Puzzling Dwarf Conchs
Some groups of mollusks, such as cowries and true conchs (Strombidae) may display dwarfism. Shells in the dwarf forms show the features of mature individuals, such as thickened, flared, or ornamented outer shell lip, but at a much smaller size than expected for that species. For different reasons, most probably unknown, those mollusks reach reproductive maturity at smaller size than “normal” individuals of the same species. Environmental factors, such as overcrowding in boring bivalves, could trigger dwarfism. This composite image of Hawkwing Conch, Lobatus raninus (Gmelin, 1791), shells shows a juvenile (left; 47 mm, from Craig Key, FL), a normal-sized adult (center; 86 mm, from Wood Cay, Bahamas), and a dwarf (right; 46 mm Lake Worth, FL); for comparisons, all photos are at same scale. Notice that the dwarf shows a thickened lip, which is lacking in the juvenile shell of about same size. All shells illustrated are from the Museum collection. Please support the great collection work done at the Museum by donating today!