Mottled Sea Star     Evasterias troschelii



Clutching a piling at the Boston Harbor Marina, this eight to ten inch Mottled Sea Star is a hunter of barnacles, mussels, limpets, sea squirts along with other bivalves and snails.  Occurring along side the Purple Sea Star, it can be differentiated from it's cousin by it's small central disk, long, skinny arms, and mottled color pattern.  The body color ranges from orange to rust and even blue-grey.   Individuals can grow up to 16 inches.  It is fed upon by the Sunflower Sea Star, sea gulls and possibly larger crabs. 


The Mottled Sea Star can be found from Alaska to central California, normally in more protected waters than the wide ranging Purple Sea Star.  It inhabits both hard and soft substrates from the extreme low tide line to over several hundred feet water depth.


It breeds from mid April through the end of June. Eggs and sperm are released into the water column where fertilization occurs.  Like other sea stars, the young first become a bilaterally symmetrical larva (bipinnaria) swimming with other plankton.  Subsequent development continues the bilateral symmetry but adds arms, suckers and a new name (brachiolaria) to the larva.  The brachiolaria finally settles to the bottom where the posterior part metamorphoses, becoming a radially symmetrical, small version of the adult.