Solenidae, Pharidae and Solecurtidae - Razor Clams
These three families are typically known as razor clams. Solecurtidae, the short razor clams, have shells that are stout, rectangular, long and narrow. The outer shell is smooth, sometimes with fine concentric growth lines. The shells may be covered by a thin brown outer skin (periostracum). Both anterior and posterior ends are widely gaping. These shells somewhat resemble the tellins but don't have the posterior twist in their beaks like the tellins do. They bury themselves in soft mud, and their burrows can be fairly deep, up to 50 cm (20 in) beneath the surface. Their siphons can extend many times the shell length to reach the sediment surface. There are 3 species of Solecurtidae found in Texas waters.
The jackknife clams (Solenidae and Pharidae) have small, smooth shells that are long, narrow and very fragile. The hinges occur near the anterior end of the shell. The edges of their shells can be razor sharp. They have a strong muscular foot that allows then to burrow quickly into sandy bottoms and are generally found in the intertidal and high subtidal zones. Some have hemoglobin-like oxygen storing molecules, similar to some arks, that contain a red pigment that resembles blood. All of these clams are edible. There is one species in each family found in Texas waters.