Phylum Echinodermata

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Phylum Echinodermata

• Biology I Honors

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Examples

• Sea Stars (star fish)
• Sea Urchins
• Sand Dollars
• Sea Cucumbers

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Habitat

• Marine

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Symmetry

• Radial as adults (top image)
• Bilateral as larva (bottom image)
• Larval development links the echinoderm phylum
  most closely with phylum chordata (OUR phylum)

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Tissue layers

• 3
• (image is se star surrounded by sea cucumbers)

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Support/Skeletal

• Endoskeleton with spines protruding through skin

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Muscular

• Water vascular system instead of muscles
• Water pumps through tubes and operates little
  suction cup type structures called tube feet
• Tube feet provide movement

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Digestion

• Complete
• Mouth on bottom
• Anus on top
• Stomach ejects through mouth
• Prey is digested
• Stomach and prey return into the body through
  mouth

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Respiration

• Gills
• On the skin

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Excretion

• Amoeboid Cells carry wastes out of the body

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Circulation

• Open
• cilia circulate the fluids through each arm

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Nervous

• nerve ring around the central disc instead of a
  brain. Eyespots on the tips of arms sense light.

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Temperature Regulation

• Ectothermic

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Reproduction

• Echinoderms have the ability to regenerate new
  parts asexually.
• They also have separate sexes with sex organs in
  each arm.
• Sexual reproduction involves releasing gametes
  into the water (external fertilization).