What are Mollusks?
Mollusks are an amazingly diverse group of animals that live in a wide variety of environments. They can be found inhabiting trees (Figure 1: D), gardens, freshwater ponds and streams, estuaries, tidal pools, beaches, the continental shelf, and the deep ocean. Some mollusks are excellent swimmers, others crawl or burrow in mud and sand. Others remain stationary by attaching themselves to rocks, other shells, or plants; or by boring into hard surfaces, such as wood or rocks. Adult mollusks can range in size from a few mm (0.1 in.) to over 22 m (>70 ft.) in length as documented for some giant deep-sea squids. Their weight can vary from a few mg (a fraction of an ounce) to over 227 kg (500 lb.) as recorded for the giant south Pacific Tridacna clams. The number of living species of mollusks has been estimated to range from 50,000 to 130,000. Everyone is probably familiar with some type of mollusk. They are the slugs and shelled pests in your backyard garden; the scallops, clams, mussels or
