Phylum Echinodermata
Spiny Skinned animals
Echinoderms– echin (spiny) and derma (skin)
GENERAL INFORMATION
Symmetry
Secondary Pentaradial Symmetry– the larvae
are bilateral and the adults are radial
Body Development
• Bilateral larvae
• Pentaradial adult.
Videos:
http://www.youtube.com/watch?v=A100m5EpfFI starfish
eating
http://www.youtube.com/watch?v=6IP_I6IVyJQ&feature=relat
ed starfish
http://www.youtube.com/watch?v=E1t-Dz4u4u0 brittle star
moving
Water Vascular System
Tube feet: used for feeding, moving,
breathing, and even reproduction
are extended by taking in water
http://www.youtube.com/watch?v=4IRFpKVtuU tube feet
The white
parts are where
the tube feet
were in this sea
urchin
(Sea Stars)
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Mostly eat clams and oysters or other animal that is too slow to defend
itself
It slowly pries open its prey in order to eat it, sending out its stomach
to consume the body of the shellfish
They have two stomachs—one is used to eat and the other is used for
digestion
Unlike the brittle star, sea stars’ organs enter their arms.
They can break off their arms and the arms can regenerate
(Sea Cucumber)
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Sea cucumbers are scavengers, looking for food at the
bottom of the ocean
They usually live in tropical reefs
If it is threatened, it will stiffen and a jet of water will
shoot out of one end
If they feel threatened, they can also throw out their
internal organs (evisceration) to distract predators, then
grow new internal organs
Delicacy to eat in some countries
They use their tube feet to move very slowly
• sea cucumber evisceration
http://www.youtube.com/watch?v=a
CxKFc3XtJs&NR=1
• Sea cucumber lifestyle
• http://www.youtube.com/watch?v=vs
LBOkYLLeI
(Sea Urchin and Sand Dollars)
http://www.youtube.com
/watch?v=SRAfjvws13E
sand dollar moving
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Sand dollars become bleached and http://www.youtube.c
loose their spines when left out in
om/watch?v=4IRFthe sun on the beach, so the ones
in the store are very different from pKVtuU tube feet
live ones
Sea urchins have teeth made of
calcium carbonate, and the entire
chewing organ is called Aristotle's
Lantern
Sea urchins mainly eat algae, but
can also eat other invertebrates
like mussels, sponges, and brittle
stars
Feather Star
Sea Lily
• Sea lilies were once thought to be planted in the ground but
researchers found out that they actually can crawl from danger
at 5 cm/s. They use their leg-like “petals” to crawl along the
ocean floor. They use a lizard-like technique and leave their
roots behind when escaping predators.
http://www.umich.edu/news/index.html?Releases/2005/Oct05/crinoid
Brittle stars
• Long and nearly solid rays which move like snakes
• Arms can regenerate
• Carnivores, filter feeders, and scavengers
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Coelem is smaller than other
echinoderms