Heteropoda

Heteropoda, pelagic Gasteropods, in which the 'foot' has become a swimming organ. In association with their active life on the surface of the ocean must be noted not only the locomotor foot, but the protective transparency, the highly-developed nervous system and sensory structures, eyes, ears, and smelling organ. The toothed ribbon in the mouth is also very elaborate. Technically the Heteropods are included among the Azygobranchs. Atlanta, with a large visceral dome and shell; Carinaria, with a reduced hump and small cap-like shell; and Pterotrachea, without a hump or shell, are the three types. See GASTERPODA, MOLLUSCS.