Psolidium bidiscum Lambert, 1996
Common name(s): Pale creeping pedal sea cucumber
|Synonyms: Formerly thought to be Psolidium bullatum|
|Psolidium bidiscum from off Northwest Island at about 12 m depth. Scale = mm|
|(Photo by: Dave Cowles, July 2005)|
How to Distinguish from Similar Species: Psolus chitonoides, a much more obvious species, is much larger, has plates over 5 mm in diameter which have no nodules. Psolus squamatus also grows larger (6 cm) and is not pinkish or lavender.
Geographical Range: SE Alaska to central CA (Harbo, 1999).
Depth Range: Intertidal to 216 m; mostly subtidal. Recorded intertidally on one occasion in Hood Canal
Habitat: On rocks
Biology/Natural History: This species, newly described, was formerly thought to be Psolidium bullatum, which is nown known only from the Aleutian Islands and the Gulf of Alaska. Spawning is from late March to early May. The anterior end lifts up slightly, and the female releases up to 3000 golden yellow to light brown-orange eggs. Mature gonads can be seen through the sole: ovaries are tan and testes are white.
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I have found a number of specimens of this species around Rosario, especially on old shells such as are found in Octopus middens. We also find them on deep (around 100 m) trawls in the San Juan Channel.
This closeup of the anterior end shows the small oral tentacles around the mouth. Two tentacles are currently folding inside the mouth, probably for feeding.
This individual is living on the inside of a dead scallop shell.