Penion
Penion is a genus of marine gastropods, commonly known as “pen shells,” belonging to the family Pinnidae. These bivalves are characterized by their elongated, wedge-shaped shells with a prominent, pointed umbo. They are known for their byssal threads, strong, silky strands that anchor them to rocky surfaces or other substrates. Penion species are distributed worldwide in tropical and subtropical waters.
Common Names
The common names for Penion species are often derived from their distinctive shell shape. Some common names include "pen shells," "feather shells," and "pinna shells."
Characteristics
Penion species exhibit the following key characteristics:
- Elongated, wedge-shaped shells: Their shells are typically thin and fragile, with a prominent, pointed umbo at the anterior end.
- Byssal threads: Penion species secrete strong, silky byssal threads, which they use to anchor themselves to solid surfaces like rocks, coral, and other shells.
- Filter feeders: They are filter feeders, extracting food particles from the surrounding water.
- Symbiotic relationships: Some species of Penion form symbiotic relationships with other marine organisms, such as hermit crabs.
Environments
Penion species are typically found in shallow, coastal waters, particularly in areas with rocky or coral substrates. They prefer warm, tropical and subtropical waters, and are often found in sheltered bays, lagoons, and estuaries.