Pinna
The genus Pinna encompasses a group of large, bivalve mollusks commonly known as fan mussels or pen shells. These marine invertebrates are renowned for their distinctively shaped shells, which resemble a fan or a pen. They are found in various regions of the Mediterranean Sea, the Atlantic Ocean, and the Indo-Pacific. Pinna species are often characterized by their substantial size, with some individuals reaching lengths of over 1 meter. Their shells are composed of two valves that are hinged together along a dorsal line. The outer surface of the shell is typically adorned with radial ribs and a series of concentric growth lines, while the inner surface is smooth and pearly.
Common Names
Fan mussels are known by various common names depending on the geographic location and local language. Some of the most common names include:
- Pen shell
- Fan mussel
- Sea pen
- Noble pen shell
- Mediterranean fan mussel
Characteristics
Pinna species exhibit several distinct characteristics, which include:
- Shell shape: The shell is elongated and fan-shaped, with a prominent hinge line and a wide, rounded base.
- Shell size: Fan mussels can grow to considerable sizes, with some species reaching lengths exceeding 1 meter.
- Shell ornamentation: The outer surface of the shell is typically ornamented with radial ribs and concentric growth lines.
- Byssal threads: Fan mussels anchor themselves to the seabed using strong byssal threads secreted from the foot.
- Feeding mechanism: They are filter feeders, using their gills to extract food particles from the surrounding water.
Environments
Fan mussels are found in a variety of marine environments, including:
- Sandy bottoms: They typically inhabit sandy or muddy bottoms, where they can anchor themselves using their byssal threads.
- Seagrass meadows: Fan mussels are often found in seagrass meadows, where they can benefit from the protection and food sources provided by the seagrass.
- Rocky reefs: Some species may also occur on rocky reefs, where they can attach to crevices or overhangs.
References
For further information on Pinna species, you can consult these reliable resources: