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

Solaster dawsoni is carnivorous. In 36 of 55 feeding observations in Puget Sound, it preyed on S. stimpsoni and consumed the sea star in an average of 4.5 days. This predator ate about 17 S. stimpsoni per year. In the Strait of Georgia, Dermasterias imbricata seems to be the prey of choice based on diver observations. S. dawsoni also attacks its own species, but its success rate is low because of a well-developed escape response. S. dawsoni bends its arms back and pushes the attacker off while rapidly moving away (10 cm/min.). This sea star also preys upon Crossaster papposus, Leptasterias hexactis, Mediaster aequalis, Evasterias troschelii, Henricia leviuscula, Asterina miniata, small Pisaster ochraceus and Pycnopodia helianthoides. When attacking, S. dawsoni can reach a speed of 12 cm per minute. In a Bodega Bay study, D. imbricata, Pisaster brevispinus and large P. ochraceus appeared to avoid predation; the latter two used their pedicellaria to ward off S. dawsoni. The strongest escape responses are shown by A. miniata, H. leviuscula, L. hexactis and Pycnopodia helianthoides; and the California Sea Cucumber (Parastichopus califomicus) swims away when contacted.

S. dawsoni breeds from late February to early March. Large buoyant eggs (0.94-1.05 mm) undergo total and equal cleavage to a planktonic lecithotrophic larva with three brachiolarian arms. Settlement occurs 8-10 days after fertilization and metamorphosis 40-50 days after. The juvenile has five arms initially and adds the remaining arms in sequence between the first and fifth. I observed three specimens spawning on April 13 1977 near Victoria. Juveniles have been reported to be quite common among tubes of the polychaete Phyllochaetopterus. S. dawsoni has two commensal scale worms: Arctonoe fragilis and A. vittata.