Phylum:
Echinodermata
Characteristics
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“echino” = spiny
“derma” = skin
Spiny skin, internal skeleton, water
vascular system, tube feet and 5 part
radial symmetry
They are the most complex invertebrate
phylum because they have skin, an anus
and the larvae show bilateral symmetry.
Reproduction: Usually separate sexes.
External fertilization.
Water Vascular System – a system of
internal tubes which aid in respiration,
circulation and movement.
5 main groups of Echinoderms
1. Sea Urchins/Sand dollars
 large internal plates that form a box
around internal organs
Live sand
dollar
Dead sand
dollar
Sea Urchin
2. Brittle Stars
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Will shed an arm if attacked. Filter
feeders and detritivores.
3. Sea Cucumbers
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warty, moving, pickles. May eviscerate
(vomit) up part of intestines/stomach if
threatened.
4. Sea Stars
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carnivores, can
regenerate as long as
central ring is present.
5. Sea Lilies/Feather Stars
Sea lily
Feather star