Peanut Worms

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Phylum Sipuncula

• Peanut Worms

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Peanut Worms

• Defining Characteristics
• Anterior part of the body forms an eversible and
  fully retractable proboscis with a mouth at the
  end

• Multicellular bodies (urns) in the coelomic fluid

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Sipunculan Body Plan
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Peanut Worm Feeding

• Mucus covered tentacles trap organic material
  from the surrounding water or sediment
• During burrow formation sediment may be ingested
  directly
• Mouth and anus are both located anteriorly
  resulting in a U shaped gut

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Sipunculan Anatomy
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Circulatory System

• Unlike the annelids sipunculans lack a
  circulatory system with a heart and blood vessels
• Excretion occurs via urns
• Cells that float in the coelom collecting waste
  products bringing them to nephridia

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Reproduction

• Sexes are separate and fertilization occurs in
  the sea
• Trochophore larvae forms resembling Annelida and
  Mollusca larvae
• Some species have a trochophore that further
  develops into a pelagosphera

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Local Species

• Hermit Sipunculan (Phascolion strombus)
• Lives in the shells of gastropods
• Rock-Boring Sipunculan (Themiste alutacea)
• Associated with calcareous surfaces (coral and
  limestone)
• Burrowing Sipunculan (Sipunculus nudus)
• Burrows in fine and coarse sands