Pterotrachea

Pterotrachea is a genus of pelagic sea slugs belonging to the family Pterotracheidae. These are marine gastropod mollusks in the order Neotaenoglossa. Species within this genus are characterized by their entirely planktonic lifestyle, meaning they drift with ocean currents. They possess a gelatinous, transparent body that lacks a shell in their adult stage, though a small, fragile shell is present in the larval stage. This shell is often lost as the animal matures.

A distinctive feature of Pterotrachea is the presence of a large, muscular foot that has been modified into a propodium. This propodium is used for swimming and can be extended significantly. Their bodies are elongated and can appear somewhat streamlined. They are typically found in warm, tropical, and subtropical waters worldwide. Pterotrachea are carnivorous, feeding on other planktonic organisms, including small crustaceans and fish larvae. Their transparent bodies provide camouflage in the open ocean, making them difficult for both predators and prey to detect. Reproduction is usually sexual, with many species exhibiting hermaphroditism.