E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Cucumaria pseudocurata Deichmann, 1938b
Tar Spot; Tar Spot Sea Cucumber
Family: Cucumariidae
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Distribution of Cucumaria pseudocurata in British Columbia
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Species Information

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Cucumaria pseudocurata is a small species, averaging 1.5 to 3 cm in length. The dorsal side varies from brownish black to light brown to yellowish grey, the ventral side from brown to white. The five bands of tube feet are in single or zigzag rows - the three ventral rows being more robust. There are no tube feet scattered between the rows. As a rule, there are eight equal-sized tentacles and two smaller ventral ones; but occasionally populations have been reported with a large proportion of equal-sized tentacles. This may have been due to misidentification, however. The tips of the tentacles are usually the most darkly pigmented. A genital papilla occurs between two of the dorsal tentacles.

Skin ossicles: oval perforated plates; typically with two central oval holes surrounded by smaller holes. In the southern part of C. pseudocurata's range, its ossicles are large and oval, but towards the north, its ossicles are more narrow and smoother around the edge.

Similar Species

In British Columbia Cucumaria pseudocurata might be confused with Pseudocnus curatus (formerly Cucumaria curata). P. curatus is usually black or dark brown, has 10 equal-sized tentacles, and tube feet scattered on the dorsal side. It is usually found at shallow subtidal or low intertidal - while C. pseudocurata is found at the mid intertidal level, near or among mussels.

To further confuse identifications, Cucumaria pseudocurata is hard to differentiate from Cucumaria vegae from Alaska. In fact, they appear identical to the naked eye. There is a gradual change in the ossicles of C. pseudocurata with latitude, but there is no clear distinction between it and C. vegae. Recent work with the DNA of these two species has confirmed that they are closely related, with only a 2% difference in the DNA between C. pseudocurata in the south and C. vegae in the north. In this type of analysis a difference of greater than 2% would indicate that the two forms were distinct species, 2% or less is not sufficient to separate them. Because these two names are already in the literature, and it is still not clear whether to synonymize them, I have retained them as separate species in this book. For the time being, I would identify a specimen from south of the Queen Charlotte Islands as C. pseudocurata and those from the Queen Charlottes north to the Aleutians as C. vegae.



pseudo = false, refers to similarity to Pseudocnus curatus
curata = to care for, refers to brooding of eggs

The mussel bed in which C. pseudocurata lives offers protection from the ocean swells. Its tentacles pick up various suspended particles to consume.

Unlike most sea cucumbers, Cucumaria pseudocurata spawns from mid December to mid January. Males raise the anterior end to release sperm bound in strings of mucus that sink to the bottom. The female spawns up to 340 bright orange eggs (mean diameter 1051 μm). She places the eggs between her ventral side and the substratum until they develop into crawling juveniles in two or three months. Cucumaria pseudocurata is reported to live for about five years, but is not reproductive until its third year.

The six-armed sea stars (Leptasterias spp.) are potential predators on C. pseudocurata. In California the Sunflower Star, (Pycnopodia helianthoides), feeds on the lower edge of sea cucumber aggregations.


Cucumaria pseudocurata is common in British Columbia. It is usually associated with the California mussel (Mytilus californianus) and, therefore, only found on the exposed coast. C. pseudocurata was seen near Bamfield on a semi-exposed rocky shore in great abundance among the alga Rhodomela, just below the mussel zone. Its distribution is patchy, being abundant in one part of the mussel bed and absent in another. In the southern part of the range, large aggregations inhabit the lower intertidal zone on the landward side of large rocks.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Range and Status Information Links

Additional Photo Sources

General References

Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 2024-07-12 4:17:27 AM]
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