These majestic echinoderms are no longer called ‘starfish’
because they are not actually a fish. Their name has been changed to ‘sea star’.
There are 2000 species of sea stars. They are closely related to sand dollars
and sea urchins. Some live in tropical habitats while others live at the bottom
of the cold sea floor. Usually you will see a sea star with five arms. However,
there are some with ten, twenty, or even forty arms.
They have bony, fossilized skin which protects them from
predators. There are no sea stars that live in fresh water. Only few live in
brackish water. These creatures are well known to regenerate their limbs. It takes
approximately a year for this to occur. A lost arm can grow into a new sea star
if it has some part of the central ring included.
Sea stars do not have brains. Instead, they have nerves that
transmit messages to them. They do not have blood so they rely on water to pump
their legs. Sea stars eat mollusks, clams, coral, and dying fish. They eat
clams and other creatures with shells by opening their shell and inserting
their stomach to digest the critter. Some sea stars are poisonous like the crown
of thorns, the sun star, the spiny sun star and the leather star. What make these
poisonous are their spines. They have tiny suction cupped feet to help them
stick to objects. They breathe through these feet due to them having a water
vascular system.
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