The largest sea star. The world's largest starfish. Do these beautiful underwater creatures have enemies

Mysterious animal - starfish. First, STAR. Where else can you find such a natural configuration. Secondly, for some reason it initially seemed to me that it was some kind of algae or coral. Look at the variety and beauty of these stars! However, watch further video about how they eat 🙂

(Total 28 photos)

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1. Starfish are veterans of the seabed, they appeared more than 450 million years ago, ahead of many forms of modern inhabitants of the underwater depths.

2. They belong to the class Echinoderms, being relatives of sea cucumbers, brittle stars, sea lilies, holothurians, sea urchins - at present there are about 1600 species of them, having a star-shaped or pentagonal shape.

4. In a starfish, despite its inactivity and lack of a head as such, the nervous and digestive systems are well developed. And why, in fact, "echinoderms"? It's all about the hard skin of the starfish - on the outside it is covered with short needles or spikes. Conventionally, these bizarre creatures can be divided into three groups: ordinary starfish; feather stars, named for their writhing rays (up to 50!), and "fragile" stars that cast their rays in case of danger.

5. True, it will not be difficult for this animal to grow new ones for itself, and new stars will soon appear from each beam. How is this possible? - Thanks to characteristic feature structure of a star - each of its rays is arranged in the same way, and contains: two digestive outgrowths of the stomach that perform the function of the liver a red eye spot at the tip of the ray, protected by a ring of needles on the ventral side of the papule - skin gills in the form of thin short villi located on the back and producing gas exchange processes of the genital organs (usually two gonads on each ray) a skeleton consisting of a longitudinal row of vertebrae inside, and hundreds of calcareous plates with spikes covering the skin and connected muscles, which not only protects the animal from damage, but also makes its rays very flexible. The bodies of starfish are 80% calcium carbonate.

6. Thus, each ray of a starfish, once separated from its body, is quite viable and quickly regenerates. Well, connected together, the rays form closed systems in the center of the animal: the digestive system passes into the stomach from two sections and opens with a button-shaped disc that functions as a mouth; bundles of nerves are combined into a nerve ring. The main system of the starfish, which we deliberately left "for dessert" - ambulacral. This is the name of the water-vascular system, which serves as an echinoderm simultaneously for breathing, excretion, touch and movement, together with the muscles providing the musculoskeletal function. Channels extend from the perioral ring into each ray, from which, in turn, lateral branches lead to hundreds of cylindrical tubes on the surface of the body - ambulacral legs, containing special ampoules and ending with suckers. An opening on the back, called the mandreopor plate, serves to connect this system to the external aquatic environment.

7. So how does the ambulacral system work? - It is filled with water under slight pressure, which, getting through the mandreopor plate into the near-oral canal, is divided into five channels of rays and fills the ampoules at the base of the legs. Their compression, in turn, fills the legs with water and stretches them. In this case, the suction cups of the legs are attached to various subjects seabed - and then sharply reduced - the ambulacral legs are shortened, and thus the body of the animal moves in smooth jerks.

8. Starfish are voracious predators, although there are exceptions in the form of herbivorous species that feed on algae and plankton. In general, the favorite delicacies of these animals are clams, mussels, oysters, scallops, littorins, sea ducks, reef-building corals and various invertebrates. The star finds its prey by smell. Having found a mollusk, it sticks with two rays to one shell valve, the remaining three - to the other valve - and a many-hour struggle begins, which the starfish always wins. When the mollusk gets tired, and the doors of its dwelling become pliable, the predator opens them and literally throws its stomach on the victim, turning it out! By the way, the digestion of food takes place outside the body of the animal. Some starfish are even capable of digging up prey hiding in the sand.

9. As for reproduction, for the most part, starfish are divided into males and females. Fertilization occurs in water, after which free-swimming larvae are formed, called brachiolaria. Unlike adults, their structure is subject to the laws of symmetry, and includes a ciliary cord necessary for collecting food particles (exclusively unicellular planktonic algae), a stomach, esophagus and hindgut. Usually, the larvae swim near an adult starfish of the same species - and after several weeks, under the influence of its pheromones, metamorphosis takes place with them: having fixed on the bottom, they turn into tiny (0.5 mm in diameter), but already five-link starfish. And these kids will be able to give offspring only after two or three years. If the larvae perform the function of dispersal of the species, and drift over long distances, they are able to delay their transformation into adults and not settle to the bottom for several months - while they can grow up to nine cm in length. There are also hermaphrodites among starfish - they bear their young in a special hatching bag or cavities on their backs.

10. Taking into account the large number of starfish, it is clear that they also affect the growth of populations of the species that are hunted. Nobody risks hunting them, since their bodies contain extremely poisonous substances - asteriosaponins. Being practically invulnerable, starfish are at the top of the marine food pyramid, and therefore their life expectancy can reach 30 years. According to scientists, these brightly colored legendary inhabitants of the seas also make a significant contribution to the process of utilization of carbon dioxide produced, among other things, by industrial facilities on the planet - their share is about 2% CO2, that is, more than 0.1 gigatons of carbon per year , which for such seemingly small creatures, you see, is not at all weak!

One of the most beautiful animals not found on land is starfish. Divers diving in warm seas often manage to admire these unusual and interesting creatures.

Echinodermata (Echinodermata), which include starfish, are an independent and very peculiar type of animal world. According to the structure of the body, they are completely different from other animals and, thanks to the peculiarities of organization and original form bodies have long attracted attention.

Echinoderms appeared on Earth a very long time ago, more than 500 million years ago. The presence of a calcareous skeleton contributed to good preservation fossil remains of the ancestors of these creatures.
In the glorious and numerous community of echinoderms, the class of starfish (Asteroidea) is represented by a huge variety of species, differing from each other in size, body shape and some differences in organization.

And at the end of the post you can watch an interesting video in my opinion how the stars hang out and how they eat.

In the fossil state, they have been known since the Lower Paleozoic - from the Ordovician period, i.e. about 400 million years ago. There are currently over 1500 known modern species sea ​​stars, which are systematized in about 300 genera and 30 families. Opinions often differ between scientists about the number of starfish orders. Previously, they were combined into three orders - clearly lamellar, needle and pedicellarian stars. Currently, they are already divided into 5-9 different units in various sources. I think that for us it is not very important.

Sea stars are exclusively marine animals, they are not found in fresh water. They do not live in heavily desalinated seas, for example, in the Azov or Caspian, although sometimes they can be represented by single oppressed species. So, for example, individuals of A. rubens stars are sometimes found in the western part of the Baltic Sea (near the island of Rügen), but here they do not breed, and the population of these starfish is supported by larvae introduced by currents. And the only starfish that penetrated from the Mediterranean into the Black Sea - Marthasterias glacialis - lives only in its most salty part - in the area of ​​the Bosphorus.

In the seas and oceans with normal salinity, starfish are found everywhere - from the Arctic to the Antarctic, and are especially numerous in the warm waters of the seas. The deep range of habitation of sea stars is also wide - from the surface layers of the sea to kilometer depths, although, of course, at great depths species diversity and the number of starfish is more meager.
About 150 species of starfish live in the Russian seas, which live, with very rare exceptions, in the northern and Far Eastern seas.

All starfish in adulthood lead a bottom lifestyle, crawling along the bottom surface or burrowing into the ground. Many of the starfish, especially those living in shallow coastal waters, are active predators that feed on various small benthic organisms - mollusks, crustaceans, other invertebrates, including echinoderms, and even fish. Do not disdain carrion.
Among the deep-sea starfish, hoary-eaters predominate - they use sea soil for food, extracting organic matter from it. Some starfish can feed on plankton.

Usually, starfish are not very picky about food and will gobble up everything they can. The diet of, for example, the Chilean starfish Meyenaster includes up to 40 species of echinoderms and molluscs.
Most starfish detect and locate their prey through substances that the prey releases into the water. Some soft-bottom starfish, including species of the genera Luidia and Astropecten, are able to find burrowed prey and then excavate the substrate to reach their prey. Stylasterias forreri and Astrometis sertulifera from the west coast of the United States of America, as well as Leptasterias tenera from the east coast, grab small fish, amphipods and crabs with pedicellaria when the prey stops over or near a starfish.

Interesting way to use starfish many species of bivalve molluscs as food. The star crawls onto the body of such a prey and attaches to it with its legs on the rays, giving some effort towards opening the valves of the mollusk shell. Gradually, the muscles of the mollusc that hold the shell valves in the closed state get tired and slightly open the shell. The starfish turns its stomach inside out and squeezes it into the gap between the valves, starting the meal right inside the clam shell. Food is digested in this way in a few hours.

The inside-out stomach is a unique feeding organ for many starfish. The starfish Patiria miniata from the west coast of America, for example, spreads its stomach along the bottom, digesting organic matter that comes across.

Sea stars usually have a more or less flattened body with a central disk gradually turning into rays radiating from it. The mouth opening is located on the underside (oral) side of the disk of the starfish. Most stars have an anus on the upper body, in some species it is absent altogether. In the middle of the lower side of each beam there is a groove, in which there are many soft and mobile outgrowths - ambulacral legs, with the help of which the starfish moves along the bottom. Typical for starfish is a five-ray structure, but there are stars with 6 or more rays. For example, the solar starfish Heliaster has 50 rays.

Sometimes the number of rays varies even among individuals of the same species. So, in the starfish Crossaster papposus, which is common in our northern and Far Eastern seas, the number of rays ranges from 8 to 16.
The ratio of the length of the rays and the diameter of the disk also varies. In some deep-sea starfish, the length of the rays is 20-30 times the diameter of the disk, while at the same time, in the common Patiria star (Patiria pectinifera) in the Sea of ​​​​Japan, the rays only slightly protrude beyond the disk, which is why the star has the shape of a regular pentagon . These stars are also called biscuit stars for their similarity to flat cookies.

Even sea stars are known, whose appearance is so changed that it is difficult to recognize them as a star. A common inhabitant of coral reefs, the New Guinean cultite (Culcita novaeguineae), has a strongly swollen body, resembling a strongly swollen pillow or roll in shape. However, this body shape is only in adult stars - young culcites have the shape of regular pentagons.
Typically, sea stars that live at shallow depths have a very diverse coloration of the upper body. There may be a variety of colors and shades of the spectrum. Sometimes the coloring is spotty and form a bizarre pattern. The ventral side of the body of starfish has a more modest color, usually it is pale yellow.

The color of stars living at great depths is also paler - usually dirty gray or with shades gray flowers. Some (eg Brisinga) have the ability to glow.
The variety of color of starfish depends on the pigment inclusions located in the cells of the skin epithelium.
Dimensions various kinds starfish can vary from a few centimeters to 1 meter. Most often, divers meet starfish 10-15 cm in size.
The lifespan of some starfish species can be over 30 years.
The sensory organs of the starfish are poorly developed and are represented by red eye spots located at the tips of the rays and tactile receptors located on the skin.

When you first look at a starfish, you first of all notice the numerous elements of the calcareous skeleton located on the surface of the body - plates, needles, spikes, tubercles, etc. But in fact, the skeleton of starfish is not external, like in mollusks or arthropods, but is located under the skin epithelium, sometimes very thin. The calcareous plates of starfish do not form a single integral skeleton, but are attached to each other with the help of connective tissue and muscles. Starfish have a basic skeleton called a supporting skeleton and various appendages to it - spikes, tubercles and outgrowths that have a protective function. Sometimes such spines and bristles form a continuous cover on the upper side of the body of starfish.

Reproduction of starfish can take place in several scenarios. If a starfish with a part of the disk is torn off, then two individuals are formed from the resulting pieces of the star. The time for such regeneration can be up to 1 year. Some starfish reproduce in a similar regenerative way. In their body, softening of the connective tissue occurs and they break up into several parts, more often into two. Soon independent starfish will grow from these parts. Species of the genus of sea stars Linkia (Linckia), common in the Pacific Ocean and other regions of the World Ocean, are unique in their ability to cast rays as a whole. From each such ray, if it is not eaten by a predator, a new starfish can be regenerated. Such reproduction is called asexual.

Sea stars also reproduce sexually. Most types of stars are dioecious, i.e. represented by males and females. Reproduction is carried out by fertilization of the female eggs with the reproductive products of males, which are hatched directly into sea ​​water. A female starfish can release several million eggs at a time.
Among the stars there are also unisexual (hermaphroidal) species. These species include, for example, the common European starfish Asterina gibbosa, which is a hermaphrodite. In such stars, both female and male reproductive products are produced in the body. Juveniles they usually bear in a special hatching bag or cavities on the back.
The larvae that hatch from the eggs usually feed on plankton and, growing up, sink to the bottom, moving on to the usual way of life for sea stars.

Starfish have no natural enemies. These animals contain toxic substances in their bodies - asteriosaponins, so predators do not honor them with attention. In addition, there are few nutrients in the body of the starfish and they do not represent a high-calorie food.

crown of thorns

On the coral reefs of the Pacific and Indian Oceans, a large starfish crown of thorns or acanthaster (Acanthaster plansi) is often found, reaching a diameter of 50 cm and belonging to the genus Acanthasteridae.
It is generally accepted that starfish are completely harmless to humans, but careless handling of the crown of thorns can lead to serious trouble. The starfish crown of thorns is notorious among the inhabitants of many tropical islands. It is impossible to pick it up without getting the burning pain of the pricks of the numerous needles that cover the body of the starfish.
The crown of thorns gives a lot of trouble to pearl divers - if a swimmer accidentally steps on the body of an acanthaster, then its needles pierce the foot and break off in the human body, infecting the blood with poisonous secretions

Local residents believe that the victim should immediately turn the crown of thorns upside down with a stick and put his foot to his mouth. It is believed that the star sucks out the fragments of its needles from the human body, after which the wounds heal quickly.

The crown of thorns, or acanthaster, is known for another unpleasant property. He is extremely fond of eating coral polyps, thereby destroying the reef itself and leaving its inhabitants without food and shelter. IN different years there have been outbreaks of significant increases in the abundance of these starfish in some regions. Then the very existence of the reefs and their inhabitants was threatened.

Significant human resources were thrown into the fight against crowns of thorns. The stars were collected in baskets and destroyed, but this did not give a tangible effect. Fortunately, crown-of-thorns outbreaks soon stopped and the coral reefs did not die completely.
Some starfish cause damage by destroying fishing grounds and plantations of oysters and mussels. Such pests are collected with special gear from the fishing areas and destroyed.

It should also be noted the useful role that starfish play in the ecology of the oceans, and the planet as a whole. These creatures intensively absorb and utilize carbon dioxide, which is becoming more and more in the Earth's atmosphere every year. Every year, starfish utilize up to 2% of atmospheric carbon dioxide. This is a very big number.
In addition, starfish are the orderlies of the seabed, eating carrion and the remains of dead marine organisms, as well as weaker and sicker individuals of marine animals.

Interesting Facts:

The largest of the 1600 varieties of starfish in terms of the total span of tentacles is considered to be very fragile midgardia xandaros. In the summer of 1968, a representative of this species was caught in the southern part of the Gulf of Mexico by the research vessel "Adaminos" of the University of Texas. Its length, together with tentacles, was 1380 mm, but the diameter of its body without tentacles reached only 26 mm. When dried, it weighed 70 g.
It is believed that the five-pointed star has the maximum weight of all starfish. Thromidia catalai living in the western part of the Pacific Ocean. A representative of this species, caught on September 14, 1969 in the Ailot Amedi region in New Caledonia and later exhibited in the Noumea aquarium, weighed 6 kg, and its tentacle span reached 630 mm
The smallest known was the starfish asterenids ( Patmella parvivipara), discovered by Wolf Seidler on the west coast of the Eyre Peninsula, South Australia, in 1975. It had a maximum radius of 4.7 mm and a diameter of less than 9 mm.
The crown of thorns is considered the most predatory starfish in the world ( Acanthaster planci), living in the basins of the Pacific and Indian oceans, as well as in the Red Sea. It has the ability to destroy up to 300-400 square centimeters of coral per day.
The maximum depth at which a marine avead can be found is considered to be a depth of 7584 m. At this depth, the Soviet research vessel Vityaz discovered a specimen Porcellanaster Ivanovi.

The starfish has small patches at the tip of each ray of the star that act as light sensors and contain a red pigment that changes color. It is assumed that these areas (front sights) affect the movement of the starfish.

The starfish can feed without swallowing food. For example, when she meets a bivalve mollusk, she wraps her arms around it and turns the lower stomach inside out. It penetrates the shell, envelops the soft parts of the mollusk and digests it, and then the starfish simply draws in the diluted solution. Spiders act in a similar way - however, they do not know how to twist the stomach, but simply inject digestive juice into the victim.

Sea stars

classis Asteroidea de Blainville, 1830

These echinoderms usually have a flattened body that smoothly transitions into radial "arms" (5-40) called rays. The shape and structural features of the rays are very diverse: from wide and short, giving the animal pentagonal contours, to thin and long, resembling tentacles. Unlike lilies, the mouth of movie stars and ambulacral furrows are located on the lower surface of the body facing the substrate.


In those situations where movie stars have an anus, it, like the madrepore plate of the ambulacral system, is located on the upper (dorsal) surface of the body.
All stars are mobile organisms moving along the substrate with the help of ambulacral legs located in ambulacral furrows. Like lilies, movie stars do not have a pronounced anterior-posterior axis and lack any “head end”. Stars are perfect radial animals.
The skeletal plates and spines of movie stars are very diverse, sometimes transforming into special surface organs - pedicillaria. Under a microscope, it is possible to see that pedicellaria is a group of a number of elongated “bones” that work like scissors or tongs. With these tweezers, stars can clean the surface of the body from various fouling organisms that constantly want to settle on these convenient “hosts”.
Most of the movie stars are predators and corpse eaters; stars are known to be detritophages and filter feeders. Often and cannibalism. When capturing a large prey, the star's stomach is able to turn outward from the mouth opening and embrace the prey.
Movie star larvae are called bipinnaria and brachiolaria, but there are also stars with direct development that are able to bear their young and take care of their offspring. Larvae that are able to feed during their own development in plankton are called planktotrophic, and larvae that do not feed on planktonic are called lecithotrophic larvae.
Now about 1500 species of sea movie stars are known, most of which are inhabitants of tropical seas.
In the waters of South Primorye, according to our data, there are 25 species of movie stars. Let's talk about the most typical and often encountered representatives of this class of echinoderms.

Luidia biceps

Luidia quinaria Martens, 1865 bispinosa Djakonov, 1952

This star has a strongly flattened body with 5 long, narrow, tapering rays. The span of rays of luidia reaches 30 cm. On the surface (dorsal) side, the central disk and rays of luidia are dark brown with a violet tint, sometimes almost black, and the lower (ventral) side and sides of the rays are orange-yellow. Along the edges of the rays on the dorsal side, the upper marginal (marginal) plates are clearly visible. The dorsal surface itself is flat and covered with paxillae resembling squares - groups of small needles sitting on one rod. On the sides of the rays there are large flattened needles and small needles extending from the lower marginal (marginal) plates.
They live on silty, silted or sandy soils at depths from 3 to 100 m. Luidia have planktotrophic larvae.

Patiria scallop

Patiria pectinifera (Mueller et Troschel, 1842)

This star has a wide flattened disk and very short wide rays pointed at the ends. The dorsal side is somewhat convex, and the ventral side is completely flat. Rays are usually 5, although there are 4,6 and even 7-ray patirias. The span of rays of the largest specimens reaches 18 cm. yellow spots on the dorsal side and orange-yellow on the ventral side. The dorsal side of the patiria is covered with plates overlapping each other like tiles, the free edges of which always face the center of the disk. Patiria received its specific name for the scallops of needles located on the ventral side, connected at the base by a soft membrane.
Comb Patiria is a low-boreal subtropical species, found mainly in the regions of Southern Primorye. These stars are very common in the intertidal zone among stones and on rocky ground. On sandy, rocky and silty soils, Patiria are found up to a depth of 40 m. They prefer to settle on coarse sandy areas of the bottom with an admixture of pebbles and large stones with curtains and thickets of zostera and phyllospadex algae. Patiria is a predator that prefers to attack medium-sized mollusks.
In the waters of Southern Primorye, Patiria spawn in the second half of August - early September. The larvae of Patyria are planktotrophic.

Solaster pacificus

Solaster pacificus Djakonov, 1938

These cold-water stars prefer great depths and are found in the Southern Primorye, as a rule, deeper than 60-70 m.
Pacific solasters have a wide, slightly convex disk on the dorsal side, from which 7-8 rays are rounded on the sides and slightly swollen, although other representatives of this kind of stars usually have more than 10 rays. These are large stars with a ray span of up to 30 cm. The central part of the disk and wide stripes along the rays are dark purple in color and stand out sharply against the general orange-red background. The upper (dorsal) surface of the solasters is covered with contiguous bundles of low needles of various sizes, sitting on a common base - paxillae.
The features of reproduction and biology of the Pacific solasters have not been studied enough. The larvae are lecithotrophic.

Henricia Hayashi

Henricia hayashi Djakonov, 1961

The systematics of the genus Henricius is very difficult due to the large number of species and the high species variability of these stars, especially the Pacific representatives, so we do not present a photo of a starfish. For the northwestern part of the Pacific Ocean, 28 species of Henricia were recorded, of which 7 species were recorded for Peter the Great Bay in South Primorye. Henricia live at depths from several tens to several hundred meters.
Henricia are 5-ray, thin stars, with a rough dorsal surface to the touch, characterized by a mesh, looped microrelief on a relatively small central disk and rounded rays. In rare cases, 6-beam stars are found. Lifetime coloring of Henrcius is usually red, red-brick, orange.
We singled out Henria Hayashi as the shallowest species, living only in the Sea of ​​Japan and found in South Primorye at depths of 25 to 45 meters on rocky bottoms, while other coastal Henria usually occur deeper than 40 m. The span of rays of Henria Hayashi is up to 10 cm.
Henricius' biology features are very interesting, namely, the manifestation of concern for offspring. All species of this genus are viviparous and do not have free-swimming planktonic larvae. Before laying eggs, the female attaches her rays to underwater objects and raises the rest of the rays and the central disk, forming a kind of bell. Eggs are laid in this enclosed space, which develop in tangles near the mouth (or even in the mother's mouth) into a lecithotrophic larval stage, and then into a small star. All this time (usually up to 3 weeks) Henricia-mother maintains her posture and does not take food.

Lysastrosoma anthosticta

Lysastrosoma anthosticta Fisher, 1922

This 5-ray star is easily distinguished from all others by the “loose”, soft consistency of the body, devoid of the elasticity characteristic of stars, as seen in the photograph. The softness of the dorsal cover is explained by the fact that the plates of the skeleton of lysastrosomes are located very loosely and do not connect with each other into a single shell. The dorsal surface is uneven and bumpy with thin, sparsely located needles. The upper marginal (marginal) plates are widely spaced and connected by chains of small plates. On the lower marginal (marginal) plates on the sides of the rays there are long needles, dressed in a soft sheath, to which a bundle of cruciform pedicillaria is attached.
The span of rays of lysastrosomes reaches 22 cm. The dorsal side is red or dark crimson with a prominent yellow madrepore plate. The underside (ventral) side is light orange.
This species is very widespread in Southern Primorye, occurring in the littoral zone and at shallow depths at the most different soils: sand, stony placers, silty substrates, among boulders and in kelp beds. Lysastrosomes are predators that attack mollusks, crustaceans and other echinoderms, including sea urchins. The larvae are planktotrophic.

Distolasteria prickly

Distolasterias nipon (Doderlein, 1902)

A very large star with a ray span of up to 45 cm, as seen in the photo, often found in Southern Primorye at depths from 2 to 50 m. Usually 5 long strong rays extend from a small central disk, tapering at the ends. The skeletal plates on the dorsal side are arranged in longitudinal rows, and each of them is armed with a strong conical needle. The upper and lower marginal (marginal) plates also bear long blunt needles. All spines are surrounded by a thick ridge of cruciform pedicillaria.
Distolasteries are very beautiful stars: on the back they are velvety black with large bright yellow needles and an orange madrepore plate, and the ventral side is light yellow. Silty soils are preferred. Predators. Spawning occurs in late May - early July. The larvae are planktotrophic.

Letasteria black (photo)

Lethasterias fusca Djakonov, 1931

This seaside 5-ray star is easily distinguished by the black or almost black color of the central disk and rays from the dorsal side. There are also dark gray letasteria, and on the rays against a dark background there may be yellowish and whitish spots, sometimes located in the form of bands. The span of the rays reaches 23 cm. The rays are blunt at the ends, and along the middle of their dorsal side there is a row of wide spines, on top of which there are small spines.
Letasteria live on rocky reefs, rocky soils at shallow depths (2-50 m). Rarely found on silted sands with an admixture of pebbles and stones. Juveniles are found on the thalli of macrophyte algae. They lead a predatory lifestyle, attacking medium-sized mollusks, and are often found in oyster beds or on mussel jars. The larvae are planktotrophic.

Aphelasterias japonica Bell, 1881

Distinctive feature of this medium-sized seaside star - narrow constrictions, lacing off from the small central disk long, relatively thick, but easily breaking off rays. The span of the rays, and these stars have 5 of them, is up to 24 cm. The plates of the dorsal skeleton and the spines of the afelasteria are arranged in transverse rows - scallops. The dorsal side is bright crimson, often with an admixture of purple hues. The tips of the needles and the ventral side are whitish.
Japanese letasteria are quite common in the littoral in the area of ​​stone reefs and capes, and are also found on rocky soils to depths of 40-50 m. They are less common on silted sand with an admixture of pebbles and stones, on shell rocks. They make seasonal migrations. They lead a predatory lifestyle, attacking mainly medium-sized mollusks. In Southern Primorye, afelasteria spawn in August-September. The larvae are planktotrophic.

evasteria prickly

Evasterias echinosoma Fisher, 1926

Spiny eusteria is the largest starfish not only in Primorye, but also in all the Far Eastern seas of Russia. The span of the rays of these huge stars reaches 80 cm. There are always 5 rays, they are long, thick, with rounded sides, with short strong blunt needles on the dorsal plates. Plates with needles are arranged along the rays in regular longitudinal rows. Around the needles are bundles of cruciform prehensile pedicillaries. It is very easy to verify their presence and grip - put the outer part of your palm on the star and the pedicillaria will instantly capture the hairs on your arm.
The dorsal side is dark red with a crimson hue. It lives at shallow depths (5-100 m), where it is usually confined to sandy soils with an admixture of pebbles and silt. Rarely found on pure silts or stones. A predator capable of coping with almost all mollusks and other echinoderms. The larvae are planktotrophic.

Evasteria reticulata

Evasterias retifera f. tabulata Djakonov, 1938

Reticulated eusteria are smaller representatives of this genus, but they also reach 40 cm in the span of rays. Perhaps these are the most beautiful stars of the Far Eastern seas - turquoise-blue mushroom-shaped needles are located against a crimson background, collected in groups and forming a wide-looped network. The madrepore plate and ventral side are orange. The bizarre and bright patterns on the dorsal surface gave these eusteria the species name - reticulate.
These stars are found from the littoral to small (40 m) depths and are usually confined to sandy soils with an admixture of stones. At low tide, small reticulated evasteria are found among stones and boulders. Predators. The larvae are planktotrophic.

Common Amur Star

Asterias amurensis Lutken, 1871

The most common and frequently encountered starfish in the Southern Primorye. Asteria have a wide central disc, from which 5 wide, flattened, with thin, almost sharp, lateral edges, sharpening at the ends of the rays, the span of which in large forms reaches 30 cm, extend. The ventral side is very flat. Dorsal spines small, usually obtusely conical, solitary. The largest of them are sometimes located along the midline of the beam. The color is very variable, ranging from ocher to dark purple, but yellowish-brown, sometimes pinkish-brown forms predominate. They are found in the littoral to depths of 30-40 m, rare deeper. They prefer sandy and rocky soils. On the littoral come across among the stones and thickets of algae. On large thalli of algae, juveniles of asterii form huge clusters (“kindergartens”), covering the surface of macrophytes with small beads. Large asterii are not uncommon in highly polluted bays, where other types of stars no longer survive.
Amur stars are predators that attack mollusks (scallops, oysters, mussels) and other echinoderms, and carrion eaters. In places of large concentrations, cannibalism is often observed. Sometimes, under water, one can observe peculiar “balls” of many asteria, which have stuck around the victim with inverted stomachs.
Of the features of the biology of asterias, their symbiosis (mutually beneficial cohabitation) with polychaete worms (Arctonoe vittata), living in the ambulacral furrows of the star, is interesting. The worm receives the remains of the predator's food, and, in turn, eats numerous epibionts (foulers) from the surface of the star, acting as a cleaner.
In Southern Primorye, the spawning period of Asteria is extended and usually consists of two stages: June-July and September. Amur asterii form dense spawning clusters. The spawning behavior of these stars is interesting. The females rise above the ground on the rays and their reproductive products accumulate between the rays in the form of small (2-3 cm) orange mounds. Males crawl around spawning females, slightly raising the central part and sweeping their sex products white color. Then the stars of both sexes begin to crawl in the area of ​​spawning grounds, simultaneously mixing the sexual products and protecting them from juvenile fish and various crustaceans. This type of behavior can also be called care for offspring. Asterium larvae are planktotrophic.

And finally, how a starfish walks.

The seabed is a beautiful place. Bright starfish, exquisite brittle stars, thick “sausages” of holothurians move along it, sea lilies sway on the stones, huge needles of sea urchins stick out here and there (do not try to step on it in shallow water!). All these creatures belong to the type of echinoderms (lat. Echinodermata).

Only marine animals belong to this type, the habitat of which has become the bottom of the oceans. Mostly free-living, they can also be attached (for example, sea lilies).

Echinoderms are deuterostomes, like chordates. They began their evolution in unimaginable antiquity, even before the beginning of the Cambrian, and now there are about 4 thousand species. The sizes of echinoderms are scattered in a wide range, from 4-5 millimeters to a meter. According to the type of food, echinoderms are predators and prey on invertebrates.

Structure and organ systems of echinoderms

1. Characteristic for echinoderms ray symmetry(in many cases five-rayed), however, their larvae are bilaterally symmetrical, and this suggests that the radial symmetry of adults was acquired secondarily.

2. body integuments arranged in the following way. Above is ciliated epithelium. Below is the layer connective tissue in which hides calcareous skeleton, generating multiple spikes, needles, outgrowths. under the connective tissue coelom epithelium.

3. In body cavity various organs are located, and for some organs there are special pockets, and some seem to be suspended.

4. Nervous system has the form of three rings with radial nerves. Organsfeelings do not differ in a high level of development, although they are diverse. The organs of touch are Ambulacral legs(a starfish, by the way, can open mollusk shells with these handles). At the end of the rays, starfish have eyes, and in hedgehogs, eyes surround the anus.

5. Musculoskeletal system. Unique ambulacral(water-vascular) system is used, among other things, for movement. How is the system set up? The radial canals exit into an annular canal, from which a shortened rocky canal extends. It passes into a madreporous plate, where water is pumped. Further, water enters the ring, from which it is sent to the rays through radial channels. Through radial channels, water fills small capsules lying in the body cavity. They, in turn, pass into small suction cups on the rays-knives. When the capsules are filled with water, the legs lengthen - this is how the starfish moves.

6. Digestive system. Usually, in echinoderms, the mouth and anus are located on different sides of the body. The starfish has a mouth at the bottom, that is, on the side of the abdomen. It passes into a short esophagus, from which food enters the sac-like stomach. By the way, the star can turn its stomach out through the mouth to capture prey! Five pairs of long hepatic outgrowths are stretched from the stomach to the rays, ending blindly. Digestive juice is secreted from the outgrowths, filling the stomach. Undigested food fragments enter the hindgut and are excreted into external environment through the anus on the back. Note that in some species of starfish, the stomach is blind-closed, so that the remnants of food are thrown back through the mouth.

7. Circulatory system open, echinoderms have no heart.

8. Respiratory system- thin-walled skin gills, they partially enter the body cavity. Holothurians have developed specific water lungs.

9. Special bodiesallocation No. Excess substances are excreted through certain cells in the whole. Some of the excretory products accumulate in the skin.

reproductionechinoderms

1. Animals of this type in the vast majority Rseparate floors., found in holothurians hermaphroditism.

2. The gonads are on the sides of each ray.

3. Fertilization is external.

4. Echinoderm eggs are multiple, small, with little yolk. Mother sweeps them into the water, where she goes further development embryos.

5. As a rule, echinoderms emerge from the egg at the blastula stage.

6. Larva dipleurulusA It is bilaterally symmetrical and floats freely in the water.

7. Then begins metamorphosis, it acquires radial symmetry and features of an adult.

They raise many questions, among which the following are of particular interest: "What does a starfish eat?", "For whom does it pose a mortal threat?".

Stars at the bottom of the sea

These unusual decorations of the seabed have existed on the planet for a long time. They appeared about 450 million years ago. There are up to 1600 types of stars. These animals inhabit almost all the seas and oceans of the earth, the water of which is quite salty. Stars do not tolerate desalinated water; they cannot be found in the Azov and Caspian Seas.

Rays in animals can be from 4 to 50, sizes range from a few centimeters to a meter. The life span is about 20 years.

Marine inhabitants do not have a brain, but on each ray there is an eye. The organs of vision resemble insects or crustaceans, they distinguish between light and shadow well. Many eyes help animals hunt successfully.

Stars breathe almost through their skin, so a sufficient amount of oxygen in the water is very important for them. Although some species can live at decent depths of the ocean.

Structural features

It is interesting how they breed, how starfish feed. Biology classifies them as invertebrate echinoderms. The starfish has no blood as such. Instead, the heart of the star pumps sea water enriched with some microelements through the vessels. The pumping of water not only saturates the cells of the animal, but also, by pumping fluid in one place or another, helps the star move.

Starfish have a ray structure of the skeleton - rays extend from the central part. The skeleton of sea beauties is unusual. It is composed of calcite and develops inside a small star from almost a few calcareous cells. What and how starfish eat depends largely on the characteristics of their structure.

These echinoderms have on their tentacles special pedicellaria in the form of tweezers at each end of the outgrowth. With their help, the stars hunt and clean their skins from litter clogged between the needles.

Sly hunters

Many are interested in how starfish eat. Briefly about the structure of their digestive system can be found below. These amazing beauties give the impression of perfect security. In fact, they are marine predators, voracious and insatiable. Their only drawback is their low speed. Therefore, they prefer a motionless delicacy - shells of mollusks. With pleasure, the starfish eats scallop, do not mind eating sea ​​urchin, trepang, and even a fish that inadvertently swam too close.

The fact is that the starfish has almost two stomachs, one of which can turn outward. A careless victim, seized by pedicellaria, is transferred to the mouth opening in the center of the rays, then the stomach is thrown over it like a net. After that, the hunter can release the prey and slowly digest it. For some time, the fish even drags its executioner along with it, but the victim can no longer escape. Everything that a starfish eats is easily digested in its stomach.

She acts somewhat differently with shells: she slowly approaches the dish she likes, braids the shell with her rays, places the mouth opening opposite the slit of the shell and begins to push the valves apart.

As soon as a small gap appears, the external stomach immediately pushes into it. Now the sea gourmet calmly digests the owner of the shell, turning the mollusk into a jelly-like substance. Such a fate awaits any victim eaten, no matter whether the starfish feeds on scallops or small fish.

Features of the structure of the digestive system

The predator does not have any devices for capturing prey. The mouth, surrounded by an annular lip, connects to the stomach. This organ occupies the entire interior of the disc and is highly flexible. A gap of 0.1 mm is enough to penetrate the shell flaps. In the center of the aboral side, a narrow short intestine opens from the stomach. What a starfish eats largely depends on the unusual structure of the digestive system.

The love of the stars at the bottom of the ocean

Most starfish are heterosexual. At the time of love games, individuals are so busy with each other that they stop hunting and are forced to fast. But this is not fatal, because in one of the stomachs these cunning people try in advance to postpone nutrients for the duration of mating.

The sex glands are located near the stars near the base of the rays. When mating, the female and male individuals connect the rays, as if merging in a gentle embrace. Most often, caviar and male germ cells fall into sea water, where fertilization occurs.

In the event of a shortage of certain individuals, the stars can change sex to maintain the population in a certain area.

These eggs most often remain on their own until the larvae hatch. But some stars turn out to be caring parents: they carry eggs on their backs, and then larvae. In certain types of starfish, for this, during mating, special bags for caviar appear on their backs, which are well washed with water. There she can stay with the parent until the larvae appear.

Reproduction by division

A completely unusual ability of starfish is reproduction by division. The ability to grow a new hand-ray exists in almost all animals of this species. A star caught by a predator by the beam can throw it away like a lizard's tail. And after a while grow a new one.

Moreover, if a small particle of the central part is preserved on the beam, a full-fledged starfish will grow out of it after a certain time. Therefore, it is impossible to destroy these predators by cutting them into pieces.

Who are the starfish afraid of?

The representatives of this class have few enemies. No one wants to mess with the poisonous needles of sea celestials. Animals still know how to secrete odorous substances to scare off especially voracious predators. In case of danger, the star can burrow into the silt or sand, becoming almost invisible.

Among those who feed on starfish in nature, large sea birds predominate. On the shores of warm seas, they become prey for gulls. In the Pacific Ocean, cheerful sea otters are not averse to feasting on stars.

Predators harm underwater plantations of oysters and scallops - what the starfish eats. Attempts to kill animals by cutting them apart have led to an increase in the population. Then they began to fight with them, bringing the stars to the shore and boiling them in boiling water. But there was nowhere to use these remains. There have been attempts to make fertilizer from animals that repels pests at the same time. But this method has not received wide distribution.