The family Donacidae Fleming, 1828, is large family of about 100 recognised species found worldwide in warm waters (Huber, 2010). These clams generally live shallowly-buried just under the surface of wave-swept parts of beaches in the intertidal zone. Wave action often flushes the animals out, which they then move with the wash before quickly reburying themselves with their strong foot (K. S. Tan & Chou, 2000). In Singapore, donacids are abundant in some places where they occur and are sometimes collected for food. Being brightly and variably coloured, shells of donacids are quite attractive. Freshly dead articulate shells are usually widely splayed open, somewhat reminiscent of butterflies (Fig. 1). Empty shells sometimes occur in large numbers along the
strandline of some beaches, where beachgoers have often been seen to delight in making a small collection of them.