Invertebrates 5

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Invertebrates 5

• Phylum Echinodermata, and a wee bit of Chordata

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Branchpoints Protostomes vs. deuterostomes
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Phylum EchinodermataSpiny-skinned
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Echinodermata 4 key features

• Calcareous internal skeleton
• Parts Plates, spines and pedicellariae
• Why internal?
• Water vascular system (controls tube feet)
• Derived from coelom
• Layout
• Tube foot control
• Other functions
• Symmetry Pentamerous radial symmetry as
  adults/ bilateral as larvae
• Mutable connective tissue

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Body plan Other aspects

• Perivisceral coelom
• Houses organs
• Gas exchange
• Hydrostatic skeleton
• Digestive system
• Can be highly branched
• Complete in some
• Nervous system
• No brain
• Branches parallel water vascular system
• Sensory
• Eye spots
• Receptors associated with tube feet

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Class Asteroidea sea stars

• Body plan
• Feeding
• Respiration
• Protection

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Class EchinoideaSea urchins and others

• Body plan
• Feeding
• Respiration
• Protection

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Class OphioroideaBrittle stars, basket stars

• Body plan
• Feeding
• Respiration
• Protection

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Class CrinoideaSea lilies
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Class HolothuroideaSea cucumbers

• Body plan
• Feeding
• Respiration
• Protection

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Phylum Chordata

• Our closest invertebrate relatives are slimy sacs
  that pump seawater

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Parting shot Your closest invertebrate relatives