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=