Http:

http://www.youtube.com/watch?v=Fo-gcZ78Ij0&mode=related&search=

EchinodermsThe spiny misfits

General Characteristics

• Larvae have bilateral and adults have radial symmetry

• No head!• Endoskeleton- calcium

carbonate

• Water vascular system

• Pattern of development in embryos is more similar to vertebrates

General Characteristics

• Number of arms is in multiples of 5

• Separate sexes• Nerve ring• Open circulatory system• Body cavity

Body• Most are carnivorous with a

complete digestive tract

• Nervous system is simple looking but these orgs have complex behavior

• Regeneration is highly developed

• Network of water filled canals

• Connects to the outside by a porecalled the madreporite

Water Vascular System

• Tube feet extend when filled with water thru canals

• Used for locomotion and attachment

CLASSES OF ECHINOS

Asteroidea

Ophiuroidea

Echinoidea

Holothuroidea

Crinoidea

Asteroidea- sea stars• Slow moving, flexible arms

• Predators of bivalves, snails, barnacles (slow-moving or attached animals)

• Feed by everting stomach thru mouth

http://www.youtube.com/watch?v=prCeHDa7GTQ

Ophiuroidea- brittle stars• Arms very flexible and can move

quickly

• Deposit feeders

• Largest group of echinos but stay hidden

http://www.youtube.com/watch?v=XV0KAr_M-7w&feature=related

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

http://www.youtube.com/watch?v=NdgyaRFgvQQ

http://www.youtube.com/watch?v=SRAfjvws13E

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)

http://www.youtube.com/watch?v=lKWSLg5PDiU

http://www.youtube.com/watch?v=vsLBOkYLLeI

Crinoidea- feather stars and sea lilies• Suspension

feeders with feathery arms for feeding

• Deep water and either attached to the bottom or crawl

http://www.youtube.com/watch?v=affSVrHHDfk&mode=related&search=http://www.youtube.com/watch?v=m7X6q-dfslQ&mode=related&search=