2. Echinoderms
The spiny misfits

3. General Characteristics
Larvae have bilateral and adults have radial symmetry
No head!
Endoskeleton- calcium carbonate

4. Water vascular system
Pattern of development in embryos is more similar to vertebrates

5. General Characteristics
Number of arms is in multiples of 5
Separate sexes
Nerve ring
Open circulatory system
Body cavity

6. Body
Most are carnivorous with a complete digestive tract
Nervous system is simple looking but these orgs have complex behavior
Regeneration is highly developed

7. Network of water filled canals
Water Vascular System
Network of water filled canals
Connects to the outside by a pore called the madreporite

8. Tube feet extend when filled with water thru canals
Used for locomotion and attachment

9. CLASSES OF ECHINOS Asteroidea Echinoidea Holothuroidea Ophiuroidea
Crinoidea

10. Slow moving, flexible arms
Asteroidea- sea stars
Slow moving, flexible arms
Predators of bivalves, snails, barnacles (slow-moving or attached animals)
Feed by everting stomach thru mouth

11. Echinoidea- sea urchins, sand dollars
Round hard endoskeleton with movable spines
Graze on sea weed and sea grasses as well as scavenge
Aristotle’s lantern- special mouth and jaw parts

13. Holothuroidea- sea cucumbers
Worm like
Deposit feeders
Interesting defense mechanisms
Secrete toxins
Discharge mucus and toxins thru their anus
Eviscerate guts thru mouth or anus
(they’ll grow back)

14. Ophiuroidea- brittle stars
Arms very flexible and can move quickly
Deposit feeders
Largest group of echinos but stay hidden

15. Crinoidea- feather stars and sea lilies
Suspension feeders with feathery arms for feeding
Deep water and either attached to the bottom or crawl