About Carditamera affinis (G.B.Sowerby I, 1833)
Carditamera affinis has a roughly trapezoidal shell with 15 raised ribs. In some individuals, small spines or scales appear on the posterior ends, which are the parts furthest from the hinge, of the larger ribs. Both the exterior and interior of the shell are colored in shades of brown. Recorded shell lengths range from 50.7mm to 101.2mm, or 2 to 4 inches. This species is distributed in the eastern Pacific Ocean from California to Peru, and also occurs in the Gulf of California and the Galapagos Islands. It was among the specimens collected from the Gulf of California by John Steinbeck and Ed Ricketts, an expedition recounted in The Log From The Sea Of Cortez. In 2012, a very similar-looking species, Carditamera bajaensis, was split from C. affinis. Both species are found in the Gulf of California but occupy different habitats. C. affinis is epifaunal, meaning it lives at the surface of the seabed on rocks and in crevices. By contrast, C. bajaensis is infaunal or semi-infaunal, living completely or partly buried in sand, mud, or loose rocks. C. affinis is a shallow-water species, found from the intertidal zone down to 27 meters, or 90 feet, deep.
