Shell large extremely thick and heavy, rather well inflated. Inequilateral with elevated beaks in the anterior part. Outline triangular, subovate. Sculpture of numerous concentric lines widely spaced at the umbones, closely spaced near the margins.
shell white or grey, sometimes with brown zigzag markings. Internallly white often stained violet.
common size :
shell 60-120 mm, up to 150 mm in length when fully grown.
Mercenaria campechiensis (Gmelin) is a very closely related species that grows to a larger size and is found from Virginia to Texas.
BIOLOGY / ECOLOGY
Suspension feeder. Temperatures below 80°C have been shown to dramatically reduce clam growth. Predatory mortality during juvenile stages is a primary factor controlling recruitment of natural populations. Experiments have shown that high mortality can be compensated by warm water temperature (using warm estuarine waters) and using gravel as substratum to protect seed clams from crab predation (Summerson et al., 1995). The older-aged clams are estimated to be 38 years and sized 118 mm (Walker, 1994); suceptible to toxic algal species under bloom conditions (Bricelj, 1993).
muddy bottoms, from the intertidal zone to a depth of 10 m.