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Phylum Echinodermata

Phylum Echinodermata. Main Characteristics. Radial symmetry: PENTARADIAL Bilateral in free swimming embryonic stages 200 arms Comanthina schlegelii Rare species have 6 arms . Dipleurula larva. Skeleton . endoskeleton made of tiny calcareous plates and spines (OSSICLES)

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Phylum Echinodermata

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  1. Phylum Echinodermata

  2. Main Characteristics • Radial symmetry: PENTARADIAL • Bilateral in free swimming embryonic stages • 200 arms Comanthina schlegelii • Rare species have 6 arms Dipleurula larva

  3. Skeleton • endoskeleton made of tiny calcareous plates and spines (OSSICLES) • Acts like exoskeleton but its NOT! always contained within a layer of living tissue • Mutable Connective Tissue (MCT) :has special ability to be converted from stiff to soft in an instant

  4. Feeding • Some may use pedicellariae to aid in food capture • Two stomachs (cardiac and pyloric) • Evert cardiac stomach and secrete primary enzymes on the prey. • The digestive juices break down the tissue of the prey, which the asteroids then suck up and transfer to pyloric stomach. • http://www.youtube.com/watch?v=cQPlUlE769E

  5. Digestion • Cardiac Stomach • Pyloric Stomach • Connected to both the anus and pyloric ducts (caeca) • Pyloric Caeca • Makes bile • Finishes digestion • Absorbs nutrients

  6. Water Vascular System • Hydraulic network of fluid-filled canals • Water enters the MADREPORITE • Very powerful, but slow • Gas exchange • Feeding • Locomotion

  7. Respiration • Papullae (skin bumps) let in oxygen • Skin is very thin: oxygen can diffuse in from the surrounding water

  8. Decentralized Nervous System • No brain • Nerve ring surrounding the gut • Radial nerves run under the ambulacra • Sensory neurons are located primarily within the ectoderm of podia

  9. Reproduction • External Fertilization • Seperate sexes • Reproductive organs in each arm • Some species brood their young • 100,000,000 eggs at once!

  10. Asexual Reproduction • Fission of body parts • Regeneration: spines, arms, intestines

  11. A • CHARACTERISTIC • CHARACTERISTIC • CHARACTERISTIC • SPECIES • A. DESCRIPTION • B. WHERE FOUND • C. COLOR/SHAPE 3 4 2 B ASTEROIDEA 1 C CRINOIDEA ECHINODERMS ECHINOIDEA OPHIUROIDEA HOLOTHUROIDEA

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