The
body of sea urchins are usually nearly spherical, ranging in size from
2-3 to 30 cm, covered with rows of calcareous plates. The
plates are usually connected to motionless and form a dense carapace
(shell), not allowing to change the shape of a hedgehog. The shape of the body (and some other features), sea urchins are divided into right and wrong. Have the right body shape urchins almost round, and they are built on strictly a five-way radial symmetry. At irregular urchins flattened body shape, and they are distinguishable front and rear ends of the body. With the shell of sea urchins adjustably connected (via joint capsule with the muscle fibers), needles of various lengths. The length varies from 1-2 mm (sand dollars,) up to 25-30 cm (diademovye hedgehogs). There
is a kind of, completely devoid of needles - toksopneustes (whose body
is covered with pedicellariae. Needles are often the sea urchins for the
movement, nutrition and protection. Some species are poisonous, as are
connected with a special poison glands. Venomous species (Asthenosoma,
Diadema) are common in mainly in tropical and subtropical regions of the Indian, Pacific and Atlantic oceans.In addition to needles on the surface of the shell of sea urchins sitting pedicellariae, as well as, the mouth opening, the special organs of balance - sferidii. Some species are poisonous pedicellariae of cancer.
Ambulacral system is common in echinoderms. Each tentacle leg, fitted with a suction cup, passes through a skeletal plate armor with two branches (through 2 pores). Podia the bottom of the sea urchins are used for movement and digging holes. Legs dorsal transformed into organs of touch and breath. In some species the ambulacral feet, along with needles and pedicellariae are actively involved in the process of purification of the shell and nutrition.
Rot
in sea urchins is located in the center of the lower (oral) side of the
body, anal and genital openings - usually in the center of the upper
(aboral) side. At
regular sea-urchin's mouth is provided with masticatory apparatus
(Aristotle lantern), which is used for soskrebyvaniya algae from the
rocks . Aristotle's lantern consists of five complex jaws, each of which terminates in a sharp tooth. Aristotle's
lantern teeth are involved not only in food processing, but also in the
movement (sinking into the ground), and presumably in digging burrows. In irregular sea urchins, which feed on detritus, the masticatory apparatus is not.
The intestine has no radial structure, as is the tube that runs from the mouth opening in a spiral inside the body cavity. Sometimes it goes along the subordinate intestine, opening into the intestine at both ends. Respiratory organs are the outer skin gills, located near the mouth, ambulacral system and subordinate intestine.
The sense organs and nervous system rather poorly developed. In addition to the tactile tentacle legs and sferidiev, the urchins are primitive eyes located on the upper side of the body. Widely distributed in the oceans and seas with normal saline to a depth of 7 km; absent in salted Caspian, Black and Baltic seas partially. Widely distributed on coral reefs and coastal waters, often selyas there in the crevices of rocks and depressions. Regular sea urchins prefer rocky surfaces; wrong - a soft and sandy soil.
Sea urchins - bottom crawling or burying animals. Moved with tentacle legs and needles. According to some assumptions, with the help of "Aristotle's lantern" sea urchins drilled a hole in the rocks, even the granite and basalt, which hide during low tide, and from predators. Other species are buried in the sand or simply cover themselves with pieces of shells, seaweed, etc.
Practically omnivorous. The diet consists of algae, sponges, bryozoans, ascidians, and a variety of carrion, as well as clams, sea stars, small and even other sea urchins. Purple hedgehog Sphaerechinus granularis easy to cope with cancer-mantis Squilla mantis. Living in the soft ground types swallow sand and silt, digesting the fall with them small organisms.
Some marine organisms use to protect the sea urchin, hiding among their needles sea cucumbers, brittle stars, polychaetes. Parasitic gastropods (Melanellidae), penetrating into the base of needles kopenosnyh urchins form galls and thus hinder the growth of the needle. Some species of mussels attached to their needles laying and developing shellfish shells drilled hedgehog, pushes him into the proboscis and feed on the tissues.
Sea urchins are food for lobsters, sea stars, fish, birds and sea lions. The main natural enemy of the sea urchin is a sea otter. Catching a hedgehog, otter, or turns it into a long legs (and sometimes pre-wrapped in seaweed) in order to crush a needle and then eat, or a hedgehog breaks stone on his own chest. The number of sea otters urchins eaten so great that the intestines, peritoneum, and even the bones of marine mammals sometimes colored pigments of sea urchins in a purple color.
Sea urchins dioecious, sometimes the males are slightly different in appearance from the females. The development of planktonic larvae (ehinoplyuteus), and some Antarctic species viviparous - the eggs develop under the protection of the needles on the upper side of the body or brood chamber, so that the young hedgehog leaves his mother full-fledged.
Maturity and reach commercial size sea urchins in the third year of life. According to estimates of annual rings on the plates of shells, sea urchins, the age average of 10-15 years, maximum - 35 years. At the same time, there is still an unconfirmed report that hedgehogs are found in the age of 200 years and possibly hedgehogs are immortal. Since hedgehogs are growing all his life, and their size is limited only by their age. Eternal life?, In the Red Sea urchins are found immortal
Many sea urchins are the target species. They are a traditional dish of the inhabitants of the coasts of the Mediterranean Sea, North and South America, New Zealand and Japan. Highly valued by their milk and eggs in particular, which contains up to 34.9% fat, and protein 19,2-20,3%. The shell is a good fertilizer for marginal land, as it contains plenty of calcium and phosphorus. In addition, the current research found that the pigment isolated from sea urchin (echinochrome), has strong antioxidant activity.
The intestine has no radial structure, as is the tube that runs from the mouth opening in a spiral inside the body cavity. Sometimes it goes along the subordinate intestine, opening into the intestine at both ends. Respiratory organs are the outer skin gills, located near the mouth, ambulacral system and subordinate intestine.
The sense organs and nervous system rather poorly developed. In addition to the tactile tentacle legs and sferidiev, the urchins are primitive eyes located on the upper side of the body. Widely distributed in the oceans and seas with normal saline to a depth of 7 km; absent in salted Caspian, Black and Baltic seas partially. Widely distributed on coral reefs and coastal waters, often selyas there in the crevices of rocks and depressions. Regular sea urchins prefer rocky surfaces; wrong - a soft and sandy soil.
Sea urchins - bottom crawling or burying animals. Moved with tentacle legs and needles. According to some assumptions, with the help of "Aristotle's lantern" sea urchins drilled a hole in the rocks, even the granite and basalt, which hide during low tide, and from predators. Other species are buried in the sand or simply cover themselves with pieces of shells, seaweed, etc.
Practically omnivorous. The diet consists of algae, sponges, bryozoans, ascidians, and a variety of carrion, as well as clams, sea stars, small and even other sea urchins. Purple hedgehog Sphaerechinus granularis easy to cope with cancer-mantis Squilla mantis. Living in the soft ground types swallow sand and silt, digesting the fall with them small organisms.
Some marine organisms use to protect the sea urchin, hiding among their needles sea cucumbers, brittle stars, polychaetes. Parasitic gastropods (Melanellidae), penetrating into the base of needles kopenosnyh urchins form galls and thus hinder the growth of the needle. Some species of mussels attached to their needles laying and developing shellfish shells drilled hedgehog, pushes him into the proboscis and feed on the tissues.
Sea urchins are food for lobsters, sea stars, fish, birds and sea lions. The main natural enemy of the sea urchin is a sea otter. Catching a hedgehog, otter, or turns it into a long legs (and sometimes pre-wrapped in seaweed) in order to crush a needle and then eat, or a hedgehog breaks stone on his own chest. The number of sea otters urchins eaten so great that the intestines, peritoneum, and even the bones of marine mammals sometimes colored pigments of sea urchins in a purple color.
Sea urchins dioecious, sometimes the males are slightly different in appearance from the females. The development of planktonic larvae (ehinoplyuteus), and some Antarctic species viviparous - the eggs develop under the protection of the needles on the upper side of the body or brood chamber, so that the young hedgehog leaves his mother full-fledged.
Maturity and reach commercial size sea urchins in the third year of life. According to estimates of annual rings on the plates of shells, sea urchins, the age average of 10-15 years, maximum - 35 years. At the same time, there is still an unconfirmed report that hedgehogs are found in the age of 200 years and possibly hedgehogs are immortal. Since hedgehogs are growing all his life, and their size is limited only by their age. Eternal life?, In the Red Sea urchins are found immortal
Many sea urchins are the target species. They are a traditional dish of the inhabitants of the coasts of the Mediterranean Sea, North and South America, New Zealand and Japan. Highly valued by their milk and eggs in particular, which contains up to 34.9% fat, and protein 19,2-20,3%. The shell is a good fertilizer for marginal land, as it contains plenty of calcium and phosphorus. In addition, the current research found that the pigment isolated from sea urchin (echinochrome), has strong antioxidant activity.
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