Sea lily - description, features and interesting facts. Echinoderms: description, names, photos Musculature and ambulacral system

Perhaps the most interesting group of echinoderms are starfish. If the vast majority of other Echinoderms are created
Although the stars are, to put it mildly, inactive, the stars are active predators, spending a significant part of their lives in motion. True, you can’t call them sprinters. A saucer-sized star crawls at an average speed of six meters per hour. But in case of emergency, it can rush for some time at a speed of up to twenty meters per hour. This speed, by the way, is quite enough to catch up with many mollusks. Most stars are predators. Many have a mouth that can stretch wide and swallow whole bivalve mollusks, sea urchins, and their own smaller brethren. There are among the stars and those who are able to turn their own stomach outward, pull it over the victim and digest it without swallowing it. The stomach of these stars is thin and stretches like rubber. A narrow gap between the shells is enough for a star to stick its stomach inside, and the mollusk comes to an end. Many stars create this gap themselves. Having clasped the shell with rays (they are quite mobile in many stars), the star sticks to the valves with ambulacral legs and pushes these valves apart, like Samson's mouth of a lion. As we have already said, it is enough for the star to slightly open the sash. The force that a star the size of a plate develops in this case can reach five kilograms. A normal mussel or oyster is not capable of withstanding such power. Even sufficiently mobile and strong animals, if the star touched them with a beam, find themselves in a peak position - sucking

A starfish clasping a clam shell and trying to open it
the ambulacral legs are held firmly, and the star manages to wrap its rays around the prey before it manages to shake off the echinoderm. There are species of large stars in which the rays are almost as mobile as the tentacles of an octopus, and they even manage to catch fish. True, only the sick or the crippled - a healthy fish is too agile for a star.
Starfish are very gluttonous and bring the owners of oyster jars to hysterics. In many places, oyster colonies have to be fenced off, otherwise delicacy mollusks do not end up in restaurants, but in the stomach of echinoderms. In general, it is very difficult to fight with the stars. It is not enough to catch them, they must also be killed, which is quite difficult. In one of the areas where oyster farming was the main source of income, they somehow tried to collect stars with a dredge, and then chop them into pieces. It ended badly, because from each severed ray a new star grew.

About fifty years ago, the starfish acanthaster caused a lot of panic in the world. This star feeds on coral polyps and destroys them in abundance. Behind the creeping star is a strip of dead coral. Suddenly, for unknown reasons, the number of acanthaster increased catastrophically in many areas and in a number of places they killed corals in areas of several kilometers each. After the death of polyps, coral reefs began to be destroyed by waves, and a threat arose to many small islands that these reefs protected from ocean run-up. An urgent and unsuccessful search for ways to combat this scourge began. But after a few years, the number of stars returned to normal as suddenly as it had grown before, and the danger was over.
Well, in conclusion, it should be said that starfish (and very similar brittle stars), sea urchins and sea cucumbers are the younger generation of the venerable type of echinoderms. From the point of view of the older generation, these are obscenely mobile, restless and cunning creatures. The fact is that the older generation, from which hedgehogs and stars originated, is generally led by a completely motionless sea lily.
lifestyle, similar to the coelenterates. More precisely - led. In our time, only a small class of sea lilies remains from the huge variety of these creatures. And once these ancient echinoderms were numerous in all the waters of the Earth and competed with the intestinal cavities in abundance and diversity.
So the history of echinoderms is unique. Their ancestors were quite normal "worms" who switched to a sedentary lifestyle. It was then that they developed such an unusual body shape and, probably, the nervous system and other organs were greatly simplified. But then some of these creatures, whose structure is superbly adapted to a sedentary existence and deprived of everything that is necessary for movement, for some completely unimaginable reasons, again switched to an active life. And if going into a "sedentary" life is a completely common thing for worms, then a return to a mobile life is an extraordinary rarity.

Echinoderms are represented on reefs by stemless sea lilies - comatulids, holothurians, sea urchins, brittle stars and starfish. These main groups achieve significant species diversity in reef biotopes, with manifestation of endemism in their communities in areas of separate and especially isolated reef systems, such as the reefs of the Red Sea or the Caribbean (Clark, 1976). More than 1000 species of echinoderms live on the Indo-Pacific reefs, about 150 species live on the reefs of the Western Atlantic, and there are only 8 species common to these two large zoogeographic regions. Such isolation of the echinoderm faunas of these regions is similar to the isolation of the faunas of the corals living in them. The endemism of the echinoderm fauna in certain areas is expressed, in particular, in the fact that out of 1027 species inhabiting the Indo-Pacific reefs, there are only 57 species inhabiting this region from end to end. On average, within individual reef systems, there are usually from 20 to 150 species of echinoderms. So, the number of their species in the Red Sea is 48, in the Caribbean - about 100, on the reefs of the Philippines - about 190, in the area of ​​the B. barrier reef - about 160 (Marsh, Marashall, 1983).

The groups of echinoderms listed above, excluding sea stars, form fairly dense communities and monospecific populations on reefs and especially in shallow zones of the lagoon, flat, and outer slope, being the most important element of free-living macrobetos. Their functional role as a component of the reef ecosystem is also great. They occupy all major trophic niches. Among them there are filter feeders (brittle stars, sea lilies), detritophages and ground beetles (brittle stars, holothurians), phytophages (sea urchins) and predators (starfish, as well as partially hedgehogs and brittle stars).

Echinoderms play an essential role in the regeneration of biogens (Webb et al., 1977) and exert a significant influence on the processes of reef genesis. They have a massive calcareous skeleton that makes up up to 90% of their body weight. Their skeletal elements serve as an important source of carbonate material. Eating coral periphyton and spat macrophytes by urchins and stars has a significant impact on the formation of coral communities, as well as eating corals themselves by stars and urchins, especially the star Acanthaster. Holothorn-eaters, passing huge masses of coral sand through their intestines, significantly affect the formation of bottom sediments and the production processes occurring in them. Finally, echinoderms serve as a food source for many mollusks and fish, and holothurians are one of the main objects of fishing on reefs.

At present, we have fairly complete information on the composition and structure of reef echinoderm communities, on the feeding and reproduction of some of their groups (Endean, 1957; Clark and Taylor, 1971; Clark, 1974; 1976; Marsh, 1974; Lisddell, 1982; Yamaguci, Lucas, 1984). Information about their quantitative distribution is very fragmentary. Estimating the population density of most dominant species of hedgehogs, brittle stars, sea lilies, and stars is difficult because these predominantly nocturnal animals hide in shelters of the rock flat during the day and are difficult to count. Therefore, reliable quantitative data are available only for holothurians (Bakus, 1968).

Coral reefs are the traditional habitat of many species of echinoderms. All young individuals of the five-pointed star are males, which, growing up, turn into females! But a multi-beam star is a purely dioecious creature, like most echinoderms. The oldest fossil echinoderm sea lilies - who lived in the Cambrian period, were sedentary creatures in which the mouth opening opened upwards. Feeding on small organisms and food particles floating in the water column, they led approximately the same lifestyle as modern sea lilies.

Echinoderms reached the greatest diversity in the Ordovician and Silurian: the number of their fossil species known to science exceeds 20 thousand. During the Cretaceous period, 300 million years ago, crinoids dominated marine life. Sedentary, fragile and delicate, at first glance, echinoderm crinoids may seem like easy prey for potential predators, but they prefer to stay away from them.

Echinoderm crinoids of coral reefs

Most crinoids accumulate poisonous substances or repellents that repel enemies in their tissues. It is no wonder that in the midst of their fan-shaped petals many small creatures find shelter - from crabs and shrimps to small fish that feed on the remnants of the owner's meal. One sea lily serves as a refuge for a couple of dozen "lodgers".

Reaching a diameter of 60 cm, the multi-beamed starfish, nicknamed the "crown of thorns", feeds on polyps of stony corals, causing terrible devastation in coral reefs. During the period of mass reproduction of these starfish, the Australians bred and released predatory snails on reefs - one of the few natural enemies of the "crown of thorns". The expanded side of the calyx with a mouth opening is turned upwards, and pinnately branched rays up to 30 cm long depart from it.

The supporting skeleton of each beam consists of separate vertebrae - brachial plates, interconnected by movable muscles. The number of rays ranges from 5 to 200, but in most species it does not exceed 10-20. Sea lilies are typical filter feeders. A special groove runs along the beam with all its branches, seated with two rows of ambulacral legs.

The mucus secreted by the glandular cells of the grooves envelops small organisms and organic particles passing by, which the animal feeds on. Ambulacral legs perform only grasping, respiratory and tactile functions.

Many echinoderm sea lilies, primarily deep-sea species, live sedentary, attached to the substrate with a stem up to 2 meters long (in some fossil species, the stem length reached 20 meters). Free-living sea lilies do not have a stem - they swim or crawl along the bottom with the help of their rays or are temporarily attached to the substrate by jointed roots (cirrs) located at the bottom of the calyx.

Almost all sea lilies feed at night, and during the day they hide under stones and in niches among reefs. Today, over 500 species of sea lilies are known. Most of them look the same as their distant ancestors 300 million years ago, and the largest living sea lily reaches 90 cm in diameter.

The body of a starfish consists of a central disk and 5-20 more or less pronounced radially diverging rays. The mouth opening is on the underside of the body. The internal skeleton is formed by movably connected calcareous plates, bearing on their surface skin gills, spikes, tubercles, needles, and special grasping organs - pedicellaria, which are modified needles. The main function of pedicellaria is to clean the skin from dirt.

Let's watch the video - fish, echinoderm sea lilies and stars:

The coral reef is home to a variety of crustaceans, from small crabs hiding between the coral branches to huge spiny lobsters. Most reef crustaceans are brightly colored, providing good camouflage in the colorful coral world.

Lobster in the shape of the body is somewhat reminiscent of crayfish, but is devoid of claws - all legs end in claws. An animal 40 - 50 centimeters long is not uncommon, but it seems even larger due to the stiff whiskers sticking forward with thick bases. The spiny lobster moves along the bottom, slowly moving its legs, and in case of danger it quickly swims backwards, scooping up water under itself with a powerful tail fin. During the day, lobsters hide under overhanging coral slabs, in niches and reef tunnels. Sometimes the tips of the whiskers stick out from under the shelter. When trying to pull the lobster out of the shelter by the mustache, the latter can be pulled out, but the cancer itself cannot be obtained in this way. If the disturbed animal fails to escape, it firmly rests against the walls of its premises. Experienced lobster hunters, having noticed the victim, try to find at least a small hole in the back wall of the shelter, through which a sharp stick is inserted. Slightly pricking the lobster from behind with it, they force the huge crustacean to leave the saving thickets of corals and enter the clear water. When leaving the shelter, the lobster is grabbed by the shell of the cephalothorax, while avoiding the blows of a powerful tail, along the edges of which sharp spikes sit.

An even more ingenious way of catching lobsters is somewhat reminiscent of hunting for burrowing animals with a dachshund, only in this spearfishing the role of a dog is played by an octopus. As you know, this cephalopod is a natural enemy of crustaceans, and therefore the lobster avoids meeting with it by all means. The octopus does not require special training, especially since it, apparently, is impossible. For a successful hunt, it is quite enough to catch an octopus and show it to a lobster, or, by attaching an octopus with a hook to a rope, let it into the shelter of cancer. As a rule, the lobster immediately jumps out and falls into the hands of the catcher, unless, of course, the latter gapes, since the flight of the lobster is always swift.

The lobster feeds on animal food, mainly mollusks, and goes hunting at night. However, in his shelters on the reef, he earns his livelihood in the daytime. Lobsters, as large predatory animals, are never numerous, and therefore their fishing is limited. Due to their high palatability, their meat is universally considered a delicacy. Caught lobsters are delivered alive to consumers. The owners of seaside restaurants in tropical countries willingly purchase lobsters and keep them in cages lowered directly into the sea, where the restaurant visitor can choose any one for dinner.

Not a single coral reef is complete without hermit crabs, and here, like most other reef animals, they are brightly and colorfully colored.

The abundance of gastropods provides hermits with a free choice of shells that are suitable in shape and size. Here you can see red hermits with white flecks, black and white, bluish, green hermits. Some reach considerable sizes and settle in the shells of such large mollusks as the marbled turbo. The heavy shells of trochus also do not remain empty after the death of the mollusk. Hermits with a long, almost worm-like body, which only thanks to this shape can be placed in the narrow passages of the trochus spiral, settle in them. A small and frail hermit can hardly carry a heavy shell, but his efforts pay off with the strength of the shelter. Even in the shells of cones, special types of hermits settle, whose body is leaf-shaped flattened, as if flattened in the dorso-abdominal direction. And the limbs and claws of such a hermit crab are also flat. As elsewhere, hermits feed on a variety of plant and animal foods, not disdaining decaying substances, especially plentiful on reefs polluted by human economic activity. It is safe to say that a large number of small hermits is a sure sign that the reef is in a dysfunctional state.

Small crabs, green, pink, black, brown, live inside coral bushes. Each type of coral has its own set of crabs, merging in color with the bush that gives them shelter. Between the corals, clinging, larger crabs the size of a chicken egg or a few more make their way. Their shells are thick, legs are short with strong claws and powerful claws. Such a crab is not washed off the reef even by strong surf. The color of coral crabs is usually brown or reddish, atergathis has a delicate pattern of thin white lines on its back, erithia is distinguished by large red eyes, the surface of the shell and claws of the actei crab is covered with many tubercles.

All crabs hide in cracks in case of danger, climb into narrow spaces between coral branches. Resting with thick legs against the walls of the shelter, they are firmly held there. To get such a crab for the collection, one has to chip hard limestone with a hammer and chisel. If there are no additional spare moves inside, it is quite easy to catch him. It is much more difficult to catch a flat, fast-swimming talamite crab, which never tries to climb into the gap, and in case of pursuit, flees. It swims with the help of flattened oar-like hind legs.

On the outer slope of the reef crest, among thickets of branched corals, like giant tropical flowers, amazing echinoderms sit, which are called sea lilies. Five pairs of delicate feathery hands slowly sway in the clear water. The small body of a sea lily, located in the center of the "flower", is almost imperceptible. Numerous writhing attachment tendrils, covered from above with hands, cling to the coral. The size of the animal in the span of the arms is about the size of a tea saucer, the colors are mostly dark: cherry, black or dark green; some species are lemon yellow or yellow with black. The spread arms of the sea lily serve to capture food - small planktonic organisms and detritus particles. The mouth opening is in the center of the body and faces upwards.

Sea lilies are inactive. Clinging to the bumps of the corals with their antennae, they slowly move along the reef, and breaking away from it, they swim gracefully, waving their feathery arms. Despite the immobility and harmlessness, it is very difficult to get a good copy of the lily for the collection, since at the slightest touch it breaks off the tips of its hands. Self-mutilation is a characteristic defensive reaction of these echinoderms. When attacked, they sacrifice one or more arms just to stay unharmed; the missing organ soon grows back.

When working on the reef, especially if the body is not protected by a tight overall, you need to be careful not to prick on the thin long needles of the sea urchin diadem. The black body of this apple-sized hedgehog hides in a crevice or under an overhanging coral colony, and bunches of the thinnest needles stick out. When examining a needle under a microscope, it is clear that its entire surface is dotted with the smallest sharp teeth directed backwards. Hard as a wire, the needle of the diadem easily pierces the skin and breaks off there (after all, it is calcareous). With any attempt to pull the needle out of the wound, it only goes deeper into the body. A through channel passes through the needle, and a poisonous liquid enters the wound through it, causing severe pain.

Some reef dwellers use the space between the spikes of the diadem to hide from predators. This is how small cardinal fish from the genera Paramia and Sephamia act. The crooked tail fish (eoliscus) has its narrow body parallel to the hedgehog's needles, and keeps its tail up. The same position is taken by another fish - a hedgehog duck, or diademichthys, which also has a protective color: longitudinal white lines pass along the back, sides and abdomen of the narrow black body of a hedgehog duck, creating the appearance of needles.

Diadems, like many other sea urchins, feed on various algae, in addition, studies that were conducted on the island of Curaçao in the Caribbean, it was recently found that at night diadems get out of their hiding places and eat the soft tissues of reef-building corals. Despite the formidable weapon in the form of poisonous needles, the diadem is not guaranteed from predator attacks. A large blue coral triggerfish, or balistes, easily removes the diadem from its shelter, breaks the shell on the reef and eats the insides.

Fish from the wrasse family swallow small diadems whole with needles, and large hedgehogs are first broken into pieces. The German zoologist H. Fricke conducted an interesting experiment on the reactions of triggerfish and wrasses to the appearance of food objects. It turned out that these fish in search of food are guided solely by sight. They were offered three models: black balls, long needles connected with bunches and balls with stuck needles. Fish always attacked only balls with needles, and did not pay any attention to other models. Wrasses and triggerfishes showed particular activity if the needles on the models moved, as in live hedgehogs.

Wrasses and triggerfish hunt sea urchins only during the daytime, after dark they fall into a deep sleep. Perhaps it is for this reason that the diadems are not shown during the day and are active mainly at night. These sea urchins have another characteristic feature: on flat, open areas of the bottom, they gather in regular groups, with one urchin from the other at a needle-length distance. In search of food, not individual animals move, but the whole group as a whole, which ensures collective protection. The gregarious behavior of diadems is a unique phenomenon in the entire phylum of echinoderms.

Encountering a cluster of diadems does not bode well, but even more unfortunate consequences are contact with a large cherry-red sea urchin Toxopneustes, although it does not have spines at all. This hedgehog, reaching the size of a large grapefruit, has a soft leathery body, on the surface of which there are many small tweezers, the so-called pedicillaria. All sea urchins and stars have similar tweezers; with their help, animals clean the surface of the body from trapped particles of silt and other foreign objects. In needleless Toxopneustes, pedicillaria play a protective role. When a sea urchin sits quietly on the bottom, all of its tweezers slowly swing from side to side, opening the valves. If any living creature touches the pedicillaria, it will be immediately seized. Pedicillaria do not loosen their grip while the animal is moving, and if it is too strong, they come off, but do not open their valves. Through the puncture of the tweezers, a strong poison enters the wound, which paralyzes the enemy. This is how toxopneustes escape from attack by starfish and other reef predators.

For humans, the poison of this sea urchin is also dangerous. The Japanese scientist T. Fujiwara, investigating Toxopneustes, received only one prick of tiny tweezers. Subsequently, he described in detail what happened after the defeat. The pain from the bite quickly spread through the arm and reached the heart, followed by paralysis of the lips, tongue and facial muscles, then followed by numbness of the limbs.

The patient became somewhat better only after six hours.

Luckily, Toxopneustes is relatively rare, but still well known to the locals. Fishermen in the southern islands of Japan call Toxopneustes a killer, as there are known cases of fatal defeat of people by this sea urchin.

It is noteworthy that the sea urchins tripneustes, closely related to Toxopneustes, also living on reefs, are completely harmless. In the Caribbean on the island of Martinique, they are even eaten. The hedgehogs collected on the reef are broken and the caviar is taken out of the shell, which is then boiled until a thick pasty mass is obtained. The finished product is filled with empty shell halves and the delicacy is peddled.

The population of Martinique consumes so many hedgehogs that in some places whole mountains have formed from the shells, like the kitchen piles of clam shells left by the ancient population of Europe.

In heterocentrotus, not everyone recognizes a sea urchin. It has an unusually colored brown-red body, of the same color and thick needles resembling cigars in shape and size, each with a light wide keel near the outer end. Heterocentrotus sits, huddled in a narrow crack, on the most surfy place of the reef. With thick needles, he firmly rests against the walls of his shelter.

Small sea urchins with their short green needles drill small caves in the coral. Often the entrance to the cave is overgrown, and then the hedgehog is walled up alive in his shelter.

Starfish live on the coral reef. Here you can see a beautiful bright blue linkia with thin straight rays and a brown culcite that looks like a loaf of round bread. The spiked tricolor protoreasters are very spectacular, but the most famous starfish of coral reefs is, of course, the crown of thorns, or acanthaster.

Among the colonies of corals in the water, giant sea anemones stoichactis slowly sway with their tentacles. The diameter of the oral disk of such an anemone, together with thousands of tentacles, sometimes reaches a meter. Between the tentacles, either a couple of colorful shrimps, or several fish - sea clowns, or amphiprions are constantly hiding. These cohabitants of the stoichactis are not at all afraid of its tentacles, and the anemone itself does not react in any way to their presence. Usually the fish stay close to the anemone, and in case of danger they boldly dive into the very thick of the tentacles and thus avoid pursuit. In total, over a dozen species of amphiprions are known, but representatives of only one of them hide in each sea anemone, and the fish jealously protect "their" sea anemone from the encroachments of other species.

Above, we have already talked about some fish living in the coral biocenosis. In total, over 2500 species are known. As a rule, they all have a bright color, which serves as a good disguise for fish in the colorful coral world. Many of these fish feed on corals by biting and grinding the tips of branches.

For catching coral fish, there is a fairly simple, but very reliable technique. On a clearing between the bushes, a fine-mesh net is spread and several branches of coral are crushed into its center. Immediately, many fish rush to this place, attracted by their favorite food. It remains to take the net out of the water, and for sure some of the fish will be caught. Attempts to get coral fish with a net always end in failure. On the reef, everything is solid and motionless, so every moving object is fraught with a potential threat. Coral fish hide from the approaching net in thorny thickets, and it is no longer possible to expel or lure them out of there.

A lot has been written about the beauty of coral fish, but all descriptions pale before reality. When a small color film was made after the first Soviet expedition to the coral reefs of Oceania, many viewers, including biologists who had never seen live coral fish before, mistook natural filming for color animation.

Certain fish species of the coral biocenosis are poisonous. Very beautiful pink lionfish with white stripes and the same color with rays of fins are kept in sight, as they are protected by a whole series of poisonous spikes. They are so sure of their immunity that they do not even try to escape persecution.

An inconspicuous stone-fish lies quietly at the bottom, half buried in coral sand. It is easy to step on it with a bare foot, and then the matter can end very sadly. On the dorsal side of the body of the stone-fish there are several poisonous glands and short sharp spikes. The poison that gets into the wound causes severe pain and general poisoning. As a result of paralysis or heart failure, the victim may die. Even in the case of a favorable outcome, full recovery occurs only after a few months.

To put an end to the dangers that await man on the reef, it is also necessary to say about sharks and moray eels. Sharks often visit the space above the reef or stay close to its outer edge. They are attracted to various fish that feed on the reef, but sharks have been known to attack pearl divers. Serpentine moray eels, sometimes reaching solid sizes, hide in the reef itself. Very often, the head of a large moray eel with a slightly open toothy mouth sticks out of the crevice. This strong and cunning fish can inflict large cut wounds with its razor-sharp teeth. In ancient Rome, rich patricians kept moray eels in special pools and fattened them up for festive feasts. According to some legends, it is known that the guilty slaves were thrown into the pool with large moray eels, and the fish quickly dealt with them.

Now let's talk about what threatens the existence of coral reefs, which can cause their oppression and death. In their book The Life and Death of a Coral Reef, Jacques-Yves Cousteau and journalist Philippe Diole touch on this important issue. In their opinion, the main reason for the death of reefs today lies in the imprudent economic activities of man. However, we should not forget that reefs most often die as a result of natural disasters.

Throughout the last week of January 1918, continuous heavy rains fell on the coast of Queensland. Streams of fresh water hit the shores, the sea and the Great Barrier Reef. These were the heaviest showers ever recorded by the Australian weather service: 90 centimeters of precipitation fell in eight days (for comparison, we point out that in Leningrad, which is famous for its humid climate, only 55-60 centimeters fall in a year). As a result of heavy rains, the surface layer of the sea was freshened, and during low water, streams of rain whipped right on the corals. The sea began on the reef. Corals, algae and attached inhabitants of the coral biocenosis died. Mobile animals hurried to go deeper, where desalination was not felt so strongly. But the calamity spread deep into

well: the rotting of dead corals caused poisoning of the water near the reef and caused the death of many of its inhabitants. Many sections of the Great Barrier Reef were dead. It took several years to restore them.

In January 1926, heavy rains destroyed coral reefs near the islands of Tahiti, and in 1965, heavy rains caused the death of a rich reef in the bay of Tongatapa Island in the Tonga archipelago.

As a result of showers, coral reefs usually die over a significant area, since heavy and prolonged rains capture entire areas, and not individual limited areas.

The coral reef, destroyed by rains, after a while is restored in its original place. Fresh water, although it kills all life on the reef, does not destroy the coral structures. A few years later, the skeletons of dead corals are overgrown with new living colonies, and the reef is reborn in its former glory.

The situation is quite different in hurricanes. It is known that severe storms periodically occur in tropical seas, which sometimes take on the character of natural disasters. The story about the causes of hurricanes, about their destructive power and consequences is yet to come, here we will only talk about the impact of hurricanes on reefs.

In 1934, a cyclone destroyed a coral reef off Lowe Island in Australia's Great Barrier Reef. The wind and waves literally left no stone unturned: everything was broken, mixed up, and the fragments were covered with sand. The restoration of the reef was very slow, and after 16 years, in 1950, young coral settlements were swept away by a new cyclone.

The strongest damage to the reef was caused by a severe hurricane that hit the coast of British Honduras (Caribbean) in 1961. An equally strong cyclone destroyed a reef on Heron Island (Great Barrier Reef) in 1967. It so happened that it was on this small island that, shortly before the disaster, a Biological Station belonging to the Australian Committee for the Study of the Great Barrier Reef was organized. Scientists had not yet had time to seriously examine their new possessions and describe the reef of the island of Heron, as there was not a trace left of it. Their further work began with the study of reef recovery after the disaster.

Destructive cyclones have a limited range. If prolonged heavy rains come in a wide front, then the path of the cyclone is a relatively narrow strip. For this reason, it destroys only certain areas or small reefs, while the neighboring ones remain intact.

What happens on the reef during the passage of a cyclone? The most comprehensive answer to this comes from Peter Beveridge, an employee of the University of the South Pacific, who examined one of these destroyed reefs immediately after a hurricane named Beebe visited there in 1972. "Bibi" walked widely in the western part of the equatorial zone of the Pacific Ocean. Its epicenter was crossed by the Funafuti atoll, the same atoll on which drilling was carried out to test the theory of Charles Darwin. Immediately after the disaster, P. Beveridge left his comfortable office of the dean of the preparatory faculty in Suva, the capital of Fiji, and went to distant Funafuti. He saw a picture of complete destruction. A thriving tropical island was virtually destroyed. Slender coconut palms - the basis of the food of the islanders - are thrown to the ground. Locals said that waves rolled over houses and broke trees. In order not to be washed into the ocean, people tied themselves to the trunks of palm trees, but this measure did not save everyone. Funafuti Atoll consists of several islets and a series of reefs surrounding a lagoon with a diameter of about 20 kilometers. In windy weather, solid waves walk along the lagoon, during a hurricane they reach a gigantic size. But even larger were those ramparts that approached from the open ocean. Coral reefs are known for their strength and endurance, but they did not resist. Separate detached colonies or their fragments rolled over in waves and played the role of cannonballs. They broke up living colonies and spawned new debris, which in turn bombarded the reef. The hurricane washed up new shoals, covered the former living areas of reefs with fragments of coral and sand, created new channels between the islands and erected new islands from the reef debris. The whole atoll has changed. The coral settlements on Funafuti were described in detail by an English expedition of 1896-1898; in 1971 they were examined by a complex expedition of the USSR Academy of Sciences on the research vessel "Dmitry Mendeleev". For 75 years, they have not changed much. After "Bibi" the description of these reefs needs to be done again.

There are known cases of the death of the reef under the flows of liquid lava pouring into the sea from the mouth of an active volcano. So the coral reefs around the volcanic island of Krakatoa near Java were destroyed, when on August 26, 1883, the most powerful volcanic eruption in the history of mankind occurred. After a terrible explosion, which was heard even on the coast of Australia, a column of steam more than 20 kilometers high rose from the mouth of the volcano, and the island of Krakatoa itself turned into a mass of red-hot lava and stones. All life perished in the boiling water. But even smaller eruptions can cause the death of the reef. So, the coral reef died in 1953 during the eruption of one of the volcanoes in the Hawaiian Islands.

Earthquakes pose a threat to living coral reefs. One such disaster occurred off the coast of New Guinea, near the small seaside town of Madang. On the night of October 30 to November 1, 1970, powerful tremors shook the city and the bay. The epicenter of the earthquake was in the sea, so the town was not affected, but the reef was destroyed for several kilometers. From the first blows, thin delicate branches of bushy and tree corals broke off and collapsed to the bottom. Massive spherical colonies broke away from the substrate, but at first remained in their places. The earthquake was accompanied by sea disturbance caused by tremors. As coast watchers testify, the sea first receded, and then rapidly rose 3 meters above the normal level at high tide. The outgoing and rolling waves swept flat leaf-shaped and disc-shaped colonies. Meter and larger coral balls torn from the bottom began to move. Rolling over the reef, they completed the destruction. Many such colonies rolled down the slope of the ridge, while others, although they remained close to their places, were turned over. In a few minutes the reef ceased to exist. What was not broken and crushed was buried under a layer of rubble. Individual surviving animals of the coral biocenosis died in the days following the catastrophe as a result of water poisoning by a mass of decaying organic substances.

A terrible threat to coral reefs lies in the invasion of hordes of predatory starfish, which scientists call acanthaster planzi, and the press and popular science literature dubbed the "crown of thorns." More recently, until 1960, the “crown of thorns” was considered a rarity, but in 1962 not only zoologists, but also journalists and statesmen started talking about it. Having unexpectedly multiplied in myriad numbers, the "crowns of thorns" strangely changed their tastes and switched from feeding on mollusks to destroying reef-building corals. Many reefs of the Pacific Ocean, including the Great Barrier Reef of Australia, have been massively attacked by starfish.

An urgent intervention was needed to save the corals, but no one really knew what exactly should be done. Even about the starfish itself, science had very scarce information. And so scientists from different countries and various specialties rushed to the coral reefs in order to learn as much as possible about the insidious "crown of thorns" and find its Achilles' heel. Acanthaster is one of the largest sea stars: individual specimens reach 40 - 50 centimeters in the span of rays. Young stars of this species have a typical five-ray structure, but as they grow, the number of their rays increases and in old specimens reaches 18 - 21. The entire dorsal side of the central disk and rays is armed with hundreds of mobile, very sharp spines 2-3 centimeters long. Thanks to this feature, the acanthaster got its second name - the “crown of thorns”. The body of the star has a grayish or blue-gray color, the spikes are red or orange.

Acanthaster is poisonous. The prick of its thorn causes burning pain and subsequent general poisoning.

The Crown of Thorns is able to move quite quickly and climb into the narrow spaces between the corals, but usually these stars lie quietly on the surface of the reef, as if they are aware of their impregnability. They reproduce by spawning a mass of tiny eggs into the water. Prof. Frank Talbot, director of the Sydney Zoological Museum, and his wife, Suzette, conducted a special study on the biology of the crown of thorns, a well-known coral reef explorer. They found that on the Great Barrier Reef, acanthaster breeds in summer (December - January), and the female spawns 12 - 24 million eggs. The larvae stay in plankton, and various planktonic predators can feed on them, but as soon as the larvae settle to the bottom to turn into a young star, they become poisonous. There are few enemies at the "crown of thorns". It is reliably known that these stars are eaten by large gastropod mollusks charonia, or triton. Acanthasters are distributed throughout the tropical zone of the Pacific and Indian Oceans.

Like many other starfish, the "crown of thorns" is a predator. It swallows small prey whole, and envelops larger animals with its stomach turned outward through the mouth. When feeding on corals, the star slowly creeps along the reef, leaving behind a white trail of coral skeletons. As long as these stars are few in number, the coral community hardly suffers from them. It is estimated that up to 65 "crowns of thorns" can feed on one hectare of reef without harm to it. But if their numbers increase, corals are threatened with destruction. The Talbots point out that in the area of ​​the outbreak, acanthasters feed around the clock. Moving along the reef in a continuous front at a speed of up to 35 meters per day, they destroy up to 95 percent of corals. After the devastation of the reef, the stars suddenly disappear, but soon appear on neighboring reefs, crawling along the bottom of the deeper sections that separate one reef from another.

Some zoologists were inclined to see the cause of the disaster in the violation of natural relationships on the reef by man. It was assumed that the mass production of large newt mollusks with a beautiful shell for souvenirs led to an increase in the number of starfish. After all, the triton is almost the only enemy of the “crown of thorns”. It was also assumed that the catch of small chimenocera shrimp also contributes to the reproduction of predatory stars. There were reports in the press that someone saw how these small crustaceans, having gathered in a whole flock, arrange dances on the back of the star and jump until the exhausted “crown of thorns” draws in its numerous legs with suction cups. Then the crustaceans climb under the star and eat away the non-poisonous soft tissues of the underside. However, none of the scientists have observed this. Newts are indeed capable of eating starfish, but these large mollusks are never found in large numbers, and their role in regulating the number of "crowns of thorns" is negligible. To save the reefs, the governments of many countries have banned the catching of newts and the sale of their shells, but the situation on the reefs has not changed.

The scale of destruction in a short time has reached an unprecedented magnitude. Several teams of specialists from Australia, England, Japan and the USA surveyed 83 Pacific reefs. By 1972, a total of about a million pounds sterling had been spent on these expeditions and on developing measures to combat the star. Meanwhile, the stars continued to multiply. Control calculations in the Hawaiian Islands showed that one scuba diver can count from 2750 to 3450 "crowns of thorns" per hour. Attempts to destroy the acanthasters with poisonous substances or to enclose the reefs with bare wires through which an electric current is passed did not lead to the desired results. There were voices of scientists about the need to strengthen control over ocean pollution.

The first observations of the "crown of thorns", carried out by Soviet scientists during a special "coral" voyage of the research vessel "Dmitry Mendeleev" in 1971, convincingly showed that acanthasters mainly attack weakened reefs polluted with household and industrial waste, as well as oil products. The Australian zoologist Professor Robert Endin, the head of the work on the study of the Great Barrier Reef, came to similar conclusions. In 1973, R. Endin and R. Chisher, an employee of his laboratory, came to the conclusion that most often the areas of outbursts of the number of stars and the destruction of reefs by them are located in the immediate vicinity of human settlements. On reefs far from settlements, there are no outbursts in the number of stars.

Not everyone agreed with this opinion. So, one of the commissions created in Australia, contrary to the evidence, came to the conclusion that the “crowns of thorns” are practically harmless for the reef. However, this commission was under strong pressure from oil companies seeking permission to drill wells in the Great Barrier Reef. This is stated in an article by the zoologist Alcolm Hazel, published in 1971 in the journal "Bulletin of the Marine Pollution".

Not only individual companies, but also government officials were involved in the range of issues related to the “crown of thorns”. In 1973, the US Congress passed a bill allocating $4.5 million to carry out a program to study this problem and develop appropriate measures to control the situation. It is unlikely that congressmen would so easily part with these funds for the sake of pure science or some exotic reefs. It is quite obvious that behind them stood the magnates of industrial capital, primarily the oil firms.

Summing up the review of the causes of the death of coral reefs, we must also add the direct destructive effect of ocean pollution on them. Finally, several reefs fell victim to atomic tests. So sadly ended the existence of all life on the Eniwetok Atoll, where nuclear weapons were repeatedly tested. Zoologist R. Yoganess, who surveyed Eniwetok 13 years after the explosion, found only small colonies of four coral species on the reef.

The rate of reef recovery, or rather the birth of a new coral biocenosis, is different and is directly dependent on the cause that caused the death of the old reef. It is difficult to expect a complete restoration of coral reefs that have been oppressed or destroyed by human economic activity. Sea pollution near settlements and industrial enterprises is continuous and has a clear tendency to increase. The reef is recovering very slowly after the hurricane, as the foundation on which the coral biocenosis develops is destroyed. Even more significant changes in the structure of the bottom are caused by a nuclear explosion, to the mechanical action of which radiation is also added. It is clear that R. Ioganess found only miserable crumbs of life on Eniwetok Atoll, although 13 years have passed since the disaster. Reefs that have died as a result of rainstorms or earthquakes recover relatively quickly. There are extremely few regular repeated observations of the development of such a reef, the most interesting and important according to the results of the study were carried out by Soviet expeditions on the Dmitri Mendeleev and Vityaz.

A reef was taken under observation in the bay near the city of Malang in New Guinea. A group of scientists visited it three times - in 1971 (8 months after the devastating earthquake), then in 1975 and 1977.

During the first year, algae predominate on the recovering reef; they cover all the coral fragments lying on the bottom with an almost half-meter loose layer. Among bottom attached animals, sponges predominate, and there are some small colonies of soft corals. Reef-forming corals are represented by several species with thin branches. Colonies of these corals are attached to the fragments of dead polyps and reach a height of only 2 - 7 centimeters. For every square meter of the bottom there are no more than 1 - 2 of these small colonies.

A year or two passes, and algae give way to sponges. After another year or two, soft corals predominate on the reef. All this time, hermatypic (reef-forming) madrepore, hydroid and sun corals are slowly but steadily gaining strength. 4.5 years after the destruction, almost no algae remain on the reef. They cemented the debris into a solid mass and gave way to sponges and soft corals. By this time, corals with a limestone skeleton occupy the second place on the reef both in terms of the number of colonies and the degree of bottom coverage by them. After 6.5 years, they already dominate the biocenosis, occupying more than half of the living space. The lips are strongly suppressed and pushed aside. Soft corals are still resisting, but their fate is sealed: it will take a few more years, and the reef will fully recover in all its former beauty.

Coral reefs play a huge role in the life of the population of coastal tropical countries, in the life of the peoples of Oceania. The inhabitants of the islands live on the fruits of the coconut palm, vegetables from their small gardens and seafood that they get on the reef. Here the islanders collect edible algae, mollusks, echinoderms, fish and crustaceans. Animal husbandry on the islands of Oceania is poorly developed, and the reef serves as the main source of protein food for the population. Coral limestone is used in construction. From the shells of coral mollusks, a variety of household items, tools, tools, jewelry, and religious objects are made. The reef, taking on the blows of the waves of the surf, protects the shores of the islands from erosion, where aboriginal huts, palm groves and vegetable gardens are molded on a narrow strip of land. It is believed that life on tropical islands would be impossible without coconut trees. In the same way, it is impossible without coral reefs.

In the vast expanses of the salty ocean desert, coral islands are real oases, in which life is saturated to the limit. The reasons for the high biological productivity of the reef are not yet fully understood, and it is very important to find out. Every year the role of marine underwater farms is increasing, but so far they are still unprofitable. In order to increase their productivity, it is necessary to understand the reasons for the high productivity of some natural marine biocenoses, primarily coral reefs.

In connection with the rapid growth of the Earth's population and the increase in human economic activity, there is a threat of destruction of many natural complexes of plants and animals. Reserves are organized everywhere for their protection. The first coral reserves have also been created, but there are still very few of them, and reefs need protection no less than other natural communities.

Coral reefs, which support the existence of millions of people, are of such fabulous beauty and are so sensitive to the most diverse forms of influence, must be preserved.

Type Echinodermata represented by various marine creatures, from biscuits (flat sea urchins) to starfish, cirrus stars, sea cucumbers - they all belong to five broad classes of this type. This month we will look at representatives of only one of these classes, or rather, we will talk about brittle stars: “brittle stars”, serpenttails and Gorgon heads. All of them belong to the class Ophiuroidea; however, some of them are regularly found for sale, while others are "hitchhikers" who accidentally end up in our aquariums.

Many brittle stars outwardly resemble starfish belonging to the class Asteroidea(aka asteroids), but brittle stars are a completely different group of echinoderms for a variety of reasons. Therefore, today I will talk about some of the characteristics that unite these creatures, as well as why brittle stars belong to a separate class, and then I will share information about keeping them in aquariums.

Echinoderms. basic information

First, let's talk about the main characteristics of echinoderms. As I said, there are various echinoderms, and some of them look completely different. However, if you look closely, some physical characteristics that are typical of the entire group become apparent.

First of all, their bodies/body parts are arranged around a central axis. Regardless of the presence or absence of "hand-rays" (as in starfish), their body shape is usually round or rounded with limbs branching from the center. This form is called ray symmetry; it is this structure that is characteristic of cnidarians (corals, sea anemones, jellyfish, etc.). Echinoderms and cnidarians are characterized by a round (rounded) body shape and a centrally located mouth; many have numerous "arms"/tentacles radiating from the center. However, in fact, this is where the similarity between representatives of the Echinoderm type and the Cnidarian type ends.

The ray body of echinoderms can be divided into five approximately equal parts, or a multiple of five, while the body of cnidarians is usually divided into six or eight, or a multiple of six or eight. More specifically, it is correct to say that echinoderms are characterized by five-ray symmetry, and not just radial symmetry, since the number of body parts is a multiple of five. However, there are rare exceptions to the fivefold structure rule. For unknown reasons, there are occasional varieties of starfish with six or seven rays, or any number of rays other than a multiple of five, but they are considered "white crows".

Despite the fact that all echinoderms are characterized by five-fold ray symmetry,
there are exceptions, such as these "asteroid" starfish, with 6 and 7 "arm-rays".

Further, all echinoderms also have a unique ambulacral system - a complex system of muscles, canals, pouches (sacs), cavities, tubes, and suckers - that allows them to move and/or feed. It also acts as a circulatory system (cardiovascular system) as these animals lack gills, blood, and a heart. If you've ever looked closely at a starfish and noticed the rows of little sucker legs on the underside, then you've already seen part of this system. They have hundreds of cup-shaped suckers - "tube legs" that emerge from grooves in the underside of their bodies that are used for both locomotion and feeding. Conversely, tubular legs of the same type emerge from the rays of the brittle stars and are used for grasping food, but they lack suckers and are not used for locomotion. Below we will talk about this in more detail.

If you look at the lower body of a starfish (asteroid), you can see tubular sucker legs,

which are the hallmark of the ambulacral system.

Finally, echinoderms have a kind of skeleton that is composed of the mineral calcite (CaCO3) and is covered by an epidermis (outer covering). In the case of starfish and all brittle stars, this calcite (limestone) skeleton is made up of numerous individual plates called "ossicles" that are held together by special connective tissues that can be very soft or very hard. This structure provides them with flexibility or rigidity if they tense the body, as in the case of a defensive reaction. Other echinoderms such as sea urchins and biscuits (flat sea urchins) also have skeletons of plates that are joined to form a shell, which is properly called a shell. If you get a chance to take a closer look at the "shell" of a dead sea urchin, you'll notice that it is made up of individual plates held together by ligaments similar to those that hold the bones of a human skull together. However, in other echinoderms, such as sea cucumbers, the skeleton is simple (underdeveloped) and is nothing more than a few small, strangely shaped calcite plates embedded in a thick skin of connective tissue.

Asteroids and brittle stars

Having considered some similarities, it's time to explain why starfish and brittle stars belong to different classes. Most brittle stars may look like starfish at first glance, but in fact, there are significant differences between representatives of these two classes. First, the brittle stars are characterized by long, thin "arm-rays", which clearly stand out from the main, organ-containing body, which, as a rule, is small and rather flat. On the contrary, the body of asteroids is not pronounced, there is no clear boundary of the body and the beginning of the rays. In addition, the brittle stars have only five rays, which are used for nutrition and movement. Unlike asteroids, brittle stars do not use their tubular legs at the bottom of their beams to move, but crawl with their arm-beams (although there are a few exceptions1). Due to this, their speed of movement is much higher than that of asteroids; some buffoons move surprisingly fast.

Many asteroids feed by turning their stomach outward, which is very convenient for species that feed on molluscs. They have to use their tube feet with suction cups to open the clam shell a little, and then they turn their stomach inside the shell to complete the process. However, brittle stars do not have an eversible stomach, so they cannot feed on shellfish (at least in the same way) or many other types of food available to asteroids.

However, many of them are successful scavengers and predators, eating a variety of worms, snails and crustaceans. Some are even able to use their arm-beams to hold their bodies above the bottom, waiting for small fish or other prey to swim or crawl under them. Then the trap closes, the rays converge at the bottom and the body quickly descends on the prey. Accordingly, the victim is under the mouth, with the help of which it is absorbed. Others feed on detritus: they move along the bottom, picking up the remains of fish waste and the like, and some burrow into the ground, if possible, extracting available food.

The "Gorgon's head" buffaloes are rather unique, as they feed on particles suspended in water: they open their rays in the stream of water and catch everything that falls into their hands. In this way, they are able to capture anything from large zooplankton to small fish, and then move the prey to their mouths and consume it. Certainly, this way is different from the way any asteroids are fed.

The ophiurs "Gorgon's head" are unique: during the day they are twisted into a ball,
and at night they spread their very branched "arm-rays";
They feed mainly on large zooplankton.

Speaking of class Ophiuroidea, for the most part, it is not difficult to distinguish three main types of representatives. Only at first glance, many "brittle stars" and serpentine are outwardly similar, but the main external difference between them is the absence of any processes on the rays of serpentine. The rays of "brittle stars" are more bizarre and are usually covered with many spines, spines and/or processes of various shapes and sizes, while the rays of serpenttails are relatively smooth and usually without additional "decorations", they more closely resemble the body of a snake.

Ophiurs (besides the “Gorgon heads”) with rather bizarre ray arms are called “brittle stars” (left),
while brittle stars with relatively smooth ray arms are often referred to as serpenttails (right).

Such a separation of "brittle stars" and serpents, in fact, is not biological and is not based on real taxonomic differences between these two groups of brittle stars. This difference is based on appearance, so some aquarists, divers, etc. may call various representatives of brittle stars or serpents, while others call all brittle stars, regardless of their appearance. Don't get confused if you come across different names. In fact, there are some brittle stars whose appearance is in the middle between the groups described, with smooth discs and only one or two rows of relatively small processes on the rays. However, the "head of the Gorgon" brittle stars are characterized by the presence of five rays, especially long and thin, branched at the base and further and more and more branched along the entire length.

In aquarium

For starters, as mentioned above, various brittle stars are carnivores, scavengers, and also feed on detritus or particles suspended in water. In fact, most of them eat several ways, although they usually have a main/preferred way of eating. 1 This flexible approach indicates that it is usually easy to keep them alive.

As far as I can tell, brittle stars and serpenttails can be fed with any fish food, in particular, particles of fish meat, shellfish or shrimp, various pellets sinking to the bottom; as a rule, brittle stars quickly capture such food. In one of my aquariums there are two brittle stars that hide in the masonry most of the time, but when flakes are nearby, they grab them with their ray arms. The only thing that I usually observe is thin "hands" that appear between the stones at the bottom and from time to time catch something.

In any case, aside from occasionally grabbing fish food, even these surprisingly large specimens, a few inches in diameter, appear to be able to find enough fish food leftovers to sustain themselves. And as far as I know, they have never claimed to be inhabitants of my aquarium, nor have other small to medium sized "brittle stars"/serpenttails ever inhabited my aquariums.

However, I have read and heard that some of the most commonly sold small-to-medium sized brittle stars/serpenttails will not refuse to snack on one particular type of invertebrate commonly found in reef aquaria, tube fan worms such as Bispira sp. . Apparently, some species do not actually extract these worms from their tubes and eat them.4 Therefore, this aspect must be kept in mind if you keep or intend to keep brittle stars in your aquarium.

Small to medium sized brittle stars/wyrmtails such as Ophiocoma echinata,
usually without problems can be kept in aquariums.

On the other hand, larger brittle stars/wyrmtails can sometimes create problems. Many of them are predominantly detrital feeders, like most brittle stars, but some are carnivorous, so some large species will eat anything from small fish and shrimp to hermit crabs.4 I have already covered the main methods above. capture fish, in the form of a trap, but many other types of prey are simply captured by ray arms and eaten.

I had a very large red serpentine, Ophioderma squamosissimus, who smelled the fish food I was adding to one of my non-reef tanks and immediately emerged from under the (dead) coral that served her as a shelter, stood up on two beams and held her body in this position, waving the rest of her arms - rays in the hope of getting food. A few dropping shrimp pellets were enough to keep her growing and living, but when I once discovered a missing damselfish, I doubted if the ophiura had caught it.

red vipertail, Ophioderma squamosissimus, - an example of a large serpentine,
feeding on many other mobile invertebrates and small fish,
therefore, such brittle stars are best kept away from reef aquaria.

I definitely wouldn't put it in a reef tank for fear that it could knock over anything and anyone in the tank that isn't heavy enough for it to budge. My brittle star was about a foot in diameter and moved faster than you might think, just like some others, in particular the green "brittle stars" that are regularly found on sale. Ophiarachna incrassate; they can reach large sizes, sometimes over a foot and a half in diameter.5 Therefore, before introducing a large species into an aquarium, take into account the possible size and diet of brittle stars.

Green "brittle star" Ophiarachna incrassata, - one of the most common in the aquarium market;
they can reach incredibly large sizes.

I would also refrain from introducing any creatures of this size into a reef tank as
they are able to overturn everything that comes in their way.
Of course, they will also eat many mobile invertebrates and small fish.

In addition to these animals, although you are unlikely to find them for sale, there are numerous species of "brittle stars" of relatively small size that live in rocks, sponges and / or corals, whose thin arms-rays appear to be fleecy. . These buffoons are the same "hitchhikers" I spoke about above; they get into aquariums with live stones, corals, etc. Therefore, if one day you find one (or several specimens) in your aquarium, do not worry. I have never seen them do any harm to what they live on, besides, they do not require any additional nutrition. They survive on their own and often even breed in captivity.

There are numerous species of "brittle stars" of small size, such as Ophiothrix spp.,
which get into our aquariums "hitchhiking" with corals, etc..
They are harmless and do not require any additional care.

It may seem strange that such invertebrates breed in aquariums, but I have repeatedly come across this. Most of the species are of separate sexes, although many are hermaphrodites, sometimes they breed in aquariums and the process covers the entire aquarium. 1,6 I have seen dozens of brittle stars simultaneously emerge from their hiding places in rocks etc., climb onto anything high they can climb, and then begin to release small clouds of gametes. Some may also carry their babies in special pockets on their bodies and release them into the water as miniature juveniles. 1,6 Many species are able to reproduce by fission (splitting), separating parts of their own body. In general, echinoderms are able to regenerate lost or damaged body parts; this ability to regenerate also allows them to produce more of their kind asexually. 1.7 So don't be surprised if you had one instance of a brittle star and then there are several. I'm pretty sure I've had several hundred small individuals in my large reef tank, and not a single one was deliberately introduced into the system.

I didn't manage to photograph gamete clouds, but I did manage to capture a couple of small "brittle stars"
climbing on corals and breeding.

With all that said, I would like to note that among all the ophiurs one should stay away from the "heads of the Gorgon". Gorgon heads catch fairly large zooplankton, including crustaceans and polychaetes, and aquariums usually lack (or lack of) suitable zooplankton.1 Therefore, these brittle stars are not suitable for captivity. Although I have come across them for sale from time to time, after a very careful search for information, I have not been able to find a single case of keeping a Gorgon head of any size alive for several months. Let's go further...

Finally, there are a couple more things to know about brittle stars/wyrmtails. First, you need to be very careful with the acclimatization of any brittle stars. I have found that they are usually very sensitive to changing conditions and take a long time to adapt to aquarium water. Acclimatization using the drip method seems to be the best option; the only thing you need is a small bucket and a piece of pipe. Dip the specimen in a bucket of water from the store, and then run the siphon from the aquarium into the bucket through a piece of tubing. To slow down the flow of water, simply tie a knot in the tube. Then, slowly mix the water coming from the aquarium with the water from the store until the water level in the bucket is four times the original (approximately). Then run the instance into the aquarium.

In addition, during the purchase process, carefully examine the copy for the presence of any white goo. If a specimen is not healthy, it becomes white and overly soft, so look out for any abnormalities. In my experience, it is extremely rare for them to recover from the onset of signs of illness, so specimens with any such signs should be discarded.

However, don't discard an instance with a missing ray (or two); if the instance is healthy, its limbs will quickly regenerate. The arms-rays can be lost in the process of catching, often ophiurs shed their rays as a way to avoid predators, just like lizards are able to shed part of their tail for the same purpose. Let me remind you again that echinoderms are famous for their ability to regenerate lost limbs; therefore, if there are no signs of decay and you can see a new growing ray, be sure it will continue to grow and, under good conditions, the animal will recover.

Echinoderms have very impressive regenerative abilities.
If you come across a specimen with a missing ray arm that is in the process of regeneration, don't worry.
Under good conditions in the aquarium, over time, the limb will grow to a normal size.