The Comb Bittersweet, Tucetona pectinata (Gmelin, 1791) is the most common out of three locally found species of the bittersweet family, the Glycymerididae. Its shell may reach 30 mm (about 1.2 inches), and is circular, with a sculpture of 20–35 relatively wide ribs that are flat in cross-section. The shell hinge has about 20–24 small “teeth”. The color is variable, usually white to grayish-white with irregular brown streaks of variable hues. Bittersweet clams have numerous, simple eyes that resemble those in insects. The eyes can be seen as tiny dark dots along the mantle edges of the clam in the photo on right, taken by Amy Tripp on Kice Island, Collier County, Florida.
The Comb Bittersweet, Tucetona pectinata. On left, shell from Sanibel, photos by José H. Leal; on right, live clam from Kice Island (Collier County) showing eyes, photo by Amy Tripp.