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About Polychaetes
Worms that are not polychaetes



Priapula [illustrator: Damon Kowarsky]

Priapulans are unsegmented marine worms with bilaterally symmetrical bodies, often appearing radially symmetrical. The anterior region is the introvert with the mouth at the anterior end of the eversible pharynx. The introvert has 20 or 25 longitudinal rows of chitinous papilla-like scalids. The posterior region is the abdomen, with the anus located at the posterior end. Circular bands of muscle in the abdomen result in 30-100 annulations of that body region.


Priapulans (also known as Priapulida) are predatory worms found in soft sediments. Only 17 species of Priapula are known world wide, ranging from a few mm to over 100 mm in length; one species is interstitial. Priapulans occur in all oceans but are sparsely distributed. Individual species tend to be widely distributed, for example over either northern or southern hemispheres.

The primary source for identification of priapulans is van der Land (1970), which treats all 17 known species. The unidentified specimen illustrated here, from Bass Strait, is apparently the first published record of a priapulan from Australian waters.


Land, J van der. 1970. Systematics, zoogeography, and ecology of the
Priapulida. Zoologische Verhandelingen uitgegeven door het Rijksmuseum van Natuurlijke Historie te Leiden 112, 1-118.

Schreiber, A, Eisinger, M and Storch, V. 1996. Allozymes characterize sibling species of bipolar Priapulida (Priapulus, Priapulopsis). Polar Biology 16, 521-526.