Shell large, solid strongly inequivalve with lower valve bigger and deeper than the upper (rv). Rv depressed and almost flat. Outline irregular, generally suboval to subcircular. Pachydont hinge - a row of blunt teeth. Sculpture of short spines more pronounced towards the margin where they are concentrically lamellate. More prominent spines on the left side of the valve. Pallial line has no sinus. Internal margin encircled by a finely-crenulate-striate ridge.
exterior white, red, orange or purple; interior white usually splashed with pale or deep rose, particularly round the margins.
common size :
up to 70 mm in height.
Similar in size and sculpture to Chama lostoma Conrad, 1837, another Indo-Pacific species, which differs by a more inflated upper valve, by the presence of a distinct sinus-trough on the left side of the upper valve running from the umbo to the margin and by a smooth internal margin (crenulate ridge in C. pacifica).
BIOLOGY / ECOLOGY
Chamids are stenohaline nearshore inhabitants of rocky shores and coral reefs with a poor ability to withstand low salinity as that of estuarine regions (Bernard, 1976). The family is dioecious. The eggs are small, fertilization occurs externally, and the larvae probably undergo a prolonged planktonic development (LaBarbera and Chanley, 1971). Although the shells are usually heavily encrusted with epibiontic flora and fauna, none of the epibionts seems to have any detrimental effect on the growth and reproduction of Chama (Mienis et al., 1993b).
areas with little sedimentation; cemented to massive rocks in exposed areas, from the midlittoral zone to a few meters depth, attached to substrate by the left valve which is bigger; some individuals attach by the rv ("inverse form"). Off the coast of Israel, they share their habitat of bare, rocky outcrops of kurkar, a submerged aeolic sandstone, at depths of 12-15 m, with Spondylus spinosus. At depths 20-40 m, they form dense populations along with Spondylus spinosus, the surfaces of their shells providing strongholds for a diverse community of algae and invertebrates (Fishelson, 2000).