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Echinoderms |
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| This animal phylum of Echinodermata
is an old one, reaching back some 600 million years
and is a sister group to our own phylum of vertebrates.
The group includes some 6500 living species and
they possess a few very distinct characteristics which
set it apart from other animals. The most obvious one is
their radial body symmetry although they start
out as bilateral larvae and acquire that trait only in
the adult state. Another unique feature are their
tiny tube feet used in food gathering and movement.
They also do without any apparent brain or head for that
matter, having a system of radial nerves. All species
inhabit in seawater and are bottom dwellers. |
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SEA STARS
| are also often called
starfish and make up the order of Asteroidea. They
possess a central disc with five (or sometimes more)
arms radiating from it and reside on the sea bottom.
Some are particle feeders but others prey or scavenge on
molluscs, crabs, worms and even other echinoderms. |
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Blue Sea Star |
Pyramid Sea Star |
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Panamic Cushion
Star |
Panamic Cushion
Star |
Chocolate Chip
Sea Star |
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SEA URCHINS
| are protected by spines
(in some species like the hatpin poisonous) in various
degrees and move around on tiny tube feet. They are
mostly herbivores feeding on algae or plants. Green sea
urchins often cover themselves (see below) with shells,
small pieces of rocks or algae. |
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Green Sea Urchins |
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Hatpin Urchin |
Slate Pencil Urchin |
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SEA CUCUMBERS
| are bilateral built and
cover themselves often with bottom sand and particles
(see below) to hide their colored bodies. They are
mostly plankton feeder and and many have toxin for
protection against predators. They are threatened as
many are taken for the Asian market where they are
considered a delicatessen. |
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Holothuria Sea Cucumber |
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