Surf Clams, Duck Clams: Family Mactridae
I have a fairly large collection of surf clams, usually known as "Southern" Surf Clams (Anatina anatina). They are triangular in shape and range to 4" although many are small. Also part of this family are the duck clams, I have two complete smooth duck clams and one complete channeled duck clam. Both the smooth duck clam and the Channeled Duck clam have paper thin shells are are rarely found whole. The smooth duck clam is somewhat rare and is rarely found in Southwest Florida.
On left, Southern Surf Clam, on right a Smooth Duck Clam (S. Hutchinson Island)
The Smooth Duck Clam
The Smooth Duck Clam, Anatina anatina (Spengler, 1802), is a bivalve rarely found in Southwest Florida. It is a close relative of the more common Channeled Duck Clam, Raeta plicatella (Lamarck, 1818), with which it could be confused. Both have very thin, fragile shells, but the latter species, however, shows a sculpture of broader concentric ribs and more rounded outline. The Smooth Duck Clam, as other species of the family Mactridae, has its two long siphons (one sucks water in for filter-feeding, the other expels the used water) fused to form a single, elephant trunk-like structure. This is shown in the Amy Tripp’s illustration of the live clam (the photo was taken in Collier County). The photo also shows the clam’s digging foot on the right.