Echinoderms Phylum Echinodermata
Include sea stars, sea urchins, sea cucumbers
Have radial symmetry based on 5 parts (similar parts surrounding central axis) Planktonic larvae has bilateral symmetry Considered to have oral/aboral sides, NOT dorsal/ventral
Body Structure Have a water vascular system-water filled canals Tube feet-muscular extensions of these canals usually end in suckers used for attachment & locomotion
Ampullae-muscular sacs that sometimes fill tube feet with water Madreporite-connects vascular system to outside on aboral (top) surface Also has gonads & digestive system No heart, brain or eyes
Complete digestive tract-stomach, digestive gland & anus Endoskeleton-covered by a thin layer of tissue Surface covered with bumps & spines giving them their name-”spiny skinned” (echinodermata)
Five classes 1)sea stars 2)brittle stars Class: Asteroidea Subclass:Ophiuroidea
3)sea urchins & sand dollars Class: Echinoidea 4)sea cucumbers Class: Holothuroidea 3)sea urchins & sand dollars Class: Echinoidea http://www.youtube.com/watch?v=iSA09qg2BMY&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
5)feather stars & sea lilies Crinoidea
Sea stars (starfish) 5 arms to 50 Most are predatory- bivalves, snails, barnacle, etc.
Sunflower Star http://www.youtube.com/watch?v=ALaMoS_vvNE&safety_mode=true&persist_safety_mode=1&safe=active
Cushion Star
Brittle Stars Arms very long & flexible -tube feet lack suckers Eat particles of organic matter passed from feet to mouth More species than any other group of echinoderms
Basket Star (Brittle Star)
Brittle Stars
Sea Urchins & Sand Dollars Filter feed on drifting plant/animals Deposit feeders that live on bottoms using tube feet lined with mucus to pick up particles
Sea Urchins
Sand Dollars
Sea Cucumbers Wormlike, lack spines Tube feet around mouth reach out and pick up organic material Escapes by ejecting digestive system distracting predators
http://www. youtube. com/watch http://www.youtube.com/watch?v=aCxKFc3XtJs&safety_mode=true&persist_safety_mode=1&safe=active http://video.nationalgeographic.com/video/kids/animals-pets-kids/invertebrates-kids/sea-cucumber-kids/ Sea Cucumber
Feather stars & Sea lilies 5 to 200 arms due to the branching Mucus helps in catching food Some attach to bottom, some crawl on surfaces in shallow to deep water
Sea Lilies (with Stalks) Feather Stars (no Stalks http://www.youtube.com/watch?v=7V_px48dob8&safety_mode=true&persist_safety_mode=1&safe=active Sea Lilies (with Stalks)
Biology Sexes are separate in most echinoderms External fertilization Spawning occurs at once to increase survival
Echinoderms can use regeneration to replace missing parts In some sea stars a severed arm can grow into a complete individual http://www.youtube.com/watch?v=rE8l-KFQlhY&safety_mode=true&persist_safety_mode=1&safe=active