Transcript Echinoderms
What kind of fish swims in the sky at night? Starfish Echinoderms Phylum Echinodermata “Spiny skin” • All Marine • CaCO3 in skin and shell (test) bumpy skin • Papilla increase surface area, breathe through skin • Secondary radial symmetry • Planktonic larva are bilaterally symmetrical • Radial symmetry is pentamerous (5 sided) (no anterior/ posterior, dorsal, or ventral but oral vs.. aboral). • Endoskeleton (sea urchin test) • Unique water vascular system, muscles squeeze water into and out of tube feet, which, ends in suckers for attachment and movement. • Pedicellariae - pincers to keep surface clean Class Asteroidean Sea stars: 1700 species (carnivores) • Sometimes have 50 arms that can be regenerated. • Predators of bivalves and snails, force open, invert stomach into or on, then digest outside of body. Class Ophiuroidea snake like: 2000 species • Central disc body, move by wringing their arms. • Arms break off easily and regenerate. • Detritivores and suspension feeders. • Basket stars have highly branched arms. Class Echinoidea (herbivores) Sea urchins/ Sand dollars: • Endoskeleton forms a “test” holes for tube feet, knobs for spine attachment. • Have moveable spines and tube feet for locomotion. • Aristotle’s Lantern is a system of muscles that controls the five teeth. • Graze on attached or drifting plant material. Class Holothuroidea Sea cucumbers: 900 Species (Detritivore) • Worm like echinoderms, mouth to anus is stretched. • Detritivore - deposit feeder with modified tube feet as tentacles to move food into mouth. • Evisceration - release guts/ internal organs out the anus as defense.