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Eupentacta pseudoquinquesemita has the same body form as E. quinquesemita, with five rows of non-retractile tube feet and smooth spaces between. It grows up to 10 cm long. The skin is soft and pliable. The general colour is a creamy white with the tentacles being a faint peachy colour. Typically, bits and pieces of shell and other debris adhere to the tube feet. There are eight equal-sized tentacles and two tiny ones on the ventral side. The tentacles are usually retracted when the species is collected.
Skin ossicles: numerous, porous ovoid bodies as well as more delicate cups. Cups are small oval plates shaped like a shallow dish with a rim of knobs. This species has few, if any, baskets.
The external differences between the two Eupentacta species are subtle and not always consistent. Externally, the tube feet of E. pseudoquinqesemita are finer and more numerous, with a broad space between the series of tube feet. It also has a softer body. Without having the two species side by side, this description may not help too much. To be sure, check the skin ossicles for the presence of baskets or cups, as described above. The habitat will provide a clue as to which species you have (see below). In British Columbia the most common intertidal species is E. quinquesemita, but in southeast Alaska E. pseudoquinquesemita is more common.
pseudo = false quinquesemita = five foot paths
Little is known about the biology of this species, because it is so easy to confuse the two Eupentacta. Reports in the literature could refer to either species. Gut contents revealed a mixture of filamentous algae and diatoms as well as detritus and inorganic particles. In the field they were not seen to feed during the winter. Thirty-eight per cent of Eupentacta pseudoquinquesemita specimens examined in Puget Sound contained parasites, primarily the gastropod Thyonicola americana. The wormlike, coiled parasite attaches to the posterior third of the intestine.
In the southern part of its range, E. pseudoquinquesemita tends to be subtidal. It is often found on soft substrata. It commonly has particles of shell or seaweed attached to it. One study described it as not occurring on float communities, but restricted to exposed hard surfaces subject to currents (density as high as 100/m²).
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:
2023-10-01 10:50:11 PM]
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