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Common piddock

Common piddock ©Nigel Phillips

Piddock

Piddocks are a boring bivalve. No, we don't mean dull... we mean that it bores into soft rock, creating a burrow. In fact, they're the opposite of dull - they glow in the dark!

Scientific name

Pholas dactylus and Barnea candida

When to see

January to December

Species information

Statistics

Length: up to 12cm Average Lifespan: 8 years
Common

Habitats

About

Piddocks are a strange group of clam-like shellfish that burrow into soft rocks such as clay and sandstone. They begin this process after settling as larvae and slowly enlarge and deepen the burrow as they grow. As such, they are essentially locked in and will live there for the rest of their lives. From the protection of their burrows they extend their siphon outwards to filter feed on organic matter from the water column. When the piddock dies, the empty burrows provide an additional habitat and refuge for other marine species, including other molluscs, juvenile crabs and even small sea anemones. Their long oval shells are distinctively wing shaped, giving piddocks their other common name of Angelwings.

How to identify

The common piddock's shell is thin and brittle, covered with concentric ridges and radiating lines and is dull white or grey in colour. There are several species of similar looking piddocks so if you are recording this as part of a recoding scheme be sure to take clear, close-up photos to help verifiers confirm your sighting.

Distribution

Patchy distribution around the coasts of England and Wales, as far north as Northumberland and the Solway Firth.

Did you know?

The common piddock glows in the dark! Through bioluminescence, it glows blue-green around the edges. Amazingly, the protein that creates this glow has been extracted from common piddocks and used to help identify when people are getting ill - it gives off light when it encounters chemicals produced by white-blood cells to fight infections. This can help doctors prescribe treatments faster and fight infections before they even really take hold!