•Echinoderms are
__________, ________,
__________, ________,
____________,
_____________ and
____________.
* Echinoderm means
_______________. All
echinoderms have spiny skin.
They live in the ocean!
•There are ______ characteristics of
echinoderms.
•All echinoderms have:
• Spiny skin
• An internal skeleton (endoskeleton)
• Five-part radial symmetry
• A water vascular system
• Tube feet
* All echinoderms have
__________. Some of
them have small hair-like
spines, like the starfish.
* Some echinoderms
have long spines, like the
sea urchin.
* The internal skeleton of an echinoderm
is made of _______________________.
* An echinoderm’s water vascular system is
_________________________________.
* The water vascular system also helps an
echinoderm _____.
* The system opens to the outside
through the sieve like madreporite.
Madreporite
•Opening to the outside
•Connects to a ring canal
around the mouth
•5 radial canal extend up the
arms from the ring canal
* Echinoderms have __________.
* An echinoderm’s tube feet are used for
_________________________________.
*Five-part radial symmetry.
*They have no anterior or posterior end and
lack ______________.
* But the bodies are 2-sided. Mouth side
is the oral surface & the opposite side is
the aboral surface.
Plan for
the Day
•Review unifying characteristics of
Echinoderms
•Examine 5 classes of the Phylum
Echinodermata
•Check your understanding activity
•* Mollusc & Echinoderm test WEDNESDAY
5 Classes of
Echinoderms
•Asteroidea
•Echinoidea
•Ophiuroidea
•Holothuroidea
•Crinoidea
* A sea star is able to
re-grow its arms
* Carnivores: use tube
feet to move and to
open bivalves to eat
Class
Echinoidea
Sea urchins & sand dollars
* Have solid plates surrounding their
internal organs
*Most are detritivores or grazers.
* Sea urchins have longer and sharper
________ that they use to protect
themselves.
* Sea urchins have a mouth hidden under
its body and they eat sea algae (kelp).
* A sea urchin is not very active. Sometimes, it
does move slowly using its __________. When
not moving it uses its feet to stick to the ocean
floor.
Class Ophiuroidea
Brittle Stars
* Have slim, flexible arms, and can move
quickly. Can detach an arm if being attacked!
* Filter feeders and detritivores that come
out at night
Class Holothuroidea
Sea cucumbers
* Feed on detritus
* Can expel all their internal organs as a
decoy if being attacked!
Class Crinoidea
& feather stars
Sea lilies
* Oldest echinoderms
* Filter feeders: attach to the seafloor by a
stock and use their tube feet to catch prey
Echinoderms: Form &
Function
Feeding
Respiration
Circulation
Excretion
Response
Movement
Reproduction
Feeding
Sea urchins: five-part jaw to eat
algae
Sea lilies: tube-feet to trap plankton
Sea cucumbers: eat sand &
detritus on the ocean floor or
filter feed
Sea stars: tube-feet to pry open mollusks
shells. Evert their stomach into the mollusk
shell and secretes digestive enzymes. Brings
stomach and digested food back inside.
(digests externally)
Respiration & Circulation
**Water vascular system** - primary system
•Carries oxygen, food and wastes
*Tube-feet allow some diffusion through thin
walls for respiration (gas exchange)
*Skin gills are present in some echinoderms
for gas exchange
*Sea cucumber: pumps water in and out of its
anus to provide oxygen to its respiratory
trees
Excretion
Nitrogen-containing wastes are excreted
through thin-walled tube feet
Digestive wastes (feces) are released
through the anus
Response
Primitive nervous
system (no brain)
Nerve ring surrounding
the mouth connects to
radial nerves to the
body segments
Senses: to detect light,
gravity and chemicals
Movement
Tube feet ! – All use tube feet to move
(water-vascular system) - hydraulics
Sand dollars & sea urchins move their spines
Sea stars & brittle stars move arms because
of flexible joints
Sea cucumbers move using muscular wall &
tube feet
Reproduction
External fertilization
•Eggs produced in
ovaries & sperm
produced in testes
•Gametes released
into the water for
fertilization
•Larvae are free
swimming
Reproduction
Regeneration
Sea stars can
regenerate: must
contain part of the
centre ring
Echinoderm Ecology
Urchin Barren: created by
overpopulation of urchins
Sea stars are predators and
help control the growth of
mollusks (mussels) & corals
Echinoderm Ecology
Threat to coral reefs: sea star
called crown-of-thorns
Feeds on coral and has destroyed
coral reefs in Australia
Review Questions
.