Starfish move using a water-vascular system, which
depends on the hydraulics of moving muscles and
water about and making suction. Their water system
is open to the environment. As a result, they
cannot move out of water - and at low tide, their
food often is above the waterline.
Starfish, also known as "sea stars" are not
really fish at all.They don't swim. Instead, they
use tube feet with little suckers on the end to
walk around on rocks, sand and mud. They aren't
fast, but those tube feet can pull really hard.
For their size, they are very strong. One author
compared their pulling to that of a human lifting
a 1,000 pound weight with one hand. Their real
talent, though, is keeping up a steady pull for a
long time. Sea stars eat by crawling on top of
clam-like animals such as mussels, pulling their
shells apart, and eating the soft part of the
Many sea stars live
underwater all the time, so they're not affected
by tides much. Some do live in the inter-tidal
zone. When the tide comes in and the water covers
their prey, they go to work. When the tide is
low, they may stay in a pool waiting for the next
tide. Sea stars have to stay fairly wet. They
breathe through gills on their underside and they
use a hydraulic (water powered) system to move
their tube feet.You may see them out of the water
sometimes, but if they stay out too long, they
For some great pictures and
explanations of the tide pools around Santa
Barbara, go here.
pools have a high concentration of animals
compared to the open ocean. Why do you think so
many animals are found in the intertidal zone?
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