Marine Living

The Class Gastropoda includes snails, slugs, limpets and sea hairs - all animals referred to as 'gastropods.' Gastropods are mollusks, and a extremely diverse group that includes over 40,000 species. Envision a sea shell, and you're thinking about a gastropod, although this class contains many shell-less animals as well.

Examples of gastropods: whelks, conchs, periwinkles, limpets, nudibranchs

Many gastropods, such as snails and limpets, have one shell. Sea slugs, like nudibranchs and sea hares, do not have a shell, although they may have an internal shell made of protein. Gastropods come in a wide variety of colors, shapes and sizes.

Such a diverse group of organisms has diverse feeding mechanisms. Some are herbivores, some carnivores. Most feed using a radula. The whelk, a type of gastropod, use their radula to drill a hole into the shell of other organisms for food.

Food is digested in the stomach. Because of the torsion process described earlier, the food enters the stomach through the posterior (back) end, and wastes leave through the anterior (front) end.

Some gastropods have both sexes; some are hermaphroditic. One interesting animal is the slipper shell, which may start out as a male and then change to a female.

Depending on the species, gastropods may reproduce by releasing gametes into the water, or by transferring the male's sperm into the female, who uses it to fertilize her eggs.

Once eggs hatch, the gastropod is usually a planktonic larvae called a veliger, which may feed on plankton or not feed at all. Eventually, the veliger undergoes metamorphosis and forms a juvenile gastropod.

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