Phascolopsis gouldii (De Pourtalès, 1851)
This species is only found on the Atlantic coast of North America. This slender, smooth, light brown worm has been used as a source for teaching and research among the biological community. The deciduous hooks are present in juveniles but are absent in adults.
(From Stephen an Edmonds, 1972, Cutler, 1994)
External anatomy
Introvert about one-third of the trunk length, with deciduous hooks (26-40 µm tall), widely dispersed and arranged in ill-defined rings. Present in juveniles (in worms after 3-4 mm long) but absent in adults. Small papillae arranged in rings are present on the distal part of the introvert.
Trunk up to 150 mm long (commonly 50 -100 mm).
Skin bodies cover the body wall, but no distinct papillae.
Tentacle crown consists of many peripheral tentacles around the mouth.
Internal anatomy
26-30 longitudinal muscle bands (LMBs) frequently anastomose.
Circular muscle layers continuous.
Two pairs of retractor muscles, attached in the anterior half of the trunk. Dorsal pair originating anteriorly to the ventral pair.
Contractile vessel without villi.
Spindle muscle arises in front of the anus and is not attached posteriorly.
A pair of unattached free nephridia, opening slightly anterior to the anus.
Most common size is between 50-100 mm in trunk length, but it can be up to 150 mm (Cutler, 1994).
(From Cutler, 1994)
Atlantic coast of North America from Florida to Nova Scotia. It is rare south of Long Island.
From low tide line to shallow subtidal depths (Cutler, 1994).
The breeding season in Newport, Road Island begins in the middle of June and extends to middle of September (Gerould, 1907).
For many years this species has been used as a teaching and research resource (e.g. Abercrombie and Bagby, 1984; Boore and Staton, 2002; Oglesby, 1982; Vanin et al, 2006).