Sometimes referred to as serpent stars and contains approximately 2000 species. Like starfish/sea stars, they have five arms radiating outwards from the central area. They differ only in that their arms are very thin and flexible. They prefer to hide under rocks during the day and search the bottom during nighttime to feed on organic matter/detritus. Even though most are not colorful, they are an excellent addition to well-established reef aquariums, especially those containing a well-established sandbed.
They have the same regenerative capabilities as do sea stars and can regenerate lost limbs. They differ from sea stars in that their tube feet serve a respiratory purpose only, not for locomotion purposes as they do with sea stars. Also, brittlestars only have a mouth, whereas starfish have both a mouth (on the bottom) and an anus on top.
Smooth armed species are usually referred to as serpent stars and those with spiny arms as brittle stars. I should also add that the taxonomy surrounding this order is somewhat confusing, and if you have something more defined, please contact me at saltcorner@cs.com.
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