What Habitats Are Mollusks Limited To?

Land

• Mollusks have evolved to inhabit land in the form of snails and slugs. These types of mollusks are further divided in the class Gastropod. Land snails and slugs are common amongst vegetation found in gardens, and well as in humid environments. Land snails are common throughout the Americas, Europe and Africa, and are eaten as a delicacy called escargot.

  Snails and slugs are vegetarians that feed on dark leafy greens. Their taste for most of the plants found in our gardens has led them to be classified as pests. Unlike many other invertebrates of their size, snails and slugs can live up to 30 years in captivity.

Freshwater

• Mollusks can be found in nearly every freshwater river and lake on Earth. In addition to freshwater snails, clams and mussels populate lake and riverbeds. Freshwater snails are vegetarians like their land-dwelling cousins that feed on primarily algae. The snail uses an abrasive set of teeth, called radulae, to scrape algae off rocks of the riverbed.

  Clams and mussels are classified as bivalves, which are filter feeders. These animals cement themselves in areas of high-flowing water. They use the current to intake the surrounding water and filter out algae and particulates they use as food.

Marine

• Gastropods and bivalves are very common throughout the tropical waters of the world. One unusual gastropod that can only be found in warm, shallow saltwater is the nudibranch, or sea slug. Sea slugs are relatives of land slugs, though they vary greatly in appearance. Unlike land slugs, sea slugs come in a variety of bright colors. Most nudibranchs are poisonous, and these bright colors advertise their toxins to predators.

  Nudibranchs, like snails and land slugs, are hermaphrodites-- meaning they contain both male and female reproductive organs. Though they contain both sets of reproductive organs, nudibranchs, slugs, and snails need to mate with another animal of their species to produce offspring.

Deep Sea

• Squids, cuttlefish and octopi inhabit some of the deepest waters of any known animal. Living in cold, deep waters has allowed these animals to grow to enormous sizes. The colossal squid, the largest known invertebrate, can grow to be over 1,000 pounds and 43 feet long.

  Inhabiting waters as deep as 6,000 feet has made finding the giant and colossal squid very difficult. It was not until February, 2007 that the first colossal squid was found alive. This squid weighed in at an estimated 990 pounds, and was captured off the coast of New Zealand.