Broad disc with five or more long arms. The aboral skeleton is meshlike; the plates bear pseudopaxillae. The marginal pseudopaxillae are larger than the aborals. Oral intermediates are present. The adambulacral spines consist of two series at right angles to each other. The mouth plates are prominent. No pedicellariae.
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Solaster stimpsoni is the most common of the four species of Solaster. It has ten arms (occasionally nine) up to 23 cm long. The body is typically orange or yellow with a blue or purple band on the aboral side of each arm that join at the central disc. Less commonly, the whole body is blue. The ratio of arm to disc is from 2.3 to 4.4. The aboral pseudopaxillae are intermediate in size and number between S. endeca and S. dawsoni, with 6 to 12 peripheral spinelets per pseudopaxilla. The marginals are confined to the oral side of the arms; the wide inferomarginals, at right angles to the arm axis, form an obvious regular row adjacent to the adambulacrals. The superomarginals, just above and between each inferomarginal, are about the same size as the aboral pseudopaxillae. The oral interradial area has pseudopaxillae similar to those on aboral side. A row of oral intermediates runs about one-fifth of the way along the arm. The adambulacrals have 2 or 3 short furrow spines, half as long as the transverse series of 6 to 8 blunt spines on the oral surface. Each pair of mouth plates is broad and shovel-shaped with 6 to 8 heavy marginal spines, larger than any others on the sea star, and one row of 4 to 8 suborals.
Solaster endeca may have a striped arm as well, but the arm-to-disc ratio is much smaller than S. stimpsoni.
In Puget Sound, Solaster stimpsoni feeds primarily on Pseudocnus lubricus (the Aggregating Sea Cucumber), and less commonly on these other sea cucumbers: Cucumaria miniata, Eupentacta quinquesemita, E. pseudoquinquesemita and Psolus chitonoides. It seems to prefer the Eupentacta species, even though it can find P. lubricus in large aggregations. Parastichopus californicus (the California Sea Cucumber) swims away when contacted by S. stimpsoni. A small number feed on sea squirts, lamp shells and sea pens. S. stimpsoni is not known to feed on other sea stars.
This sea star breeds from late February to early March. Its large, buoyant eggs (0.94-1.05 mm in diameter) have total and equal cleavage and develop into a planktonic lecithotrophic larva with three brachiolarian arms. The larva settles 8-10 days after fertilization. It forms five arms initially, then adds more in sequence between the first and fifth arms. Metamorphosis is complete 40-50 days after fertilization. Juveniles are often found among the tubes of the polychaete worm Phyllochaetopterus. S. stimpsoni has two commensal scale worms: Arctonoe pulchra and A. vittata. Twenty-one per cent of specimens sampled were infected with a parasitic green alga, Diogenes.
The south Bering Sea to Oregon and to Japan, from the intertidal zone to 60 metres deep. Usually on rocky substrates; less commonly on sandy mud. Common in this region (the area from Glacier Bay to Puget Sound to a depth to 200 metres).
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:
2023-01-26 1:14:18 PM]
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