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

Lethasterias nanimensis (Verrill, 1914)
Sea Star
Family: Asteriidae

© Aaron Baldwin  Email the photographer   (Photo ID #6808)

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Distribution of Lethasterias nanimensis in British Columbia
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Introduction


Family Description:

Five or more arms. At least one adambulacral is fused into an adoral carina. The adambulacrals are wider than their length. Crossed and straight pedicellariae are present, the former usually in dense tufts around the spines. The aboral skeleton is meshlike. The tube feet are arranged in four rows.

Species Information

Lethasterias nanimensis has five long flexible arms with numerous, black-tipped spines wreathed with crossed pedicellariae. The background colour on the upper surface is yellowish-brown. In alcohol, the black colour in the spines may be lost. The arms up to 30 cm long and the arm-to-disc ratio is 8. The aboral spines form a regular carinal series, but other spines are less regular. The tips of the spines tend to be fluted like a drill bit. The crossed pedicellariae have teeth of equal size. Occasional straight pedicellariae occur on the oral surface near the mouth plates. The marginals consist of a row of superomarginals with one spine (usually blackish) and a row of inferomarginals with two spines, the latter usually gouge shaped and bearing a cluster of pedicellariae on the distal side. Small clusters of up to ten papulae occur between the spines, especially near the marginals. The smaller adambulacrals (33 plates per 10 inferomarginals) each bear two spines, the proximal one smaller. The mouth plates are proximal to a short adoral carina of two fused adambulacrals and they each bear two marginal spines, one longer than the other, and one or two suborals.

The subspecies L. n. chelifera has more numerous straight pedicellariae on all parts of the body, with two or three longer curved interlocking fingers. The aboral spines are less regular and smaller.

Similar Species

Lethasterias nanimensis might be confused with Orthasterias koehleri or Stylasterias forreri, but the living colours are quite distinct. O. koehleri has a row of oral intermediates and two rows of inferomarginals. The c

Biology


The digestive glands are long and voluminous, reaching nearly to the tips of the arms. The gonopores occur at the arm angle near the superomarginal plates. The spacious ventral stomach has very strong retractors. When handled this species readily drops its arms. Bob Stone at the Auke Bay Marine Lab reported seeing hundreds of individuals on a shallow cobble bottom where the sea cucumber Cucumaria frondosa japonica was common. A month later none could be found at that spot.

Distribution

Distribution

Southeast Alaska. Found in the shallow subtidal zone to 102 metres on mud, sand, gravel or boulders. I observed one specimen of Lethasterias nanimensis on a sand slope near Juneau. The species account for L. nanimensis was based on two specimens. The type specimen ostensibly from Departure Bay in Nanaimo, B.C., and another collected by the steamer Albatross in Juan de Fuca Strait. Fisher (1928) has doubts about the type locality data, and in 25 years of diving I have never seen this species in B.C. I identified museum specimens from around Juneau as L. nanimensis. Others have been reported farther south in Stephen's Passage, but its existence in northern B.C. has yet to be confirmed.

The subspecies L.n. chelifera ranges from the Bering Strait to the Sea of Japan and to Kodiak Island, Gulf of Alaska, from low tide to 224 metres deep. Fisher (1928) points out that the subspecies is the more important boreal form, ranging from the Bering Sea to the Gulf of Alaska, so we have the odd situation of the subspecies being widespread and the typical species having a limited distribution in Southeast Alaska.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
COSEWIC
UnlistedUnlistedUnlistedUnlisted
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) 2019. 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: 19/11/2019 2:54:04 AM]
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