How do Zebra/Quagga Mussels and Asian Clams Differ?
Zebra and Quagga mussels attach to hard surfaces via hair-like threads. Asian clams do not, rather, they burrow in soft sediments and/or gravel. Zebra and quagga mussels are the only freshwater mollusk species that attach via threads to hard surfaces. Zebra and Quagga mussels have thin, fragile shells. Asian clam shells are thicker, with distinct ridges. Zebra mussels seldom grow larger than 1 inch and typically have alternating light and dark strips (but some individuals do not have stripes). Quagga mussels may grow slightly larger than zebra mussels, but generally are about the same size. Asian clams can grow to 1.5 inches and are light yellow-brown to dark brown. Asian clams generally do not have stripes. However, damage to the proteinaceous outer layer of Asian clam shells sometimes exposes a lighter calcareous layer beneath that may appear to be stripes. Zebra mussel shells are D-shaped. Quagga mussel shels are more rounded, but both species of Dreissena have generally asymmetrica
