• 1) Widespread phylum of approx. 300 species; marine deposit feeders

• 2) The bizarre body plan includes:

  • a) two coeloms (small- tentacles, large- trunk)

  • b) completely invertable head end! (introvert)

  • c) crown of tentacles surrounding mouth

  • d) unusual gut (terminal mouth, mid-dorsal anus)

• 3) Related to molluscs by several distinctive characteristics:

  • a) molluscan cross (apparent at the 64 stage embryo)

  • b) eversible scraping buccal organ in larva; some think it may be related to the radula in gastropods

  • c) creeping muscular lip; some think it may be related to the creeping foot in benthic molluscs

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