ECHINODERMATA
”Spiny Skin”
DAN FITZPATRICK &
ELIZABETH EZIRIKE
MAJOR CLASSES
ASTEROIDERA
OPHIUROIDEA
Star shaped, arms radiate around central disk
Distinct central disk, long brittle arms
ECHINOIDEA
CRINOIDEA
Spherical, no arms, 5 rows of tube feet,
mouth ringed
HOLOTHUROIDEA
5 rows of tube feet, tube feet surround
mouth act as feeding tentacles
Feathered arms surround mouth
suspension feeders
CONCENTRICCYCLOIDEA
Armless, disk shaped, incomplete DS
External Anatomy
Tube
Feet
Internal Anatomy: Starfish
Internal Anatomy: Sand Dollar
Internal Anatomy: Sea
Cucumber
Type Of Symmetry
Echinoderms have a combination of radial and
bilateral symmetry. The symmetry of the
larvae is bilateral, and the symmetry of the
adult is radial, although not truly.
Life Cycle
-Reproduction is sexual, through the use of
larvae
-Can reproduce asexually, through fission &
regeneration
Distinguishing Characteristics
 Water
Vascular System
 Tube Feet
 Mouth, but no head or
brain
INTERESTING FACTS
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Sea stars have two stomachs: a cardiac stomach that
helps them engulf food outside of their bodies and a
pyloric stomach.
Sea baskets and brittle stars can be predators and
can filter feed.
Echinoderms are found in oceans at all of the various
levels including the deepest ocean trenches. They are
not found on land or in freshwater.
Biologists believe that echinoderms can help discover
medicines that cause human disease. Some are used
for decoration and harvested as food.
ENDANGERMENT
Humans pose the most danger to
echinoderms and are responsible for
most of the population decline.
Over Harvesting
Pollution – Road
Pollution
Most still thrive today.
Bibliography
AP Edition Biology – Eighth Edition (Reese,
1998, Pearson/Benjamin Cummings)
 "Starfish, Sea Urchins and Other Echinoderms
- Spiny-skinned Animals." Te Ara Encyclopedia
of New Zealand. Web. 09 Feb. 2011.
<http://www.teara.govt.nz/en/starfish-seaurchins-and-other-echinoderms/1>.
 "Echinoderms." Acadia Oceanside Meadows
Historic Inn, Downeast Maine Bed and
Breakfast. Web. 09 Feb. 2011.
<http://www.oceaninn.com/the-naturepreserve/echinoderms/>.
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