sea cucumber, sea cucumber, sea pods - that's all different names one marine echinoderm invertebrate mollusk that looks like a fat caterpillar. There are over a thousand species of this mollusk, sea cucumber sea cucumber is a number of subspecies that are classified as edible and are used as food. Differences between species relate to the structure of the tentacles, size and internal organs.

These animals live in the depths of salty sea waters, the average depth at which they are found is about 100 m. The oval body of the mollusk can resemble a cucumber, it is covered with thick skin and spines, sometimes very similar to the pimples of a cucumber.

Appearance of holothuria

Holothuria is a unique mollusk that resembles both a worm and a caterpillar at the same time. Its body is soft, in some cases the skin can be smooth, in others it can be rough and have growths. Depending on the type, spines are short and long. The color of the sea cucumber also differs from one species to another, but dark tones predominate: gray, green, black, brown.

The variety of sizes of holothurians is impressive, the smallest representatives do not exceed 0.5 cm, and the largest ones can reach 5 meters! This is how they attract hunters of sea animals.

Sea cucumbers cannot chew or grind food; there are no teeth or other devices for this in the mouth. The mouth is located at the front end of the body. Some species resemble a ball or flask; they are able to attach to rocks or burrow into mud, this is possible due to the location of the mouth closer to the back.

A distinctive feature of holothurians is the presence of tentacles around the mouth, these are modified ambulacral legs. Their structure varies, and the number varies from 10 to 30 pieces. The function of the tentacles is to capture and catch food from the bottom or water space.

The fact that holothuria has such extraordinary look, does not make it difficult to determine the dorsal and abdominal areas by eye. The morphological structure of the sea cucumber's abdomen is strikingly different from other animals. Holothuria always moves on its side, so the names of the dorsal and abdominal regions do not quite coincide with the usual ideas about them.

The head and body of a sea cucumber are in most cases inseparable, but some forms of sea cucumber have noticeable boundaries that separate the head from the rest of the body. This is a very slow animal that moves by squeezing and unclenching. But it spends most of its life just lying on its side, so catching them is quite simple. To a large extent, catching consists of searching for the animal rather than actually catching it.

One of the species of Holothuria is the Giant California Sea Cucumber, an absolutely unique animal. Despite the fact that he has a completely normal mouth, he also uses his anus as a mouth. The respiratory tract of these animals also located in the anus. Therefore, it turns out that their anus performs three vital functions in the body.

There are cases where these animals reproduced asexually. When one organism was divided, both parts grew the missing parts, resulting in two full-fledged organisms.

Sea cucumber sea cucumber

Some species are called sea cucumbers sea cucumbers, which are used for food, there are at least 30 such species. They are caught mainly off the coast of Japan and the Malay Archipelago, but this is also possible in the Vladivostok area. This is a very nutritious product that has high a set of vitamins, proteins, amino acids and nutrients. At the same time, it is worth noting that low calorie content sea cucumbers

The composition of sea cucumbers includes:

Groups of vitamins A, C, E, PP.
Fluorine, iron, magnesium, calcium, cobalt, nickel, potassium and many other elements.

Holothuria is considered medicinal and restorative natural substance, which allows you to quickly get back on your feet after operations or serious illnesses. In oriental medicine, sea cucumber meat has long been used for metabolic problems, to increase blood pressure, and various heart diseases, as well as for tissue regeneration. It will be useful to take sea cucumber meat for iodine deficiency, endocrine disorders, and problems with the thyroid gland.

Sea cucumber renders positive influence on human health, so by including it in your menu, you can prevent many diseases. Also, sea cucumber will be useful for patients with arthritis, it is different beneficial influence on the joints, some elements from the composition of sea cucumber can eliminate pain and stiffness of the joints.

Not only meat is produced from this mollusk, but also a concentrated extract. Chinese doctors claim that this extract has the same properties as meat. But also, it significantly increases immunity, improves the functioning of the cardiovascular system, and helps keep the body in the necessary tone. Special recommendations for the use of hoods apply to pensioners and people suffering from chronic diseases.

But sea cucumber also has contraindications:

Hyperfunction of the thyroid gland.
Hypertension, a substance that increases blood pressure.
Not recommended for children under 15 years of age.
Seafood intolerance.

Cooking sea cucumber

There should be no problems with preparing these shellfish; it is not difficult.

You should start by preparing the dried product, washing it thoroughly until there is no trace of the black powder left. Then it is left to soak in water, the water needs to be changed from time to time. After that he cook for 3 hours. If the sea cucumber is fresh, it is washed and boiled for 2-3 hours until the meat is soft. Various dishes are prepared from boiled meat.

There are a huge variety of dishes that can be prepared from sea cucumber. It can be various soups and salads, you can stew it with vegetables, chicken or horseradish, fry it with onions or tomato sauce. Hot sauces go best with shellfish dishes.

For example, sea cucumber with honey has gained high popularity among lovers of delicacies not only for its taste, but also for its unique beneficial properties for the body.

If you come across a product that is too dry, it should be soaked for several days. Readiness for cooking is determined by the purity of the water when rinsing; if the water is completely clean, you can start cooking.

Storage conditions for dry sea cucumber are standard: dark and cool place, without access sun rays. Cooked or fresh product can be placed in the freezer, but if it spends there for more than 2 months, it will lose its properties. healing properties.

Japanese chefs prepare sea cucumbers raw. Having previously cleaned and washed it, cut it into pieces and pour vinegar or sauce over it.

Recently, canned sea cucumber has gained popularity; many global companies have already launched conveyor production of canned sea cucumber. For this purpose, they even began to artificially breed it on special farms.

At first glance, it is difficult to assume that sea cucumber is edible; some may even find it disgusting to look at. But after studying it in more detail, it turns out very useful product, which will help tone the body and protect against various diseases. Finally, it can simply become a tasty and satisfying dinner, while at the same time being a dietary product.

Sea cucumber (sea cucumber) or sea cucumber (lat. Holoturoidea) is an invertebrate animal belonging to the echinoderm type. The most famous representatives: Japanese and cucumaria. The creature is unique in its structure, appearance, protective capabilities, and also has a number of useful substances. They are actively used for medicinal purposes, and sea cucumber meat produces delicious dietary dishes. In ancient China, the animal was called “sea ginseng”.

How many and what types of sea cucumbers are there?

Number of species: 1100.

There are 6 squads:

Squad	Peculiarities
Legless	Ambulacral legs are absent. They feel great in freshwater environments. Habitat: mangrove swamps of the Egyptian national reserve Ras Mohammed (translated as “Cape Mohammed”).
Sidefoot	Body symmetry is bilateral. The ambulacral legs are located on the side of the body. They live on great depth.
Barrel-shaped	The body shape is spindle-like. Adapted to life in the soil.
Tree-tentacled	It has the greatest number and prevalence. Lifestyle – sedentary.
Thyroid-tentacles	Small shield-like tentacles that do not retract inward.
Dactylochirotids	The tentacles are finger-shaped.

Scientists have identified sea cucumbers in the Caribbean Sea that are significantly different from their counterparts. Enypniastes eximia or pink sea cucumber resembles a jellyfish in appearance. Biologists jokingly call it the “headless chicken.” Bioluminescence, movement in the water column (able to swim up to 1 km) are the special abilities of this representative.

What they look like

Those who see sea egg capsules for the first time describe them as large earthworms or snails without a shell.

The animal has its own distinctive features from other invertebrate representatives:

The body of the holothurian is oblong, trapezoidal, slightly flattened laterally. It has thick, elastic walls. Represented by the musculocutaneous sac. If you take a closer look at the animal, you can see a mouth with tentacles and an anus. The body of the holothurian consists of two parts: dorsal and abdominal.
The surface is rough when touched and externally wrinkled.
Color: black, red, green.
The length for each representative is different: from 3 cm to 2 m. There are exceptions to the rules, for example, Synapta maculate reaches 5 m.
The weight of an adult can reach up to 1.5 kg.

It should be noted that the sea cucumber has the ability to regenerate. If there is a violation of the integrity of the skin bag, over time, the lost or damaged area is restored.

The structure of holothuria

1	Ampoules
2	Gonad
3	Longitudinal muscle
4	Cloaca
5	Airways
6	Longitudinal muscle
7	Introverted retractor muscle
8	Stomach
9	Esophagus
10	Pharynx
11	Tentacles
12	Round channel
13	Bubble
14	Introverted retractor muscle
15	Intestines

The skeleton is represented by calcareous bones.

The muscular frame consists of 5 longitudinal muscles that are attached around the esophagus. One end of the body is represented by the mouth, from which there is a spiral intestine, the second - by the anus.

Breathing is carried out using the ambulacral system and water lungs, which open into the cloaca in front of the anus.

The blood circulation system is highly branched. The greatest concentration of blood vessels is observed near the intestines. Oxygen saturation of the blood occurs through the vessels that surround the left lung. The vessels from the right lung go to the entire body.

Nervous system: peripharyngeal nerve ring and 5 radially located nerves. The sense organs are tentacles, and the balance organs are statocysts.

Ambeocytes are present to secrete the final products of metabolism.

The gonad is a reproductive organ resembling finger-shaped tubes.

Where does the sea cucumber live?

Main locations: China, Japan, Malay Archipelago, Pacific waters, near the Philippine Islands.

The Far East is a place where active fishing for cucumaria and Japanese sea cucumber takes place.

Sea pods prefer warm, shallow places, hiding in algae or in the surface layers of silt. IN fresh water the animal does not live (with the exception of representatives of the legless order).

Features of behavior and movement

Holothurians live in herds, but move independently, alone. Depending on the presence and length of the ambulacral legs, the speed and ability to move is different for each person. Some individuals do not have special outgrowths, so they move using peristaltic movements, pushing off the surface with calcareous bones.

Lifestyle and diet

In most cases, the animal is inactive, therefore it is easy prey for other inhabitants of the seabed (crustaceans, fish, starfish). To protect itself when attacked, the holothurian throws out the back part of its internal organs. This creates a distraction and allows the front of the sea cucumber to hide. Complete regeneration occurs after 6-8 weeks.

Dangerous or not

The sea capsule lives in symbiosis with fish. They are located inside the animal, namely, in the anus and water lungs. The release of toxic substances occurs solely for protection.

So is it poisonous or not? Some species are capable of secreting toxic cuvier tubes when necessary. The poison is only dangerous for small marine animals. Sea egg pods are completely safe for humans.

What does it eat?

Plankton and organic particles are the basis of holothurian nutrition. By passing water through the tentacles, microorganisms and plankton are retained in the animal’s mouth. To do this, there are 10-30 tentacles that are placed around the mouth.

Researchers claim that sea cucumbers have a bipolar apparatus for feeding. In other words, food enters in two ways: through the mouth and the anus.

The search for food is carried out in the evening or at night. In the autumn-winter period, sea cucumbers practically do not eat. Intensification of the search for food occurs at the beginning of spring.

After spawning, males hibernate to recuperate and eat almost nothing. Then, having woken up, they begin an active search for food.

Reproduction

Spawning time: June – September.

During fertilization, the male and female individuals stretch upward, assuming a vertical body position, and begin to sway. The process begins when the exchange of reproductive products takes place at the connection of the genital openings.

Among the representatives there are unisexual (synthesize male and female sex hormones) and dioecious. The maturation of male germ cells and eggs occurs in the gonads, then the reproductive products are released out through the genital duct.

In most holothurians, the process of conception and development of the embryo is external. With the help of tentacles, the eggs are attached to the dorsal part of the body. Sometimes the formation of an embryo occurs inside an adult. The eggs become larvae - dipleuroles. After a few days they turn into auricularia, and then into dolioralia, vitellaria and penctatula.

The lifespan of holothurians is about 10 years.

Is it possible to breed sea egg pods in captivity?

Since sea cucumber is quite valuable and useful product, its populations are almost destroyed in wildlife. That is why sea cucumbers are bought exclusively from farms where they are grown individually. Sea cucumbers are bred in Russia, Far East.

Is it possible to keep sea cucumber at home?

Chemical composition

Sea cucumber contains dietary protein. Rich in amino acids, macro and microelements: potassium, magnesium, iodine, fluorine, cobalt, copper, bromine, chlorine, nickel, calcium, iron. Also present are dietary fiber, polyunsaturated fatty acids, vitamins B, C, and nicotinic acid (PP). Acidity is 15.95.

Useful properties in medicine

The benefits of eating sea cucumber meat have a positive effect on health:

Speeds up the recovery period after surgical intervention or illness.
Far Eastern medicine has been using raw sea cucumber meat for many years to normalize metabolism and lower blood pressure.
It has a positive effect on arthritis (inflammation of the joints).
Sea cucumber extract has a good effect on the nervous and cardiovascular systems.
Cosmetology uses preparations based on sea cucumber for rejuvenation procedures.
Improves the functioning of the endocrine system.
Since ancient times, sea cucumber has been considered a strong aphrodisiac. It was used to treat prostatitis in men, as well as restore male sexual function.
Calorie content of 100 g of product: 35 kcal. Therefore, edible sea cucumbers are recommended for use by people who control their weight; they are excellent for weight loss.
The beneficial properties of sea cucumber in medicine are aimed at restoring the level of immune defense.
Depression goes away, fatigue disappears.

Contraindications

It should be remembered that for pregnant women, during breastfeeding, children under 15 years of age, as well as for hyperfunction (hyperthyroidism, thyrotoxicosis) of the thyroid gland, use is strictly prohibited.

What types of medications are there?

There are capsules, extract with honey, as well as extracts.

The form of the drug is selected individually.

Sea cucumber recipes

Before preparing it, you should know that dietary sea cucumber meat is quite specific - it is tasteless. Therefore, you should not expect taste pleasure from such food. But such dishes will bring enormous health benefits. The most famous recipes for preparing edible sea cucumbers:

Residents of Far Eastern countries eat raw sea cucumber. To do this, the carcass is thoroughly cleaned of entrails and washed. Then finely chop it and infuse it in soy sauce.
Skoblyanka is a hot dish, served on its own or as a side dish.

You will need:

Peeled, cut into pieces sea cucumber.
Onions
Salt, pepper, spices to taste
Tomato
Sunflower or butter.

Preparation:

Boil the carcass until soft. Fry the onion until golden, add boiled meat, salt, pepper, and tomato. After frying, let simmer for about 5 minutes. Add garlic if desired.

With vegetables it is quite a tasty dish and can be used as a side dish.

You will need:

Boiled sea cucumber meat 2-3 pcs.
Carrots 2 pcs.
Cabbage 200-300g
Onions 2 pcs.
Smoked chicken breast 100-150g
Green onions 3-4 feathers
Parsley
Ginger root 100g
Butter 6 tbsp.
Salt and pepper to taste.
Sesame 1-3 tbsp.

Preparation:

Boil the chopped meat and ginger. Mix chopped herbs with meat. Then send it to stew with the cabbage. After 5 minutes (or when the cabbage is ready), add the fried onions and carrots. Simmer over low heat until fully cooked for 10-15 minutes. Serve with sesame seeds.

Sea cucumber with honey – medicine. All useful properties are preserved. To prepare honey extract from sea cucumber yourself, cut the meat into half rings and dry. Add honey, maintaining a 1:1 ratio. Leave in a cool place for 2 months, stirring occasionally. Take 1 tbsp. 15-20 minutes before meals.

Sea cucumbers are echinoderms from the class Holothuroidea (Holothurians). These are marine animals with a leathery shell and an elongated body containing one branched gonad. Sea cucumbers live on the seabed. The number of sea cucumber species worldwide is about 1,717, with greatest number is located in the Asia-Pacific region. Many are harvested for human consumption, and some species are farmed in aquaculture systems. The harvested product is called differently - sea cucumber, bêche-de-mer or balat. Sea cucumbers play an important role in the marine ecosystem as they help recycle nutrients, break down detritus and other organic matter so bacteria can continue the breakdown process. Like all echinoderms, just below the skin, sea cucumbers have an endoskeleton, calcified structures that are usually reduced to isolated microscopic ossicles (or sclerieta) bound by connective tissue. In some species, they can sometimes be enlarged into flattened plates, forming a protective covering. In pelagic species such as Pelagothuria natatrix (order Elasipodida, family Pelagothuriidae), the skeleton and calcium ring are absent. Sea cucumbers are so named because of their resemblance to cucumber fruits.

Review

Most sea cucumbers, as their name suggests, have a soft and cylindrical body, more or less elongated, rounded and sometimes fuller in the limbs and usually without hard appendages. Their shape ranges from almost spherical in the "sea apples" (genus Pseudocolochirus) to serpentine in Apodida, or the classic sausage shape, while others are caterpillar-like. “The mouth is surrounded by tentacles that can be retracted into the animal.” Holothurians are usually from 10 to 30 centimeters in length, however, species measuring a few millimeters in size (Rhabdomolgus ruber) and up to more than 3 meters in length (Synapta maculate) are found. The largest American species, Holothuria floridana, which lives in abundance just below low water mark on the reefs of Florida, has a well volume of more than 500 cubic centimeters and a length of 25-30 cm. Most of them have five rows of tube feet, except the species Apodida, which moves by crawling ; the legs may be smooth or with fleshy appendages (for example, Thelenota ananas). The legs on the dorsal surface usually do not serve for movement and turn into papillae. A rounded mouth opens at one end, usually surrounded by a crown of tentacles, which can be very complex in some species (and they are actually modified legs); anus - retrodorsal. Holothurians do not look like other echinoderms at first glance, due to their tubular body, without a visible skeleton or rigid appendages. In addition, the fivefold symmetry, classic for echinoderms, although structurally preserved, is here doubled through bilateral symmetry, which makes them similar to chordates. However, central symmetry still observed in some species through five "radii" that extend from the mouth to the anus (just like sea urchins), to which tube feet are attached. Thus, these animals do not have any "front" or "dorsal" face, like starfish and other echinoderms, but the animal stands on one of its sides, and this face is called trivium (with three rows of tube feet), and the dorsal face called bivium. A remarkable feature of these animals is the “trapping” collagen that forms their body wall. It can be loosened and tightened at will, and if an animal wants to squeeze through a small gap, it can significantly compress its body. To keep itself safe in these cracks and cracks, the sea cucumber uses all of its collagen fibers to harden its body again. The most common way to separate subclasses is by the appearance of their oral tentacles. The order Apodida has a thin and elongated body, without tube feet, and up to 25 simple or feathery oral tentacles. Aspidochirotida are the most common sea cucumbers with a strong body and 10-30 leaf-shaped or shield-shaped oral tentacles. Dendrochirotida are biofilter feeders with plump bodies and 8-30 branched oral tentacles (which can be extremely long and complex).

Anatomy

Sea cucumbers are generally between 10 and 30 cm in length, although the smallest known species is only 3 mm in length, and the largest can reach three meters. The body can be almost spherical or worm-like, without legs, like many other echinoderms, such as the starfish. The anterior end of the animal, containing the mouth, corresponds to the oral pole of other echinoderms (which, in most cases, is the lower part), and the posterior end, containing the anus, corresponds to the dorsal pole. Thus, compared to other echinoderms, sea cucumbers can be said to lie on one side.

Body structure

The body of the holothurian is approximately cylindrical. It is radially symmetrical along the longitudinal axis and has weak bilateral symmetry transversely with the dorsal and ventral surface. Like other echinozoans, holothurians have five ambulacra separated by five ambulacral grooves, the mesambulacrum. The ambulacral grooves contain four rows of legs, but these are smaller or absent in some holothurians, especially on the dorsal surface. Two dorsal ambulacra make up the bivium, and three ventral ones make up the trivium. At the anterior end, the mouth is surrounded by a ring of tentacles that usually retract into the mouth. These are modified tube feet that can be simple, branched or tree-like. These are known as the proboscis, and at the back there is an inner ring of large calcium bones. Attached to them are five strips of muscles that run longitudinally along the ambulacra inside. There are also circular muscles, the contraction of which causes the animal to lengthen and the trunk to expand. In front of the bones lie further muscles, the contraction of which causes the trunk to retract. The body wall is composed of epidermis and dermis and contains smaller calcified ossicles, the types of which are characteristics that help identify different species. Inside the body wall is a secondary cavity divided by three longitudinal mesenteries that surround and support the internal organs.

Digestive system

Behind the mouth is the pharynx, surrounded by a ring of ten calcified plates. In most sea cucumbers, this is the only important part of the skeleton, and it forms the attachment point for the muscles that can retract the tentacles into the body for safety, as for the major muscles of the body wall. Many species have an esophagus and stomach, but some have pharynxes that open directly into the intestines. The intestine is usually long and coiled, and passes three times through the body to the cloacular chamber or directly into the anus.

Nervous system

Sea cucumbers do not have a true brain. A ring of nerve tissue surrounds the oral cavity and directs nerves to the tentacles and pharynx. The animal, however, is quite capable of functioning and moving if the nerve ring is surgically removed, suggesting that the ring does not play a central role in neural coordination. In addition, five major nerves run from the nerve ring along the length of the body under each of the ambulacral regions. Most sea cucumbers do not have distinct sensory organs, although they do have various nerve endings scattered throughout the skin, giving the animal a sense of touch and sensitivity to the presence of light. However, there are a few exceptions; Members of the order Apodida are known to have statocysts, while some species possess small eyespots near the bases of their tentacles.

Respiratory system

Sea cucumbers extract oxygen from water in a pair of "respiratory trees" that branch into a cloaca just inside the anus, so they "breathe" by drawing water in through the anus and then expelling it. The trees consist of a number of narrow tubes branching from a common duct and are located on either side of digestive tract. Gas exchange occurs through the thin walls of the tubules, into and out of the fluid of the main body cavity. Together with the intestines, the respiratory trees also act as excretory organs, with nitrogenous wastes being distributed along the walls of the tubules in the form of ammonia and phagocytic coelomocytes depositing the waste as particulates.

Circulatory systems

Like all echinoderms, sea cucumbers have both an ambulacral system, which provides hydraulic pressure to the tentacles and tube feet that allow them to move, and a hemal system. The latter is more complex than that of other echinoderms, and consists of well-developed vessels, as well as open sinuses. The central gemmal ring surrounds the pharynx adjacent to the annular canal of the ambulacral system and sends additional vessels along the radial canals beneath the ambulacral areas. In larger species, additional vessels flow above and below the intestines and are connected by more than a hundred small muscular ampoules that act like miniature hearts, pumping blood around the hemal system. Additional vessels surround the water lungs, although they connect them only indirectly, through the coelomic fluid. In fact, the blood itself is essentially identical to the coelomic fluid that directly bathes the organs and also fills the ambulacral system. Phagocytic coelomocytes, somewhat similar in function to the leukocytes of vertebrates, are formed within the hemal vessels and travel throughout the body cavity, as well as to both circulatory systems. An additional form of coelomocyte, not found in other echinoderms, has a flattened discoid shape and contains hemoglobin. As a result, in many (though not all) species, the blood and coelomic fluid are colored red. High concentrations of vanadium were found in the blood of sea cucumbers, but researchers were unable to reproduce these results.

Motor organs

Like all echinoderms, sea cucumbers have pentaradial symmetry. However, due to their body position, they have secondarily developed some degree of bilateral symmetry. For example, since one side of the body is usually pressed against a surface and the other is not, there is usually a difference between the two surfaces (except in Apodida species). Like sea urchins, most sea cucumbers have five striped ambulacral regions running the length of the body from the mouth to the anus. The three ambulacral areas on the lower surface have numerous tube feet, often with suckers, which allow the animal to crawl; they are called trivium. Two areas on the upper surface have underdeveloped or vestigial tube feet, and some species have no tube feet at all; this face is called the bivium. In some species, the ambulacral regions can no longer be distinguished, with the tube feet extending over a much wider area of the body. Apodida species have no tube feet or ambulacral regions at all and move by muscular contractions of the body, like worms, however, they typically have five ray lines running along their body. Even sea cucumbers, which do not have the usual tube feet, have feet around the mouth. They are modified into contractile tentacles much larger than tube feet for locomotion. Depending on the species, sea cucumbers have between ten and thirty of these tentacles, and they can have a wide variety of shapes depending on the animal's diet and other factors. Many sea cucumbers have papillae, conical fleshy projections of the body wall with sensory tube feet at the tops. They can even develop into long antenna-like structures, especially in the abyssal genus Scotoplanes.

Endoskeleton

Echinoderms typically have an internal skeleton composed of plates of calcium carbonate. However, in most sea cucumbers these plates have shrunk to microscopic bones under the skin. A few genera, such as Sphaerothuria, retain relatively large plates.

Life history and behavior

Habitat

Sea cucumbers are found in large numbers in the deep sea, where they often make up the majority of the animal's biomass. At depths greater than 8.9 km, sea cucumbers make up 90% of the total macrofauna. Sea cucumbers form large schools that move across the deep ocean, hunting for food. The body of some deep-sea holothurians, such as Enypniastes eximia, Peniagone leander and Paelopatides confundens, consists of tough gelatinous tissue with unique properties, which allows animals to control their buoyancy, allowing them to either live on the ocean floor, actively swim, or move to new places. Holothurians appear to be the best adapted echinoderms to extreme depths and are still very common at depths greater than 5000 m. Several species in the family Elpidiidae ("porpoises") can live at depths greater than 9500 m, and some species of the genus Myriotrochus (in particular, Myriotrochus bruuni) live at depths of up to 10,687 meters. In shallower waters, sea cucumbers can form dense populations. The New Zealand strawberry sea cucumber (Squamocnus brevidentis) lives on rocky cliffs along the southern coast of the South Island, where its populations sometimes reach densities of 1000 animals per square meter. For this reason, one such area in Fiordland is called the "strawberry fields".

Movement

Some abyssal species in the abyssal order Elasipodida have evolved "benthopelagic" behavior: their bodies are almost as dense as the water around them, so that they can make long (up to 1000 m) jumps before slowly sinking to the ocean floor. Most of them have specific swimming appendages, such as an umbrella (for example, Enypniastes) or a long projection on the body (Psychropotes). Only one species is known to be a true, completely pelagic species that never approaches the bottom - Pelagothuria natatrix.

Diet

Holothurians are typically scavengers, feeding on debris in the benthic zone of the ocean. Exceptions include some pelagic cucumbers and the species Rynkatorpa pawsoni, which have a symbiotic relationship with deep-sea monkfish. The diet of most sea cucumbers consists of plankton and decaying organic matter found in the sea. Some sea cucumbers catch food that flows near their exposed tentacles. They also sift through sediment using their tentacles. Other species may burrow through the lower mud or sand until they are completely underground. They then extend their feeding tentacles, ready to escape at any sign of danger. In the South Pacific, sea cucumbers can occur at densities of 40 individuals per square meter. These populations can process 19 kilograms of sediment per square meter per year. The shape of the tentacles is usually adapted to the diet and size of the particles consumed: biofilters generally have complex tree-like tentacles designed to maximize the surface area available for filtration, while substrate-feeding species most often require finger-like tentacles for sorting nutritious material; detrital species that live in fine sand or mud most often require shorter, "toothed" tentacles shaped like scoops. One individual can ingest more than 45 kg of sediment per year. The outstanding digestive abilities of sea cucumbers allow them to reject finer, cleaner and more uniform sediment. Therefore, sea cucumbers play an important role in the biological treatment of the seabed (bioturbation, scavenging, substrate homogenization, etc.).

Communication

Sea cucumbers communicate with each other by transmitting hormonal signals through the water. The main purpose of communication is reproduction; otherwise, individuals tend to ignore each other. Sea cucumbers do not exhibit territorialism. Some species, including abyssal species such as porpoises (Scotoplanes globosa), can live in groups.

Reproduction

Most sea cucumbers reproduce by releasing sperm and eggs into the ocean water. Depending on conditions, a single organism can produce thousands of gametes. Sea cucumbers are generally dioecious, with separate male and female organisms, but some species are protandrous. The reproductive system consists of a single gonad, consisting of a cluster of tubules flowing into a single canal that opens on the upper surface of the animal, next to the tentacles. At least 30 species, including Pseudocnella insolens, fertilize their eggs internally and then pick up the fertilized zygote with one of their tentacles. The egg is then inserted into a pouch on the adult's body, where the fetus develops and eventually hatches from the pouch. Several species are known to breed in body cavities and give birth through a small tear in the body wall, near the anus.

Development

In all other species, the egg develops into a larva, which is free-swimming, usually after about three days of development. The first stage of larval development is known as auricularia (the larva is about 1 mm long). Such a larva swims with the help of a long strip of cilia wrapped around its body, and somewhat resembles a bipinnaria (starfish larva). As the larva grows, it develops into a doliolaria with a barrel-shaped body and three to five individual rings of cilia. "Pentacular" is the third larval stage of the sea cucumber, in which the tentacles appear. The tentacles are usually the first features of the adult to appear before the normal tube legs.

Symbiosis and commensalism

Predators and defense mechanisms

Marine predators often refuse to eat sea cucumbers due to the toxins they contain (particularly holothurin) and their impressive defense mechanisms. However, they remain prey for some highly specialized predators that are unaffected by their toxins, such as the large clams Tonna galea and Tonna perdix, which paralyze the sea cucumbers using a powerful venom before swallowing them completely. Some other, less specialized and opportunistic predators may also prey on sea cucumbers if they cannot find more suitable food, such as certain types of fish (triggerfish, puffer fish) and crustaceans (crabs, lobsters, hermit crabs). Some species of coral sea cucumbers in the order Aspidochirotida can defend themselves by expelling their sticky Cuvier tubes (extensions of aquatic lungs that float freely in the coelom) to entangle potential predators. When sea cucumbers are startled, they may expel some tubes through a tear in the cloaca wall in an autonomous process known as emptying. Replacement tubes grow within one and a half to five weeks, depending on the type. The release of these tubes can also be accompanied by the release of a toxic chemical known as holothurin, which has properties similar to soap. This chemical substance can kill animals in the surrounding area and is another method of protecting sea cucumbers.

Aestivation

If water temperatures become too warm, some species of sea cucumber from temperate seas may go into summer hibernation. While they are in this state of rest, they stop feeding, their intestines atrophy, their metabolism slows, and they lose weight. The body returns to its normal state when conditions improve.

Phylogeny and classification

Holothurians do not have a skeleton like other echinoderms and their classification is more complex, with their paleontological phylogeny relying on a number of well-preserved specimens. Modern taxonomy is based primarily on the presence or shape of certain soft parts (legs, lungs, tentacles) to determine the major orders and, secondly, on microscopic examination of the ossicles to determine the genus and species. Modern genetic methods have greatly contributed to the development of the classification of these animals. Taxonomic classification, in accordance with the World Register of Marine Species:

Squad Apodida (Brandt, 1835)

Family Chiridotidae (Östergren, 1898)

Family Myriotrochidae (Théel, 1877)

Family Synaptidae (Burmeister, 1837)

Squad Aspidochirotida (Grube, 1840)

Family Holothuriidae (Burmeister, 1837)

Family Mesothuriidae (Smirnov, 2012)

Family Stichopodidae (Haeckel, 1896)

Family Synallactidae (Ludwig, 1894)

Squad Dendrochirotida (Grube, 1840)

Family Cucumariidae (Ludwig, 1894)

Family Cucumellidae (Thandar and Arumugam, 2011)

Family Heterothyonidae (Pawson, 1970)

Family Paracucumidae (Pawson and Fell, 1965)

Family Phyllophoridae (Östergren, 1907)

Family Placothuriidae (Pawson & Fell, 1965)

Family Psolidae (Burmeister, 1837)

Family Rhopalodinidae (Théel, 1886)

Family Sclerodactylidae (Panning, 1949)

Family Vaneyellidae (Pawson and Fell, 1965)

Family Ypsilothuriidae (Heding, 1942)

Squad Elasipodida (Théel, 1882)

Family Deimatidae (Théel, 1882)

Family Elpidiidae (Théel, 1882)

Family Laetmogonidae (Ekman, 1926)

Family Pelagothuriidae (Ludwig, 1893)

Family Psychropotidae (Théel, 1882)

Squad Molpadida (Haeckel, 1896)

Family Caudinidae (Heding, 1931)

Family Eupyrgidae (Semper, 1867)

Family Gephyrothuriidae (Koehler & Vaney, 1905)

Family Molpadiidae (Müller, 1850)

Holothurians: use in cooking and medicine

To supply market demand in Southern China, Makassar sea cucumber fishermen trade with indigenous Australians from Arnhem Land. This is the first recorded example of trade between the inhabitants of the Australian continent and their Asian neighbors. There are many commercially important species of sea cucumber that are harvested and dried for export for use in Chinese cuisine. Some of the most commonly found types in markets include:

Holothuria nobilis

Thelenota pineapples

Actinopyga echinites

Actinopyga palauensis

Holothuria scabra

Holothuria fuscogilva

Actinopyga mauritian

Stichius japonicus

Apostichopus californicus

Acaudina molpadioides

Isostichopus fuscus

Sea cucumber as a food product

Sea cucumbers are marine animals of the class Holothuroidea. They are used in fresh or dried form in various cuisines around the world. In some cultural contexts, sea cucumber is believed to have medicinal value. The animal itself and food product usually called bêche-de-mer in French, from the Portuguese "bicho do mar" (literally " sea worm"), trepang (or tripang) in Indonesian, namako in Japanese, balatan in Tagalog and loli in Hawaiian Islands. In Malay, sea cucumber is known as gamat. In most cultures in Eastern and Southeast Asia, sea cucumbers are considered a delicacy. Sea cucumber is used in a number of dishes. Common ingredients used in sea cucumber dishes include wax melon, dried scallop, kai-lan, shiitake, and bok choy.

Culinary use

Fresh and dried forms of sea cucumber are used in cooking, although preparation is difficult due to the fact that it is completely tasteless. The Suiyuan shidan, a Qing Dynasty Chinese guide to gastronomy, states: “As an ingredient, sea cucumbers have little taste, are full of sand and have a strong fishy smell. For these reasons, they are difficult to cook tasty.” Most of the preparation of a sea cucumber for consumption involves peeling and boiling it, then simmering it in meat broths and extracts to add flavor to each sea cucumber. According to Chinese popular belief, sea cucumber has a positive effect on male sexual health and is an aphrodisiac, as it physically resembles a phallus and uses defense mechanism, similar to ejaculation, because in case of danger it freezes and pushes a stream of water towards the aggressor. Sea cucumber is also believed to protect against tendinitis and arthritis.

Commercial fee

IN recent years, the sea cucumber industry in Alaska has increased due to increased exports of sea cucumber skin and muscle to China. In China, sea cucumbers are sold commercially in artificial ponds. These ponds can reach an area of 400 hectares and satisfy most of the local demand. Wild sea cucumbers are collected by divers and these wild Alaskan sea cucumbers have higher nutritional value and larger size than farmed Chinese sea cucumbers. Larger sizes and taller nutritional value allowed Alaskan fisheries to continue to compete for market share despite increased cultivation of local, Chinese sea cucumber. One of Australia's oldest fisheries is the collection of sea cucumbers by divers from around the Coral Sea ( Pacific Ocean, off the coasts of Australia, New Guinea and New Caledonia) in far North Queensland, Torres Strait and Western Australia. In the late 1800s, 400 divers were deployed to collect sea cucumbers in Cooktown, Queensland. Overharvesting of sea cucumbers in the Great Barrier Reef threatens their population. Their popularity as a delicacy in Asian countries poses a serious threat to the order Aspidochirotida.

Holothuria is an unusual animal that visually resembles a plant. This animal belongs to the class of invertebrates, the type of echinoderm. These “sea sausages”, which is exactly what they look like, have many names - sea cucumber, sea cucumber, sea ginseng.

Class Holothuria unites many species, namely 1150. Each species differs from other representatives of this class in a number of characteristics. Therefore everything holothurian species were combined into 6 types. The criteria that were taken into account during separation were the following: anatomical, external and genetic features. So, let's get acquainted with the types of sea cucumbers:

1. Legless holothurians do not have ambulacral legs. Unlike their other relatives, they perfectly tolerate desalination of water, which has affected their habitat. A large number of legless ones can be found in the mangrove swamps of the Ras Mohamed Nature Reserve.

2. Side-footed holothurians are equipped with ambulacral legs on the sides. They prefer life at great depths.

3. Barrel-shaped holothurians. The shape of their body is spindle-shaped. Such type of sea cucumber adapted to life in the soil.

4. Tree-tentacled holothurians are the most common. The most primitive sea cucumbers belong to this type.

5. Thyroid-tentacles have short tentacles that do not hide inside the body.

6. Dactylochirotids unite sea cucumbers that have from 8 to 30 tentacles.

Holothuria maritime, due to its diversity and ability to adapt to any living conditions, is found in almost all seas. The only exceptions are the Caspian and Baltic Sea.

The ocean spaces are also perfect for their living. Largest accumulation holothurian sea cucumber in tropical and subtropical waters. These cucumbers can settle both in shallow water and in deep-sea depressions. Their main refuge is coral reefs and rocky soils overgrown with vegetation.

The body of these underwater inhabitants is oblong, which is probably why they are called sea cucumbers. The skin is rough and wrinkled. All muscles are quite developed. At one end of the body there is a mouth, and at the other an anus. There are tentacles around the mouth.

With their help, sea ginseng captures food and sends it into the mouth. They swallow food completely, since they have no teeth. Nature did not endow these monsters with a brain, and the nervous system consists of only a few nerves connected in a bundle.

Holothuria sea cucumber

Distinctive feature sea cucumber sea ginseng is their hydraulic system. The water lungs of these extraordinary animals open in front of the anus into the cloaca, which is completely unusual for other living organisms.

The color of these animals is quite bright. They come in black, red, blue and green. Skin color depends on where holothurian lives. Their color most often harmoniously combines with the colors of the underwater landscape. The sizes of such “underwater worms” have no clear boundaries. They can be from 5 mm to 5 m.

Character and lifestyle of sea cucumbers

Lifestyle of sea cucumbers- inactive. They are in no hurry and crawl slower than turtles. They move along the seabed on their sides, since this is where their legs are located.

Pictured is sea cucumber sea ginseng

You can see such an unusual way of transportation at photo of sea cucumber. During such walks, they use their tentacles to capture edible particles of organic matter from the bottom.

They feel great at great depths. So, at a depth of 8 km, sea ginseng considers itself a full-fledged owner, and this is not accidental. They make up 90% of all bottom dwellers at great depths.

But even these “bottom masters” have their enemies. Holothurians have to defend themselves from starfish, crustaceans and some species. To protect themselves, sea cucumbers use “special weapons.” In case of danger, they can shrink and throw their internal organs into the water.

As a rule, these are the intestines and genitals. Thus, the enemy is lost or feasts on this “dropped ballast”, and in the meantime the front part of the cucumber escapes from the battlefield. All missing body parts are restored in 1.5-5 weeks and the sea cucumber continues to live as before.

Some species defend themselves slightly differently. During skirmishes with the enemy, they produce toxic enzymes that are deadly poison for many fish.

This substance is not dangerous for people, the main thing is that it does not get into your eyes. People have adapted to use this substance for their own purposes: for fishing and scaring.

In addition to enemies, sea ginseng also has friends. About 27 species of the carp family use sea cucumbers as a home. They live inside these unusual animals, using them as shelter in case of danger.

Sometimes these “cucumber fish” eat the reproductive and respiratory organs of sea cucumbers, but due to their restorative ability, this does not cause much harm to the “hosts”.

Holothuria edible not only underwater inhabitants, but also people believe. Sea cucumbers are used to prepare delicacies, as well as in pharmacology. They are tasteless, but very healthy.

Interesting fact is that when you get a sea cucumber to the surface, you must sprinkle it with salt so that it becomes hard. Otherwise, upon contact with air, the mollusk will soften and resemble jelly.

Holothurian nutrition

Sea cucumbers are considered the orderlies of the ocean and seas. They feed remnants of the dead animals. Their mouth end is always raised in order to catch food with the help of tentacles.

Number of tentacles different types not the same. Their maximum number is 30 pieces, and they are all in constant search for food. The holothurian licks each of the tentacles in turn.

Some species feed on algae, others on organic debris and small animals. They are like vacuum cleaners, collecting food mixed with silt and sand from the bottom. The intestines of these animals are adapted to select only nutrients, and send everything unnecessary back out.

Reproduction and lifespan of holothurians

Holothurians have 2 methods of reproduction: sexual and asexual. During sexual reproduction, the female releases eggs into the water. Here, outside, fertilization of the eggs occurs.

After a while, larvae will emerge from the eggs. In their development, these babies go through 3 stages: dipleurula, auricularia and doliolaria. In the first month of their life, the larvae feed exclusively on unicellular algae.

The second option for reproduction is self-reproduction. In this case, holothurians, like plants, are divided into several parts. Over time, new individuals grow from these parts. These extraordinary creatures can live from 5 to 10 years.

Or caterpillars. They are capable of shrinking strongly even with a slight touch, which is why they are sometimes associated with egg pods.

Sea cucumber - echinoderm an invertebrate mollusk with more than a thousand species. The varieties of these marine inhabitants differ in size, tentacles, and the structure of some organs.

They have a wrinkled, leathery body that resembles a cucumber due to its oval shape. On thick skin, growths resembling thorns are noticeable. On one side of its body there is a mouth surrounded by tentacles, on the other there is an anus. Sea cucumbers can be of very different colors - black, brown, green, gray, red.

Sea cucumbers also differ in size - some species look like dwarfs and reach sizes from several millimeters to several centimeters, other varieties can reach a length of up to two and even five meters. Miners hunt such giants with particular enthusiasm. Sea urchins and starfish are closest to sea cucumbers.

Pictured is a sea cucumber

The most ancient sea cucumbers were known already in the Silurian period; the name “sea cucumber” itself belongs to the Roman philosopher Pliny, and Aristotle created the first descriptions of some species.

About a hundred species of these mollusks live in Russia, the most popular is the Japanese variety sea cucumber – cucumaria. This type of sea cucumber is different useful composition and excellent taste, and are often used in cooking. Sea cucumbers are the species of sea cucumbers that can be eaten.

Sea cucumber lifestyle and habitat

Sea cucumbers found in different parts of the ocean, both in shallow waters near the shore, and in deep-sea depressions, and in coral reefs, in tropical latitudes. They are common in sea depths almost all over the world.

Holothurians are slow and lazy, they crawl along the bottom, and this makes them easy prey for hunters. Most of the time they lie at the bottom, “on their side.” Deep-sea species may have elongated ambulacral legs that serve as animal stilts and help move along the bottom and rocks.

The muscles of echinoderms are developed enough to move along the bottom and contract sharply in case of danger. Some species are able to attach themselves to rocks or burrow into mud. Holothurians themselves can become prey for starfish, fish, crustaceans or gastropods.

Similarly, in the event of an attack or other danger, sea cucumbers “explode” - scattering their body into pieces. While the opponent chooses a tastier piece, at this time the front part of the cucumber is saved.

In case of danger, the sea cucumber can throw back part of its intestine to create a diversionary maneuver.

The body of echinoderm mollusks subsequently quickly regenerates. Sea cucumbers are animals, which can regenerate if half of the body is preserved, they can even recover from a quarter of their body. The regeneration process can take from one and a half to five weeks.

Sea cucumber nutrition

How do sea cucumbers hunt? All types of sea cucumbers have special tentacles located around the mouth. The number of tentacles can vary from 8 to 30.

The tentacles are usually short, designed to collect nutrients from the ground surface. Holothurians also have branched tentacles that can cover a large area of water in order to catch prey.

Their diet consists of plankton, plants, small animals and organic matter that can be extracted from bottom sand or silt. They are sometimes called marine orderlies because they clean the bottom surface of the remains of dead animals, using these organic substances as a nutrient.

American scientists carefully studied the features of the nutritional system of sea cucumbers. They discovered that holothurians feed primarily through the mouth, but the anus can also perform food capture functions, which in these simple invertebrates is also involved in respiratory system. The respiratory functions of these invertebrates are also performed by water lungs.

In Russia, cucumaria and other types of sea cucumbers are common on Sakhalin, Primorye, as well as in the Seas of Okhotsk, Japan and Barents, at a depth of half a meter to one hundred meters.

Sea cucumber reproduction and lifespan

Holothurians are hermaphrodites; they produce male and female reproductive cells alternately, sometimes even simultaneously. They reproduce by spawning; they have bright green eggs; the eggs hatch into larvae that can swim.

Spawning often occurs in the evening or at night; darkness may be important. Cucumaria spawns twice, in May and July. Holothurians living in Atlantic Ocean, spawn off the coast of Sweden in the fall, from October to December. Some species can spawn year-round. The larvae swim in plankton for about two weeks, then sink to the bottom.

The sea cucumber uses its tentacles to collect food from the bottom.

About 30 species of sea cucumbers are sexual and are divided into males and females. They care for the young and carry the young on the surface of the mother's body.

Rare cases of reproduction by division have also been recorded and described by scientists: half of the body is able to recover to its full volume. Holothurians live quite a long time, from five to ten years.

Due to the great popularity of cucumaria and its demand as a culinary product, as well as in pharmacology, artificial breeding of sea cucumbers is practiced, including in Russia and the Far East.

About useful properties of sea cucumber It was also known in ancient Eastern medicine; it has long been called sea ginseng. Cucumaria meat is practically sterile, not susceptible to viruses and bacteria, these mollusks are unusually rich useful substances, microelements, especially iodine, as well as fluorine, calcium, amino acids and others.

Sea cucumbers are very low in calories, so their products can form the basis of a diet for those who want to lose weight. This product is used as a healing agent that stimulates the body's defenses for people suffering from increased fatigue and loss of strength. Sea cucumbers help a person quickly regain strength after surgery or a long illness.

Sea cucumber meat is beneficial for health, it normalizes metabolism, stimulates the heart, can help lower blood pressure, promotes rapid tissue regeneration, which is why it is used during operations.

Sea cucumbers have a healing effect on joints and help with arthritis. Sea cucumbers are also used to produce food additives and pharmaceuticals.

You can buy sea cucumber not only for the sake of useful and medicinal properties- Delicious dishes are prepared from them. Sea cucumbers make excellent salads, invertebrate mollusks, after peeling, frying and stewing, and can also be preserved. Some types of sea cucumber are considered delicacies and attract a lot of attention from gourmets.