Starfish Bashny.Net

Sea stars are veterans of the seabed, they appeared more than 450 million years ago, ahead of many forms of the modern inhabitants of the underwater depths.
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They belong to the class of Echinoderms, being relatives of sea cucumbers, brittle stars, sea lilies, sea cucumbers, sea urchins, — currently there are about 1600 species have star-shaped or pentagonal shape. In starfish, despite its inactivity and the absence of the head itself, well developed nervous and digestive systems.
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And why, actually, "echinoderms"? The thing in the hard skin of the sea star is on the external side it is covered with short needles or spikes. Conventionally, these whimsical creatures can be divided into three groups: common sea stars, feather stars, called the twisting rays (up to 50!), and fragile stars, cast its rays in case of danger. However, for this animal is not difficult to grow a new one, and each beam will soon appear a new star.
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How is that possible? — Due to the characteristic features of the structure of stars — each of its rays have the same structure, and contains two digestive outgrowth of the stomach, performing the function of the liver red eye spot at the tip of the beam, protected by a ring of needles of the radial nerve bundles of the olfactory organs (they are the same suction cups and method of movement), located in the groove on the ventral side of the papule – skin gills in the form of fine short fibers, located on the back and producing gas exchange processes of genital organs (usually two gonads to each ray), the skeleton consisting of a longitudinal row of vertebrae in, and hundreds of calcareous plates with spines, covering the skin and connected with muscle that not only protects the animal from damage, but also makes her very flexible rays.
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The body of the starfish composed of 80% calcium carbonate.

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