Pteropods: Swimming snails of the sea

The pteropods are a fascinating group of snails that spend their entire lives swimming or drifting in the ocean and never touching the bottom. Pteropoda means wing-foot referring to their muscular foot that has evolved into a pair of wings allowing them to take advantage of the Earth’s largest habitat, the open ocean. There are two distinct types of pteropods – those with shells and those without. The shelled pteropods produce a net of sticky mucous to passively collect and eat marine snow. The pteropods without shells are all carnivores and as far as we know, feed solely upon the shelled pteropods. The pteropods are a widespread and diverse group, and play an important role in the oceanic food web. However, the increasing acidity of the ocean leaves the fragile pteropod shells vulnerable to dissolving, challenging the health and growth of these species. These impacts may reach beyond pteropods to the variety of animals, including fishes, sharks, squids, and marine mammals that eat them.