The Smooth Pink Scallop is found in the North Pacific Ocean from the Alaska Peninsula south to San Diego, California where it occurs on rocky or soft bottoms (common on gravel/mud) (
Cowles 2005).
Both the spiny pink scallop and the smooth pink scallop commonly bear sponge coatings on their valves. Both valves may be covered, but usually the heaviest growth is on the left one, the one normally in the upright position when the scallop is resting on the sea bottom. Is the sponge just a parasite, or does some benefit accrue to the scallop (making the relationship a commensalism), or perhaps to both participants (making the relationship a mutualism)? Early work on the subject suggests it is a mutualism, the scallop gaining protection from seastar predators that don't like to touch the sponge with their sensitive tube-feet, and the sponge benefiting from a clean place to live and from access to different habitats. Sounds good, but there are several questions arising from the study. Later research suggests, in fact, that it may be the sponge that benefits most by being kept clean through the scallops' valve clapping and swimming. Likely both studies are right, but there seems to be lots of opportunity here for further research. To read more about scallops and their sponges, go to A SNAIL'S ODYSSEY.
Both the Spiny Pink Scallop and the Smooth Pink Scallop are able swimmers and readily use this ability to escape from predators, such as sea stars and sometimes octopuses. Swimming is by jet propulsion, the force being generated by valve clapping and the jets of water emerging from apertures on either side of the hinge area. Large fleshy curtains (velum) prevent the water from wastefully exiting out the main valve aperture. Scallops swim therefore in a direction contrary to expectation, and resemble nothing more than a clacking set of false teeth if swimming directly towards you. For more on swimming in scallops, and to view some videos, go to A SNAIL'S ODYSSEY.
In southern British Columbia, this species reportedly lives about 6 years (Cowles 2005).
Note Author: Tom Carefoot, Department of Zoology, University of British Columbia
