Sea urchins message briefly. Sea urchin

In maritime and ocean depths Ah, there are many beautiful and interesting animals. One of the most mysterious representatives of the deep ichthyofauna is the sea urchin. Man knows more than 900 species of these echinoderm creatures, which can differ not only in appearance, but also in their way of life.

Today, science knows more than 900 species of sea urchins.

Habitats of echinoderms

Sea urchins live only in warm waters with a high level of salinity and are never found in fresh water. The bottom of all oceans is inhabited various types these animals. The most numerous populations live:

• in the Indian Ocean;
• in the Caribbean;
• on east coast Australia, washed by the Pacific Ocean;
• in the waters Hawaiian Islands.

Colonies of echinoderms can be found both at shallow depths in the area of ​​underwater rocks and on deep sea reefs. In shallow sea bays, as a rule, there are “spines” with a spherical body shape.

Flat-bodied species live at deeper depths. These creatures have never been seen in the basins of the Black and Caspian Seas, since the salinity level of the water in these reservoirs is extremely low.

In the Baltic Sea, individual echinoderms are occasionally found. Since some species of sea urchins live at depths of over 6 thousand meters, much about their lifestyle remains a mystery.

Body structure

Most people associate a sea urchin with a creature that has huge number sharp thorns, which is not entirely true. Some species of these creatures do not have spines at all and pose absolutely no danger to humans. There are varieties whose body is covered with mass small needles, which are not only incapable of injuring a person, but also make the sea creature very pleasant to the touch.

Some species of sea urchins do not have spines at all and pose no danger to humans.

Sea urchins are the oldest animals that appeared on earth more than 500 million years ago. Their closest relatives include no less ancient creatures - starfish. Sea urchins can be roughly divided into 2 large groups- right and wrong. These groups include 4 more superorders, consisting of 9 orders. This diversity of classification suggests that the World Ocean is inhabited by great multitude various types sea ​​urchins, differing in a number of characteristics:

• body shape;
• the structure of the body;
• color;
• way of life.

Unlike the starfish, the hedgehog has no prominent rays on its body, and the animal itself has the shape of a flat disk or ball. The group of irregular hedgehogs includes creatures that are egg- or heart-shaped. Since the animal’s body is enclosed in a durable shell consisting of several plates, its shape remains unchanged throughout its life.

The closest relatives of sea urchins include starfish.

The structure of the shell is always the same. It consists of plates located along the meridians of the body. The mouth opening is located on the abdomen and always faces the bottom. On the opposite side is the anus. Near the mouth opening there are external gills and spheridia - organs responsible for balance.

In the depths of the mouth there is a chewing apparatus, consisting of several plates connected by muscles. The basis oral apparatus- 5 paired pyramids in which the teeth are located. Using its teeth, the animal scrapes algae from hard surfaces and captures a variety of food.

From the mouth to the anus there are ambulacral plates, each of which has several paired holes. The legs pass through these holes.

The number of tiny legs on the body of one animal can be in the hundreds. Without exaggeration, we can say that sea urchins are the most multi-legged creatures on earth.

Appearance

The legs are very elastic; they can stretch and contract. At their ends there are suction cups, thanks to which the hedgehog can move not only in the horizontal plane, but also climb sheer cliffs. Suction cups help to securely attach to the bottom soil and obtain food even in places of strong surf.

Each of the rows of ambulacral plates ends with a small orbital plate on which the eye is located. Thus, it turns out that the organs of vision of these creatures are located throughout the body.

On the surface of the shell there are numerous tubercles to which needles are attached. Thanks to the movable muscle joint, the hedgehog can turn its spines in different directions. Needles can vary in shape and length and have different textures:

• smooth;
• ribbed;
• with spines and shoots.

On the surface of the sea urchin's shell there are numerous tubercles to which spines are attached.

The needles are used not only for protection from potential enemies, but also for moving along the bottom. Among the needles are prehensile organs, which are tiny tweezers attached to the plates using muscle connections. In some species of hedgehogs, the grasping organs are equipped with poisonous heads. Sea urchin venom is highly toxic and even dissolved in water poisonous substance capable of providing damaging effect on sea life. The main purpose of the poisonous heads is protection from sea predators.

The coloring of sea urchins can include the entire color palette. Some species can change color depending on the color of the soil and lighting.

Nutritional nature

Representatives belonging to the wrong subclass mainly feed on small plankton. The diet of proper hedgehogs is more varied. Proper sea urchins eat:

• a variety of algae;
• ascidians;
• bryozoans;
• sponges;
• various carrion.

Cases of cannibalism are not uncommon among some species of sea urchins.

Large individuals can switch to feeding starfish small size. Cases of cannibalism are not uncommon among some species. The most major representatives of this family, such as Strongylocentrotus, are able to catch and eat mantis crabs. Species that live on sandy soil or other soft substrates swallow bottom soil along with the microscopic organisms living in it. If there is no food in the area of ​​the reservoir where sea urchins live, they can make significant migrations in search of food.

Varieties of underwater urchins

In nature, there are more than 900 species of animals belonging to this class. Some species are quite widely represented, while others are extremely rare. The most common ones include:

• black sea urchin;
• round;
• Japanese;
• slate;
• diadem.

The black sea urchin looks the most menacing, as it has some of the longest spines, which pose a considerable danger to humans. When danger arises, the animal immediately points its weapon to the side probable enemy and behaves very aggressively.

Round view- one of the most common, also having impressive size needles that can seriously injure a person. Japanese view lives in the sea with the same name and is a staple dish in Japanese restaurants. Slate - distinguished by its bright red color and triangular shape of needles, which do not have sharp ends and are therefore completely safe.

The type of tiara represents increased danger for a person, since he likes to settle near Turkish resort beaches. The needles of this species are very fragile, and if a person was careless to step on such a creature, then in the future he will have to undergo a painful procedure to remove the needles that have penetrated the skin.

Sea urchins play an important role in the ecosystem because they are able to absorb carbon dioxide, thereby reducing its amount in the atmosphere. The entrails of these animals have been used for the manufacture of various medicines since ancient times.

Sea urchin. The seas and oceans are inhabited from the very surface to the deepest depressions, and everywhere you can see how the most amazingly animals are adapted to different conditions and forms of existence. Life exists in the dark, cold depths of the ocean, and in the upper warm water layer, and in the crevices of coral reefs, and under the thick ice of the Arctic, and along the coast of Antarctica.

But the plants are not at all the ones we are used to seeing on land. The bulk of animals in the ocean are a variety of protozoa: sponges, sea urchins, etc. Today we will talk about sea urchins, whose needles are the same prickly as those of the land ones that are familiar to us. These animals appeared on Earth 500 million years ago. To date, about 950 species of echinoderms are known. Usually sea ​​urchins They have the shape of a flattened ball, but can also have the shape of an egg, a bottle, or even a heart. The body is covered with needles of the most various forms– smooth, ribbed, with spines, processes up to 30 cm long. Sea urchins need needles not only for protection, but also for movement. With their help, animals can reach speeds of up to 2 m/sec.

Among sea ​​urchins there is also poisonous species. With the injection of their needles, poison enters the animal’s bloodstream, so strong that it can cause paralysis. Japanese fishermen call such sea urchins killers.

The skeleton-shell of a sea urchin consists of 20 flattened and fused plates. The mouth opening contains 25 partitions and plates, which are called the “Aristotelian lantern”. This is the chewing organ sea ​​urchin. It feeds on algae, but on occasion it will not disdain food of animal origin.

Sea urchins, like all representatives of the echinoderm class, are inhabitants of the sea and ocean depths. Most often they settle at a depth of up to 7 kilometers. The most important criterion for the residence of sea urchins is the salinity of the water; they are not found in low-salinity seas (Black Sea, Caspian Sea and part Baltic Sea). A large number of sea urchins live on coral reefs. The main part of coral reefs is located in the Indian and Pacific Ocean. Urchins are also often found in coastal waters.

Very poisonous species of sea urchins live in the waters of the Atlantic, Pacific and Indian Oceans. A person who pricks himself with a sea urchin gets a large number of poison, which can cause paralysis and ultimately death.

Sea urchin habitats

Most sea urchins prefer to live on rocky surfaces. Easily climbing any rocks with the help of their needles and ambulacral legs, hedgehogs seek refuge in them in the form of depressions. If there is no suitable shelter, then the hedgehogs drill it themselves.

Among these inhabitants there are also exceptions that settle on sandy or soft ground. To hide from predators or wait out big waves, such hedgehogs hide in the sand or cover themselves with shells, algae, stones and other other objects. In addition, small food particles found in squeak or sludge.

Sea urchins are inhabitants of the World Ocean. These representatives of the ichthyofauna can be dangerous to humans. At the same time, they provide great benefits. About the types of these animals, their appearance, reproduction and nutrition, read this article.

Kinds

The class of these echinoderms is very numerous. Therefore, animals belonging to it are conventionally divided into two subclasses. First group - correct hedgehogs, that is, those whose body shape is spherical. The body of irregular echinoderms is more like a stretched disc.

There are more than 900 species of animals, some of which are very common. These include:

• Black sea urchins that have long needles. This animal represents great danger for humans, as it has long needles. An interesting fact is that the beauty of a black hedgehog can quickly turn into its weapon: at any sign of danger, it directs its needles towards the irritant. That is, a shadow from any object falling on him can be regarded as an attack.
• A round sea urchin that can also be dangerous to humans. It is one of the most common types.
• Japanese sea urchin. The name tells you where it lives. This representative of echinoderms can attack a person if it senses danger emanating from it.
• Slate sea urchin, which is distinguished by its amazing red color. Its needles have unusual shape triangle with a blunt apex. According to one version, it got its name due to the fact that in ancient times they used its needles to write on
• A species such as a diadem is very dangerous for humans. At the slightest sign danger animal pierces with fragile needles skin covering sacrifices and they break. The process of removing them is very painful. This species is often found near favorite among tourists Turkish coasts.

Description

Animals about we're talking about in this article, belong to the class echinoderms. Most often, sea urchins have a spherical body, the diameter of which ranges from 2 to 30 cm, including spines. On one side it is wrinkled, as the mouth opening is located there. Moreover, it is this part of their body that serves as a means of transportation, because with its help animals move along the seabed. The skeleton of these echinoderms is very well developed; it is soft only near the mouth and anus, located on the back. With the help of numerous tubercles covering the surface of the body, needles are attached to it.

The sea urchin, described in this article, can have almost any color. Some species have unique ability adjust body color to the surrounding space.

Needles

Lime sticks have a cylindrical shape. They are movably attached to the body, which allows them to easily rotate in different directions. They not only protect animals, but also help them move. Moreover, some of them have a grasping function. In this case, it is customary to call these organs pedicellariae.

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Sea urchins can fatally poison humans. How does this happen? As soon as the animal feels that it is in danger, it slams its needle-tweezers on the body of the victim and injects poison under the skin. It is a whitish liquid.

The places that were pierced begin to itch. A person feels a strong burning sensation, his skin acquires a pronounced red tint, and swelling may form. All this is accompanied by pain. In severe cases, loss of sensation occurs and the victim may be paralyzed. The poison released by the tweezer needles infects nervous system. Under its influence, breathing is impaired, and this can be very dangerous for divers.

If you do not get to land in time and provide help to a person, he may die. Indeed, there are documented cases where a person struck by poison did not have time to rise to the surface and died. IN best case scenario the pain will go away in 20 minutes. In less than a week, other signs of poisoning will disappear. However, the paralysis effect lasts for 6 hours.

Habitats

All species of sea urchins live in waters that are of medium to high salinity. For example, the range of black urchins spans from Japan and China to East Africa. They can also be found near the Hawaiian Islands. The round hedgehog, as well as other representatives of the echinoderm class, have a similar habitat. These animals are not found in the slightly salty waters of the Black and Caspian Seas.

The favorite habitat of echinoderms is the seabed. They move along it with the help of ambulacral legs. These organs are long processes with suckers at the end. They also allow animals to move along vertical surfaces.

Nutrition

It's time to find out what the sea urchin eats. It all depends on which subclass of echinoderms it belongs to. Irregular hedgehogs consume plankton as food. But the diet of their correct relatives is more varied. Thus, these predatory animals are able to hunt crustaceans and mollusks. At the same time, they can eat algae and even carrion. They often attack other hedgehogs that are smaller in size, and also attack starfish.

Reproduction

To understand how sea urchins reproduce, you need to know a few facts about them. So, these animals are dioecious, that is, among them there are both female and male individuals. Fertilization is external. This means that the male fertilizes the eggs laid by the female. This happens in shallow water. However, those species that live in Antarctic waters are viviparous. In the female's body there is a special brood chamber, in which the development of eggs occurs.

Reproduction of sea urchins is a fairly simple process that most often occurs outside the female's body. However, those individuals that were born in Antarctic waters leave the mother's body fully formed. After three years, they reach sexual maturity. In total, the lifespan of these echinoderms ranges from 12 to 15 years. Cases have been documented when scientists were able to find individuals whose age reached 35 years. Therefore, they are conventionally considered long-livers.

Enemies

Despite the fact that sea urchins have good self-defense, they often become food for other birds, fish and mammals. For the otter, these echinoderms are a special delicacy. The animal catches the prickly ball, and then throws it several times onto a hard surface and breaks the shell. Seabirds hunt urchins in a similar way. So, large birds They lift their prey to great heights and throw the prickly food onto the rocks. The shell breaks and the meat of the animal remains unprotected.

Benefit

The sea urchin, the photo of which is presented in this article, is very valuable. Firstly, caviar of such types as fawn, multi-spined and green is very popular. According to Japanese beliefs, this product can prolong youth and give a person longevity. Indeed, caviar contains nutrients, essential amino acids and fats. Recently, studies were carried out, as a result of which scientists found that the genomes of humans and sea urchins partially coincide. That is why long-living animals can preserve the lifespan of Homo sapiens. It will be most beneficial to eat fresh caviar that has not been subjected to heat treatment. Not everyone likes it in its pure form, but it gives salads and other dishes an interesting taste.

Secondly, with the help of these animals you can catch commercial fish. The fact is that echinoderms gather in large groups during the spawning period. They attract fish and crustaceans that don't mind eating sea urchins. And at this time fishermen catch, for example, flounder.

The sea urchin forms a class belonging to the phylum Echinodermata. There are more than 900 species in the class. They are divided into two large groups or subclasses: regular hedgehogs and irregular ones. The former have a round body shape, while the latter are like stretched discs, that is, they have front and back parts of the body. These animals live in sea ​​water at a depth of no more than 5 thousand meters. The water should have normal salinity. For example, the Caspian and Black Seas are lightly salted, so sea urchins are not found in these waters.

These representatives live marine fauna at the bottom. They move with the help of special ambulacral legs. There are several hundred of them. The legs are long elastic processes. They have suction cups at the ends, so sea ​​creature can crawl not only on horizontal, but also vertical surfaces.

An Aristotelian lantern also helps the hedgehog move. This is an oral chewing apparatus, found only in representatives of the correct subclass. On the outside it is marked by the tips of 5 long teeth. The structure of this organ is very complex, and it functions with the help of powerful muscles. They are the ones who control the work of teeth. With their help, the sea urchin scrapes off food located on the ground. This is the most diverse deep-sea vegetation. In addition, teeth grind food.

The muscles of the Aristotelian lantern are so strong that the animal can move along the ground, relying on its teeth. With the help of this device, the marine inhabitant destroys hard surfaces and digs holes for itself in granite rocks. They provide excellent shelter from a wide variety of predators. Representatives of the wrong subclass usually bury themselves in the sand or hide among algae.

Appearance

The body shape of sea urchins is spherical. The usual size is 6-12 cm. There are babies with sizes 2-3 cm. The most large views reach 36 cm in diameter. Body color matches all the colors of the rainbow. In some species, the color can adapt to the color of the soil. But the shape of the body is always constant, since it is covered with armored plates. They are rigidly connected to each other and serve reliable protection from external damage. There are no plates only near the mouth and anus.

One part of the animal’s body is always facing the seabed, in the center of which is the mouth. On opposite side the anus is located. This is like the opposite pole, called aboral. Between them along the meridians there are rows of protective ambulacral plates. There are several dozen of them in each row. The plates have small holes through which the legs come out.

At the aboral pole, each plate is equipped with a small eye. And next to it is a larger plate. It contains sex cell. These plates surround the anus and make up the so-called apical field. And near the mouth opening there are gills. The animal's shell is dotted with numerous tubercles. Needles are attached to them through a special joint capsule equipped with very strong muscles. Thanks to them, the hedgehog can turn its needles in a variety of directions. The length of the needles reaches 1-3 cm, and the thickness is 1-2 mm. They are not very spicy.

Come across individual species with needles ranging from 10 to 30 cm in length. These natural spines help to move and protect during attack. Some species have poisonous needles. The sea urchin breathes using gills. The senses are very primitive. The irregular subclass does not have a chewing apparatus, since plankton predominates in the diet.

Reproduction and lifespan

Representatives of this class are dioecious. Females lay eggs in shallow water, and males fertilize them with their reproductive secretions. Some species living in Antarctic regions are viviparous. These individuals develop eggs in the brood chambers. A born hedgehog leaves its mother fully formed. Puberty occurs at the age of 3 years. Average duration life is 12-15 years. Centenarians can live up to 35 years.

Nutrition

Representatives of the subclass irregular hedgehogs, as already mentioned, feed on plankton. But the right hedgehogs have the most varied diet. They consume mollusks, small crustaceans, various seaweed, plant and animal carrion. They also eat smaller classmates and starfish.

Enemies

At first glance, the sea urchin is well protected. But still he becomes prey big fish, birds and mammals. The sea otter loves to feast on the meat of this animal. She takes the hedgehog with her paws, throws it onto the coastal rocks and breaks the protective shell. Birds do the same. A large feathered predator grabs a hedgehog with its beak during low tide, rises high into the air and throws its prey onto the rocks. The soft pieces of the body are then pecked out.

Danger to humans

Some species of sea urchins have long, thin spines. If you step on them in water, you can get a serious foot injury. The matter is aggravated by the fact that the needle breaks when piercing the skin. The tip remains in the person's leg. If, in addition, the needle is poisonous, then the pain can be very severe and long-lasting. Some poisons can cause muscle paralysis, as well as disruption of the heart and breathing.

When providing assistance to a victim, the first thing to do is remove the needle fragments from under the skin and treat the wound with an antiseptic. After this, it is necessary to take the victim to the nearest medical center so that he can receive qualified assistance. It is possible that the victim may have problems with breathing or the cardiovascular system. In this case, artificial respiration and sometimes cardiac massage are necessary. The most poisonous hedgehogs live in tropical and subtropical waters.