Anomia
Anomia is a genus of saltwater clams, marine bivalve mollusks in the family Anomiidae. The name Anomia was coined by Linnaeus in 1758, and the genus is a type genus for the family Anomiidae. They are commonly known as “jingle shells” because of the sound they make when shaken. Anomia have an unusual appearance and lifestyle compared to other bivalves.
Common Names
Anomia are commonly referred to as "jingle shells" due to the rattling sound produced by their shell when shaken. Other common names include "saddle oysters" and "false oysters," though they are not closely related to true oysters.
Characteristics
Anomia are characterized by a number of distinctive features:
- Asymmetrical Shell: One valve (the lower or "right" valve) is flat and often attached to a hard surface, while the other (the upper or "left" valve) is more rounded and can be attached to the flat valve by a tough, flexible stalk. The stalk is made of chitin and is often attached to rocks, seaweed, or other hard surfaces.
- Holes in Shell: The upper valve has a hole or "foramen" in the center that allows for the passage of the stalk.
- Byssal Threads: Unlike true oysters, Anomia do not produce byssal threads to attach themselves. Instead, they utilize their stalk for attachment.
- Limited Movement: While the stalk is flexible, it limits the ability of Anomia to move freely.
Environment
Anomia species are found in a variety of marine environments, including:
- Intertidal Zones: Anomia can be found in intertidal zones where they attach to rocks, shells, and other hard surfaces.
- Subtidal Zones: They are also found in subtidal zones, extending down to depths of several hundred meters.
- Various Substrates: Anomia have a wide tolerance for different substrates, attaching to rocks, shells, seaweed, and even other Anomia shells.