Transcript Document
Echinoderms Thu Truong Phylum: Echinodermata "echino" - sea urchin, "spiny" "derm" - skin Example animals: Starfish Brittle Star Sea Urchin Sand dollar General Characteristics • Larvae - Bilateral Symmetry, cilliated, free-swimming • Adults - Pentaradial Symmetry • Endoskeleton - consists of calcium carbonate plates and spines, w/ thin cilliated epidermis • Pedicellariae - modified spines, pincer-like, keeps surface clean • Water Vascular System - network of fluid-filled canals that function in locomotion, feeding, and gas exchange. • Branches of the WVS become extended when filled with fluid (tube feet) • Ampulla - round muscular sac at the base of the foot, stores fluid and operates tube foot • Well developed coelom, but no excretory organs. • Digestive system most prominent, simple nervous system • Sexes are separate, both eggs and sperm are released into water Class: Crinoidea • Anatomy o Stalk - makes them sessile o "arms" resemble feather structure • Feeding/Behaviors o Remove suspended food from water o Oral surface is on upper side of disk o Tentacles coated with mucus to capture organisms Class: Asteroidea • Anatomy o Central disk, has 5 to more than 20 arms - tube feet underneath o Mouth lies on underside of the disc o Endoskeleton - series of calcareous plates, enables limted movement, moves slowly • Feeding/Behaviors o Carnivorous, eats by attaching itself to prey and secretes digestive enzymes • Gas Exchange/Secretion o Poorly developed circulatory system, rely mainly on coelom and coelomic fluid o Wastes are diffused outside through the tube feet and dermal gills • Reproduction o Sexual or Asexual Class: Ophiuroidea • Anatomy o Bodies similar to asteroidea, but the arms are more slender, enables it to move quicker o Tube feet not used in locomotion • Feeding/Behaviors o Tube feet used to collect and handle food Class: Echinoidea • Anatomy o Have NO arms, skeletal plates are flattened into a solid shell called a test o Sand dollars have flat bodies adapted for burrowing o Sea urchins have bodies covered with spines, move by tube feet • Feeding/Behaviors o Sand dollars feed on tiny organic particles in sand o Sea urchins feed on algae on the ocean floor with calcareous teeth Class: Holothuroidea • Anatomy o Elongated flexible body (muscular sac), mouth surrounded by circle of tentacles (modified tube feet) o Reduction of endoskeleton to microscopic plates o Highly developed Circulatory system, transports oxygen + nutrients • Feeding/Behaviors o Slow, live on bottom floor o Eviscration - digestive tract, respiratory structures, and gonads ejected from body (unfavorable conditions) • Response to Stimuli o if irritated will attack (shoots red tubules)