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Echinoderms

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

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Echinoderms

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  1. Echinoderms Thu Truong

  2. Phylum: Echinodermata "echino" - sea urchin, "spiny" "derm" - skin Example animals: Starfish Brittle Star Sea Urchin Sand dollar

  3. 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

  4. Class: Crinoidea • Anatomy • Stalk - makes them sessile • "arms" resemble feather structure • Feeding/Behaviors • Remove suspended food from water • Oral surface is on upper side of disk • Tentacles coated with mucus to capture organisms

  5. Class: Asteroidea • Anatomy •  Central disk, has 5 to more than 20 arms - tube feet underneath • Mouth lies on underside of the disc • Endoskeleton - series of calcareous plates, enables limted movement, moves slowly • Feeding/Behaviors • Carnivorous, eats by attaching itself to prey and secretes digestive enzymes • Gas Exchange/Secretion • Poorly developed circulatory system, rely mainly on coelom and coelomic fluid • Wastes are diffused outside through the tube feet and dermal gills • Reproduction • Sexual or Asexual

  6. Class: Ophiuroidea • Anatomy • Bodies similar to asteroidea, but the arms are more slender, enables it to move quicker • Tube feet not used in locomotion  • Feeding/Behaviors • Tube feet used to collect and handle food

  7. Class: Echinoidea • Anatomy •  Have NO arms, skeletal plates are flattened into a solid shell called a test • Sand dollars have flat bodies adapted for burrowing • Sea urchins have bodies covered with spines, move by tube feet • Feeding/Behaviors • Sand dollars feed on tiny organic particles in sand • Sea urchins feed on algae on the ocean floor with calcareous teeth

  8. Class: Holothuroidea • Anatomy • Elongated flexible body (muscular sac), mouth surrounded by circle of tentacles (modified tube feet) • Reduction of endoskeleton to microscopic plates • Highly developed Circulatory system, transports oxygen + nutrients • Feeding/Behaviors • Slow, live on bottom floor • Eviscration - digestive tract, respiratory structures, and gonads ejected from body (unfavorable conditions) • Response to Stimuli • if irritated will attack (shoots red tubules)

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