seahorses 2 - 2,000 living species of starfish that occur...

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2,000 living species of starfish that occur in all the world's oceans, including the Atlantic, Pacific, Indian as well as in the Arctic and the Southern Ocean (i.e., Antarctic) regions. They have bony, calcified skin, which protects them from most predators, and many wear striking colors that camouflage them or scare off potential attackers. They are purely marine animals, there are no freshwater sea stars, and only a few live in brackish water. These invertebrates are NOT fish; they are echinoderms . Echinoderms (Phylum Echinodermata) are a phylum of marine animals . Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone . Sea stars move very slowly along the seabed, using hundreds of tiny tube feet. Most species are dioecious , with separate male and female individuals, but some are hermaphrodites. For example, the common species Asterina gibbosa is protandric , with individuals being born male, but later changing into females. Male and female sea stars are not distinguishable from the outside; one needs to see the gonads or be lucky enough to catch them spawning. Change slide Sea stars are famous for their ability to regenerate limbs, and in some cases, entire bodies. They accomplish this by housing most or all of their vital organs in their arms. Some require the central body to be intact to regenerate, but a few species can grow an entirely new sea star just from a portion of a severed limb. Change slide Most starfish typically have five rays or arms, or a multiple of 5, which radiate from a central disk.
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This note was uploaded on 03/15/2012 for the course JOURNALISM 162 taught by Professor Shah during the Fall '11 term at University of Wisconsin.

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seahorses 2 - 2,000 living species of starfish that occur...

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