Heteropodids

Heteropodids, commonly known as pelagic snails or carinate snails, are a unique genus of marine gastropod mollusks belonging to the family Carinariidae. These fascinating creatures are entirely planktonic, meaning they drift with ocean currents. Unlike most snails, heteropodids have lost their shells almost entirely, retaining only a small, internal vestige. Their most striking adaptation is their modified foot, which has evolved into a large, fin-like structure used for swimming and propulsion. This allows them to navigate the water column, pursuing prey and avoiding predators.

Heteropodids are carnivorous and are typically found in tropical and subtropical oceans worldwide. They are often observed near the surface, especially at night. Their diet consists primarily of other planktonic organisms, including zooplankton and small fish. Some species are known to be bioluminescent, emitting light for communication or to attract prey. Reproduction in heteropodids involves external fertilization, with individuals releasing gametes into the water. The larval stage is also planktonic, eventually developing into the adult form. Their unusual morphology and pelagic lifestyle make them a subject of interest in marine biology and evolutionary studies.