Predators & defenses
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  Camouflage
  In addition to the shell, defenses include camouflage, considered here, and SPONGE COATINGS, ANCHORING THREADS, and SWIMMING considered in other sections.
 
Research study 1
 

photograph of two scallops Chlamys sp. bearing sponge growthIt is likely that the sponge coatings on scallops Chlamys hastata and C. rubida provide an element of camouflage. Many of the photos of Chlamys spp. in the ODYSSEY are of animals poised to swim (because of the approach of a SCUBA-diver with camera). In this posture, the valves have opened wide, and the velar curtains are fully expanded and highly visible.  The curtains, rather than being drably coloured like the internal flesh, have quite striking coloration, and commonly bear patterns of contrastingly coloured vertical stripes.  Thus, although the sponge coating on the valves may act as crypsis camouflaging (no research has been done on this in west-coast species), what function might these other distinctive colours have?  Could they be distractive or disruptive to visual predators such as fishes or sea otters, or perhaps act as inter- or intraspecific alarm signals?

NOTE  octopuses prey commonly on scallops and have good vision, but some species tend to hunt mostly at night

 
Research study 2
 

photograph of a purple-hinged rock scallop Crassadoma gigantea bearing growths of hydroids, colonial tunicates and spongesAfter a few years of free-living existence, rock scallops Crassadoma gigantea cement themselves firmly to the rock surface.  After this their shells thicken and many different organisms begin to colonise the valve surfaces.  Although no research has been done on the function of these growths, it seems likely that camouflage might be one benefit.  Since sea stars are likely to be the main predator of adult rock scallops, the camouflaging may be of a chemical kind, rather than visual.

 

 

Purple-hinged rock scallop Crassadoma gigantea bearing
growths of hydroids, colonial tunicates and sponges 0.7X

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