Sea stars are marine invertebrates belonging to the class of echinoderms. Its name starfish received thanks to its original form: they have from 5 to 40 limbs (rays). Starfish is 8 units and more than 1500 species and live mainly on the seabed, from the intertidal zone to a depth of 10 kilometers. Fresh water sea stars do not like.
Their diameter varies from 1 centimeter to 1 meter. The upper part of the starfish is called superalloy. It is covered with lime lumps, needles and short spikes, and also has small bodies, which are sometimes equipped with poison glands. In the centre superalloy side is the anus.
In the center of the bottom (oral) side of the starfish is the oral aperture. Each beam starfish with oral side has a groove. The grooves are ambulacraria legs, through which the sea star moves. Ambulacraria legs is flexible tubular outgrowths with suckers on the end. Their actuates the water pressure in the associated internal channels and sealed ambulacral system. Starfish is a very mobile animals, but they can only crawl along the bottom, but they can't swim.
These animals are predators. Eat stars clams and a variety of benthic invertebrates. The process of feeding sea stars very peculiar! Star bows shell clam hands-rays, stick to it ambulacraria legs and force pushes her sash. The stomach of stars turned out on the soft part of the mollusk, envelops and digests them without swallowing. Then liquefied and almost digested food moves into the body.
Sea stars well developed regeneration: if to tear the star beam, it grows again (as the tail of a lizard). And there are species that have detached from the ray can grow a full star!
Live sea stars an average of 30 years.