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

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

(28 photos total)

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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 of Echinoderms, being relatives of sea cucumbers, ophiuras, sea lilies, holothurians, sea urchins - at present there are about 1600 species of them that have a star-shaped or pentagonal shape.

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

5. True, for this animal it will not be difficult to grow new ones for itself, and new stars will soon appear from each ray. How is this possible? - Thanks characteristic feature the structure of a star - each of its rays has the same structure, and contains: two digestive outgrowths of the stomach, performing the function of the liver, a red eye spot at the tip of the ray, protected by a ring of needles, radial bundles of nerves, olfactory organs (they are also suckers and a method of movement) located in the groove on the ventral side of the papules - cutaneous 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) skeleton, consisting of a longitudinal row of vertebrae inside, and hundreds of calcareous plates with thorns 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, being separated from its body, is quite viable and quickly regenerates. Well, when joined 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, which serves as a mouth; bundles of nerves are combined into a nerve ring. The main system of the starfish, which we deliberately left for "dessert", is ambulacral. This is the name of the water-vascular system, which serves as an echinoderm simultaneously for breathing, excretion, touch and movement, together with muscles providing musculoskeletal function. Channels depart from the perioral ring into each ray, from them, in turn, lateral branches to hundreds of cylindrical tubes on the body surface - ambulacral legs containing special ampoules and ending with suckers. The opening in the back, called the mandreopore 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 mandreopore plate into the perioral canal, divides into five ray channels and fills the ampoules at the base of the legs. Squeezing them, in turn, fills the legs with water and stretches them. In this case, the suction cups of the legs are attached to different subjects the seabed - and then sharply contract - 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 mollusks, mussels, oysters, scallops, littorina, sea ducks, reef-forming corals and various invertebrates. The star finds prey by smell. Having found a mollusk, it sticks with two rays to one shell valve, with 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 malleable, the predator opens them open 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 out prey hiding in the sand.

9. With regard to reproduction, most of the starfish are divided into males and females. Fertilization takes place in water, after which free-swimming larvae, called brachiolaria, form. 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), stomach, esophagus and hind gut. Usually, the larvae swim close to an adult starfish of the same species - and after several weeks, under the influence of its pheromones, they undergo metamorphosis: having fixed on the bottom, they turn into tiny (0.5 mm in diameter), but already five-link starfish. And these babies will be able to give offspring only in two or three years. If the larvae perform the function of dispersal of 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 carry their young in a special hatching bag or cavities on the back.

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. No one is at risk of hunting them, since their bodies contain extremely toxic substances - asteriosaponins. Virtually invulnerable, starfish sit at the top of the sea food pyramid and can therefore live up to 30 years. If you believe the scientists, then these brightly colored legendary inhabitants of the seas also make a significant contribution to the process of utilization of carbon dioxide produced by industrial facilities of the planet as well - their share is about 2% CO2, that is, more than 0.1 gigatons of carbon per year. that for such seemingly small creatures, you must agree, is not at all weak!

One of the beautiful animals that cannot be found on land are starfish. Divers who dive in the warm seas often admire these unusual and interesting creatures.

Echinoderms (Echinodermata), which include starfish, are an independent and very peculiar type of animal world. By the structure of the organism, they are completely different from other animals and, due to the peculiarities of the organization and original form bodies have attracted attention for a long time.

Echinoderms appeared on Earth a 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 a glorious and large 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 eat.

In a fossil state, they have been known since the Lower Paleozoic - since the Ordovician period, i.e. about 400 million years ago. More than 1500 known modern species sea \u200b\u200bstars, which are classified into approximately 300 genera and 30 families. Scientists often disagree on the number of starfish orders. Previously, they were combined into three orders - lamellar, acicular, and pedicellarium stars. Currently, they are already divided into 5-9 different groups in various sources. I think that this is not very important for you and me.

Starfish are exclusively marine animals; they are not found in fresh waters. They also do not live in highly desalinated seas, for example, in the Azov or Caspian seas, although sometimes they can be represented by isolated oppressed species. For example, individuals of the A.rubens stars are sometimes found in the western part of the Baltic Sea (near Rügen Island), but they do not breed here, and the population of these sea stars is supported by the larvae brought in by the currents. And the only starfish that has penetrated from the Mediterranean into the Black Sea - Marthasterias glacialis, lives only in its saltiest part - in the Bosphorus Strait.

In seas and oceans with normal water salinity, starfish are found everywhere - from the Arctic to the Antarctic and, 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 kilometers depths, although, of course, at great depths species diversity and the number of starfish is more scarce.
The Russian seas are home to about 150 species of sea stars that live, with very rare exceptions, in the northern and Far Eastern seas.

All sea stars in their adult state lead a bottom lifestyle, crawling along the surface of the bottom or burrowing into the ground. Many of the starfish, especially those living in coastal shallow waters, are active predators, eating various small bottom organisms - molluscs, crustaceans, other invertebrates, including echinoderms, and even fish. They do not disdain carrion either.
Among deep-sea starfish, phylophants predominate - they use sea soil for food, extracting organic matter from it. Some starfish can eat plankton.

Usually, starfish are not very picky about food and absorb everything they can absorb. The diet of, for example, the Chilean starfish Meyenaster includes up to 40 species of echinoderms and molluscs.
Most starfish locate and locate prey from substances that the prey releases into the water. Several soft-bottom starfish, including species of the genera Luidia and Astropecten, are able to locate buried 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, seize small fish, amphipods, and pedicellaria crabs when the prey stops over or near a starfish.

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

The stomach, which turns inside out, is a unique food 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.

Sea stars usually have a more or less flattened body with a central disk gradually turning into rays radially diverging from it. The mouth opening is located on the lower (oral) side of the starfish disc. Most stars have an anus on the upper part of their bodies; in some species it is absent altogether. In the middle of the lower side of each ray 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 sea stars is a five-ray structure, but there are stars with 6 or more rays. For example, the sun starfish Heliaster has 50 rays.

Sometimes the number of rays is different even in individuals of the same species. So, in the sea star Crossaster papposus, 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 disc is also different. In some deep-sea starfish, the rays are 20-30 times longer than the diameter of the disc, while in the common in the Sea of \u200b\u200bJapan Patiria pectinifera, the rays only slightly protrude beyond the disc, which is why the star has the shape of a regular pentagon ... These stars are also called biscuit stars for their resemblance to flat cookies.

There are even known starfish, whose appearance is so changed that it is difficult to recognize them as a star. The common inhabitant of the coral reefs of the New Guinea cult (Culcita novaeguineae) has a strongly swollen body, resembling a strongly swollen pillow or bun in shape. However, this body shape is only in adult stars - young cults have the shape of regular pentagons.
Typically, shallow starfish have a very varied upper body coloration. A wide variety of colors and shades of the spectrum can be present here. Sometimes the colors are spotty and form a bizarre pattern. The abdominal side of the body of starfish is more modest in color, usually 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 colors of starfish depends on pigment inclusions in the cells of the skin epithelium.
Dimensions different types starfish can range from a few centimeters to 1 meter. Most often, divers encounter starfish 10-15 cm in size.
The life span of some species of starfish can be more than 30 years.
The sense 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.

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

Breeding of starfish can take place in several scenarios. If the starfish is cut off the beam with a part of the disk, 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, the connective tissue softens and they break up into several parts, often into two. Soon independent starfish will grow from these parts. The species of the genus Linckia starfish, common in the Pacific Ocean and other regions of the World Ocean, are unique in their ability to cast entire rays. From each such ray, if it is not eaten by a predator, a new starfish can be regenerated. This reproduction is called asexual.

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

Sea stars have no natural enemies. These animals contain poisonous substances in their bodies - asteriosaponins, so predators do not deign to them. In addition, there are few nutrients in the body of a starfish and they do not represent 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), reaching 50 cm in diameter and belonging to the genus Acantasterida, is often found.
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 crown of thorns starfish are notorious among the inhabitants of many tropical islands. It is impossible to pick it up without receiving a burning pain of injections of numerous needles covering the body of a starfish.
A crown of thorns brings a lot of trouble for divers for pearls - if a swimmer accidentally steps on the body of an acantaster, his needles pierce the foot and break off in the human body, infecting the blood with poisonous secretions

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

The crown of thorns, or acantaster 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. Over the years, there have been outbreaks of a significant increase in the number of these sea stars in some regions. Then the very existence of the reefs and their inhabitants was threatened.

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

The useful role played by starfish in the ecology of the oceans and the planet as a whole should be noted. These creatures intensively absorb and utilize carbon dioxide, which becomes more and more in the Earth's atmosphere every year. Up to 2% of atmospheric carbon dioxide is utilized by starfish annually. This is a very large figure.
In addition, starfish are the orderlies of the seabed, eating carrion and the remains of dead marine organisms, as well as weaker and sick individuals of marine animals.

Interesting Facts:

The largest of the 1,600 starfish species in terms of total tentacle span, it is considered 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 maximum weight of all sea stars has a five-pointed Thromidia catalailiving in the western part of the Pacific Ocean. A representative of this species, caught on September 14, 1969 in the Ilot Amedi area of \u200b\u200bNew Caledonia and displayed later in the Noomea aquarium, weighed 6 kg, and its tentacles reached 630 mm
The smallest known was the starfish asterinid ( Patmella parvivipara), discovered by Wolf Seidler on the west coast of Eyre Peninsula, South Australia, in 1975. It had a maximum radius of 4.7 mm and a diameter of less than 9 mm.
The most predatory starfish in the world is the Crown of Thorns ( 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 the sea aveada can be found is considered to be 7584 m deep. At this depth, the Soviet research vessel Vityaz, approximately in 1962, in the Mariana Trench (western part of the Pacific Ocean) 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 (flies) affect the movement of the starfish.

The starfish can eat without swallowing food. For example, when meeting a bivalve mollusk, she grabs it and turns the lower stomach inside out. It enters the shell, envelops the soft parts of the mollusk and digests, and then the starfish simply sucks in the liquefied solution. Spiders act in a similar way - however, they do not know how to turn out the stomach, but simply inject digestive juice into the victim.

Sea stars

classis Asteroidea de Blainville, 1830

These echinoderms usually have a flattened body, smoothly turning 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, reminiscent of tentacles. Unlike lilies, movie stars' mouths and ambulacral grooves are located on the lower surface of the body facing the substrate.


In 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 that move along the substrate using ambulacral legs placed in the ambulacral grooves. Like lilies, movie stars do not have a pronounced anteroposterior 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 the microscope, it is possible to see that pedicellaria is a group of a number of elongated "bones" that work like scissors or forceps. With these tweezers, stars can cleanse 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 detritivores and filter feeders. Cannibalism is also common. When a large prey is captured, the star's stomach is able to turn out of the mouth opening and cover the prey.
The larvae of movie stars are called bipinnaria and brachiolaria, but there are stars with direct development that are capable of carrying their young and taking care of their offspring. Larvae capable of feeding during their own development in plankton are called planktonic larvae, and non-feeding planktonic larvae are called lecithotrophic larvae.
Now there are about 1,500 species of marine movie stars, most of which are inhabitants of tropical seas.
According to our data, 25 types of movie stars live in the waters of South Primorye. Let's talk about the most typical and often encountered representatives of this class of echinoderms.

Luidia two-needle

Luidia quinaria Martens, 1865 bispinosa Djakonov, 1952

This star has a strongly flattened body with 5 long, narrow, tapered rays. The range of the rays of the Luidia reaches 30 cm. From the superficial (dorsal) side, the central disc and rays of the Luidia are dark brown with a violet tint, sometimes almost black, and the lower (ventral) side and sides of the rays are orange-yellow. The upper marginal (marginal) plates are clearly visible along the edges of the rays on the dorsal side. The dorsal surface itself is flat and covered with paxillas 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 beams that are pointed at the ends. The dorsal side is somewhat convex, and the ventral side is completely flat. There are usually 5 rays, although there are 4,6 and even 7-ray patyries. The range of rays of the largest specimens reaches 18 cm.The color of the patyria is very variegated: blue with orange and yellow spots on the dorsal side and orange-yellow on the ventral side. The dorsal side of the patiria is covered with overlapping tiles like a tile, the free edges of which always face the center of the disc. Patiria got their specific name for the scallops of needles located on the ventral side, connected at the base by a soft membrane.
Scallop patyria is a low-boreal-subtropical species, found mainly in the regions of southern Primorye. These stars are very common in the littoral zone among stones and on rocky ground. On sandy, stony and silted soils, patyrias are found up to a depth of 40 m. They prefer to settle on coarse sandy bottom areas with an admixture of pebbles and large stones with clumps and thickets of Zostera and phyllospadex algae. Patiria is a predator that prefers to attack medium-sized mollusks.
In the waters of South Primorye, patyrians spawn in the second half of August and early September. Patiria larvae are planktotrophic.

Solaster pacific

Solaster pacificus Djakonov, 1938

These cold-water stars prefer great depths and are found in southern Primorye, usually deeper than 60-70 m.
Pacific solasters have a wide disc, slightly convex on the dorsal side, from which 7-8 rays, rounded on the sides and slightly swollen, extend, 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 solasters is covered with contiguous bundles of low, different-sized needles, sitting on common bases - paxillas.
The features of reproduction and the biology of Pacific solasters are not well understood. The larvae are lecithotrophic.

Henryk Hayashi

Henricia hayashi Djakonov, 1961

The taxonomy of the genus Henricius is very difficult due to the large number of species and the large species variability of these stars, especially the Pacific representatives, so we do not present a photo of the starfish. For the northwestern part of the Pacific Ocean, 28 species of Henrys were recorded, of which 7 species were noted for the Peter the Great Bay in South Primorye. Henricia live at depths from several tens to several hundred meters.
Henricia are 5-pointed, thin stars with a rough dorsal surface, characterized by a reticulate, looped microrelief on a relatively small central disc and rounded rays. In rare cases, 6-ray stars are encountered. The intravital color of Henricius is usually red, red brick, orange.
We have identified Henrizia Hayashi as the shallowest species that lives only in the Sea of \u200b\u200bJapan and is found in South Primorye at depths of 25 to 45 meters on rocky soils, while other coastal Henricias are usually found deeper than 40 m.The beam span of Henry Hayashi is up to 10 cm.
The peculiarities of Henry's biology are very interesting, namely, the manifestation of care for the offspring. All species of this genus are viviparous and do not have a free-swimming planktonic larva. Before laying eggs, the female attaches herself to underwater objects by rays and lifts the rest of the rays and the central disc, forming a kind of bell. In this confined space, eggs are laid, which develop in balls near the mouth (or even in the mouth of the mother) into the lecithotrophic larval stage, and then into a small star. During this time (usually up to 3 weeks), Henricia the mother maintains her posture and does not eat.

Lysastrosome anthostikta

Lysastrosoma anthosticta Fisher, 1922

This 5-pointed star is easily distinguishable from all others with a "loose", soft body, devoid of the characteristic elasticity of stars as seen in the photograph. The softness of the dorsal cover is explained by the fact that the lysastrosome skeleton plates are very loosely located and do not connect to each other into a single shell. The dorsal surface is uneven and bumpy with thin, sparsely spaced 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 with a soft sheath, to which a bundle of cruciform pedicillaria is attached.
The span of the rays of lysastrosome reaches 22 cm. The dorsal side is red or dark crimson with a prominent yellow madrepore plate. The underside (abdominal) side is light orange.
This species is very widespread in South Primorye, meeting in the littoral zone and at shallow depths on a variety of soils: sand, stony placers, silty substrates, among boulders and in thickets of algae. Lysastrosomes are predators that attack molluscs, crustaceans, and other echinoderms, including sea urchins. The larvae are planktotrophic.

Distolasteria prickly

Distolasterias nipon (Doderlein, 1902)

A very large star with a beam span of up to 45 cm, as can be seen in the photo, often found in South Primorye at depths from 2 to 50 m. Usually 5 long strong rays, tapering at the ends, extend from a small central disk. 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 needles are surrounded by a thick roller of cruciform pedicillaria.
Distolasteriae are very beautiful stars: on the back - velvety black with large bright yellow needles and an orange madrepore plate, and the ventral side is light yellow. They prefer silted soils. Predators. Spawning occurs in late May - early July. The larvae are planktotrophic.

Black Letasteria (photo)

Lethasterias fusca Djakonov, 1931

This seaside 5-ray star is easily distinguished by the black or nearly black color of the central disc and the dorsal rays. 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 range of the rays reaches 23 cm. The rays are dull at the ends, and along the middle of their dorsal side there are a number of wide needles, at the top of which there are small spines.
Letasterians live on rocky reefs, rocky soils at shallow depths (2-50 m). Less commonly found on silted sands mixed with pebbles and stones. Juveniles are found on thalli of macrophyte algae. They lead a predatory lifestyle, attacking medium-sized molluscs, and are often found in oyster houses or on mussel banks. The larvae are planktotrophic.

Aphelasterias japonica Bell, 1881

Distinctive feature of this small seaside star - narrow constrictions detach from the small central disk long, relatively thick, but easily break off rays. The span of the rays, and there are 5 of them in these stars, is up to 24 cm. The plates of the dorsal skeleton and the needles of the aphelasteria are arranged in transverse rows - combs. The dorsal side is bright crimson, often with an admixture of purple tints. The tips of the needles and the ventral side are whitish.
Japanese letasteria are quite common in the littoral zone in the area of \u200b\u200bstone reefs and capes, and are also found on stony soils to a depth of 40-50 m. 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 small mollusks. In South Primorye, aphelasteria spawn in August-September. The larvae are planktotrophic.

Evasteria prickly

Evasterias echinosoma Fisher, 1926

Thorny Evasteria 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. The rays are always 5, 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. Beams of cruciform grasping pedicillaria are located around the needles. It is very easy to make sure of their presence and grip - place the outer part of your palm against the star and pedicillaria will instantly capture the hairs on your hand.
The dorsal side is dark red with a raspberry tinge. Inhabits shallow depths (5-100 m), where it is usually confined to sandy soils with an admixture of pebbles and silt. Less commonly found on clean silts or stones. A predator capable of handling nearly all molluscs and other echinoderms. The larvae are planktotrophic.

Evasteria net

Evasterias retifera f. tabulata Djakonov, 1938

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

Common Amur star

Asterias amurensis Lutken, 1871

The most widespread and frequent starfish in South Primorye. Asteria have a wide central disc, from which 5 wide, flattened, with thin, almost sharp, lateral margins, sharpened at the ends of the rays, extend from which, in large forms, reach 30 cm.The ventral side is very flat. Dorsal needles are small, usually obtuse-conical, single. The largest of them are sometimes located along the middle line of the ray. The color is very variable, varies from ocher to dark purple, but yellowish-brown, sometimes pinkish-brown forms predominate. They are found in the littoral to a depth of 30-40 m, deeper are rare. They prefer sandy and rocky soils. On the littoral, they come across among stones and thickets of algae. On large thalli of algae juveniles of asteria form huge clusters (“kindergartens”), covering the surface of macrophytes with small beads. Large asteria are not uncommon in bays that are very polluted by humans, where other types of stars no longer survive.
Amur stars are predators that attack molluscs (scallops, oysters, mussels) and other echinoderms, and corpse eaters. In places of large concentrations cannibalism is often observed. Sometimes under water you can observe a kind of "balls" of many asterias, stuck to the victim with twisted stomachs.
Of the peculiarities of the biology of asteria, their symbiosis (mutually beneficial cohabitation) with polychaete arctonic worms (Arctonoe vittata) living in the ambulacral grooves of the star is interesting. The worm receives the remains of the predator's food, and in turn eats numerous epibionts (fouling) from the surface of the star, acting as a cleaner.
In South Primorye, the spawning period of asteria is extended and usually consists of two stages: June-July and September. Amur asteria form dense spawning clusters. The spawning behavior of these stars is interesting. Females rise above the ground on the beams and their reproductive products accumulate between the beams in the form of small (2-3 cm) orange hillocks. Males crawl around spawning females, slightly lifting the central part and sweeping out their reproductive products white... Then the stars of both sexes begin to crawl in the area of \u200b\u200bspawning grounds, simultaneously mixing sexual products and protecting them from juvenile fish and various crustaceans. This type of behavior can also be called caring for the offspring. The asteria larva is planktotrophic.

And finally, how the starfish walks.

The seabed is a beautiful place. Bright starfish, exquisite ophiura snake-tails, thick "sausages" of holothurians move along it, sea lilies sway on the rocks, here and there huge needles of sea urchins stick out (don't try to step on it in shallow water!). All these creatures are of the echinoderm type (lat. Echinodermata).

This type includes only marine animals, whose habitat is the bottom of the World Ocean. Most of them are free-living, they can also be attached (for example, sea lilies).

Echinoderms belong to deuterostomes, like chordates. They began their evolution in unimaginable antiquity, even before the beginning of the Cambrian, and now they number about 4 thousand species. The sizes of echinoderms are scattered over a wide range, from 4-5 millimeters to a meter. By the type of feeding, echinoderms are predators and hunt invertebrates.

Echinoderm organ structure and systems

1. Echinoderms are characterized by ray symmetry (in many cases, five-rayed), however, their larvae are bilaterally symmetric, and this suggests that the ray symmetry of adults was acquired a second time.

2. Body covers arranged as follows. Above is ciliary epithelium... Below is the layer connective tissuein which hides calcareous skeleton, giving rise to multiple thorns, 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 looks like three rings with radial nerves. Organs feelings do not have a high level of development, although they are diverse. The organs of touch are andmbulacral legs (a starfish, by the way, can open the shells of mollusks with these legs-handles). At the end of the rays of starfish, eyes are located, and in hedgehogs, eyes surround the anus.

5. Musculoskeletal system... Unique ambulacral The (water-vascular) system serves, among other things, for movement. How does the system work? Radial channels open into an annular channel, from which a shortened rocky channel runs. It passes into the madrepore plate, where water is pumped. Further, the water enters the ring, from which it is sent through radial channels into the rays. Through the radial channels, water fills small capsules lying in the body cavity. They, in turn, turn into small suckers on knife beams. When the capsules are filled with water, the legs are lengthened - 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 below, that is, on the side of the abdomen. It passes into the short esophagus, from which food enters the saccular stomach. By the way, the star can turn the stomach out through the mouth to capture prey! From the stomach to the rays, five pairs of long hepatic outgrowths, ending blindly, are extended. Digestive juice is released from the outgrowths, filling the stomach. Undigested food fragments enter the hind gut and are excreted into the external environment through the anus on the back. Note that in some species of starfish, the stomach is blind-closed, so that food debris is thrown back through the mouth.

7. Circulatory system open, echinoderms have no heart.

8. Respiratory system - thin-walled skin gills, the body cavity partially enters them. Holothurians have developed specific aquatic lungs.

9. Special organs discharge no. Excess substances are excreted through certain cells in the coelom. Some of the waste products accumulate in the skin.

Reproductionechinoderms

1. Animals of this type in the overwhelming majority razdelnopole., in sea cucumbers occurs hermaphroditism.

2. The sex glands are located on the sides of each ray.

3. External fertilization.

4. Eggs in echinoderms 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 dipleurulusand has bilateral symmetry and floats freely in water.

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

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

Stars on the seabed

These extraordinary decorations of the seabed have existed on the planet for a long time. They appeared about 450 million years ago. Up to 1600 types of stars are distinguished. 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 several centimeters to a meter. The life span is about 20 years.

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

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

Structural features

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

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

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

Sly huntresses

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 safety. In fact, they are marine predators, voracious and insatiable. Their only drawback is slow speed. Therefore, they prefer a stationary delicacy - mollusk shells. With pleasure, the starfish feeds on a scallop, does not mind eating a sea urchin, trepang and even a fish that has inadvertently swam too close.

The fact is that the starfish has practically 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 with it, but the victim cannot escape. Everything that a starfish eats is easily digested in its stomach.

She behaves somewhat differently with shells: she slowly approaches the dish she likes, braids the shell with her rays, places the mouth opening in front of the shell gap and begins to move the flaps apart.

As soon as at least a small gap appears, the external stomach is immediately pushed into it. Now the sea gourmet calmly digests the host of the shell, turning the mollusk into a jelly-like substance. Such a fate lies in wait for any eaten prey, it does not matter whether the starfish feeds on a scallop or small fish.

Features of the structure of the digestive system

The predator lacks 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 valves. In the center of the aboral side, a narrow short intestine opens from the stomach. What 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. During 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 sly ones in advance try to save nutrients for the entire time of mating.

The sex glands are located at the stars near the base of the rays. When mating, the male and female individuals connect the rays, as if merging in a gentle embrace. Most often, caviar and male reproductive cells enter seawater, where fertilization takes place.

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

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

Reproduction by division

An absolutely extraordinary ability of sea stars is reproduction by fission. Almost all animals of this species have the ability to grow a new hand-ray. A star, seized 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 remains on the ray, a full-fledged starfish will grow from it after a certain time. Therefore, it is impossible to destroy these predators by cutting them into pieces.

Who are starfish afraid

The representatives of this class have few enemies. Nobody wants to mess with the poisonous needles of the sea dwellers. Animals still know how to secrete odorous substances to scare off especially voracious predators. In case of danger, the star can bury itself in silt or sand, making it almost invisible.

Among those who feed on starfish in nature, seabirds prevail. On the shores of warm seas, they become prey for gulls. In the Pacific Ocean, funny sea otters are not averse to feasting on a star.

Predators harm underwater plantations of oysters and scallops - what the starfish feeds on. Attempts to kill animals by chopping them apart led to an increase in the population. Then they began to fight with them, bringing 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, which at the same time repels pests. But this method was not widely used either.