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Echinoderms

“Spiny Skin”

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Characteristics

  • Spiny skin.
  • Radial Symmetry.
  • Internal skeleton.
  • Water vascular system.
  • Tube feet

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Endoskeleton

  • Composed of calcium carbonate plates.
  • Often bumpy or spiny.

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Water Vascular System

  • An internal network of fluid filled canals connected to the tube feet.
  • Responsible for many of the life functions.

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Water Vascular System

  • Water is pumped into and out of tube feet.
  • Causes tube feet to expand and shrink, creating a vacuum on whatever the foot is touching.
  • Hundreds of tube feet acting together can create enormous force.

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Tube Feet

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Feeding

  • Carnivores use tube feet to pry open bivalves.
  • Stomach then comes out of the animals mouth to digest the food.

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Feeding

  • Herbivores scrape algae.
  • Filter feeders capture plankton.
  • Detritivores scrape the ocean floor.

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Respiration

  • Gas exchange occurs on the tube feet.

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Internal Transport

  • Digestive glands and body cavities.

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Excretion

  • Undigestible wastes out anus.
  • Metabolic wastes diffuse out of tube feet.

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Response

  • Primitive nervous system.
  • Nerve ring around mouth with radial nerves to body sections.
  • Light sensitive cells in arms.

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Movement

  • Tube feet.

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Reproduction

  • Most are male OR female, though some species are hermaphroditic.
  • Sperm and eggs released into water.
  • Motile larvae have bilateral symmetry.

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Regeneration

  • Starfish can regenerate lost arms.
  • Pieces can grow into new starfish.

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Echinoderm Classes

  • Starfish

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Echinoderm Classes

  • Brittle stars.

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Echinoderm Classes

  • Sea urchins and sand dollars.

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Echinoderm Classes

  • Sea cucumbers.

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Echinoderm Classes

  • Sea lilies and feather stars.

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