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Phylum Sipuncula. Peanut Worms. Eversible proboscis. 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. Sipunculan Body Plan. Peanut Worm Feeding.
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Phylum Sipuncula Peanut Worms Phylum Sipuncula
Eversible proboscis 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 Phylum Sipuncula
Sipunculan Body Plan Phylum Sipuncula
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 Phylum Sipuncula
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 Phylum Sipuncula
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 Phylum Sipuncula
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 Phylum Sipuncula