They live both in shallow water and in depths as great as 6,000 meters. 5. Most of the fish have low metabolism rate as the zone lacks in nutrients. But its takes a while.

Sans Central Disc .

Sea stars accomplish this by housing most or all of their vital organs in their arms, which means some species can even regenerate an entirely new sea star from just one arm and a portion of the star's central disc. 5. They cannot survive in fresh water. There are three categorized sea stars, which are Phanerozonia, Spinulosa and Forcipulata. They can regenerate. While many species live in tropical areas, you can also find sea stars in the cold waters of the Earth, even the polar regions. Most species of sea stars must split part of their central disc along with a limb for regeneration to occur. There are around 2,000 species of sea star. Sea urchins are generally nocturnal, during the day they hide in crevices. But it was the species known as Pisaster ochraceus, the ochre star, that took the brunt of the damage. Sea Star, sea star, also called starfish, echinoderm of the class Asteroidae, common in tide pools. Increased numbers of sea stars can damage coral reefs and commercial oyster beds. Many species of sea stars are considered keystone species within their environments. Pisaster ochraceus and at least 20 other species of sea star have been affected. There are more than 2000 species of sea stars and they lives in a various different place throughout the world’s marine, from inter tidal rock pools to the deep seafloors. People are most familiar with the common five-armed varieties, but some species have up to 40 arms. In other species of sea stars (Allostichaster polyplax and Coscinasterias calamaria) the body is broken into unequal parts (= fission) then the missing limbs regenerate. Keystone species - Sea stars; Free. They are found free-ranging worldwide in marine environments; over and under rocky, sandy and muddy sea bottoms. Feather stars or comatulids refer to the unstalked forms. It is the largest sea star in terms of arm span, reaching nearly 40 inches from arm tip to arm tip, and is also the heaviest, weighing in at up to 11 pounds. Sea stars vary in size from under 1/2 in. They usually have five arms. Did You Know? Brittle stars (Ophiuroidea) are a group of echinoderms that resemble starfish. Sea lilies and feather stars are examples of Crinoidea. Sea star wasting … Sea Urchins Reproduction: Locomotion by tube feet but also by movement of the spines on the underside of the body. Photo credit: wikipedia.com. The largest known starfish, the sunflower star (Pycnopodia helianthoides), manages to break several records. There is a group of less common species that have more than five! There are around 2,000 species of sea star.