Common piddock

Common piddock ©Nigel Phillips


Scientific name: Pholas dactylus
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!

Species information


Length: up to 12cm Average Lifespan: 8 years

Conservation status


When to see

January to December


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 are a des res 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.


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!

How people can help

Molluscs provide a vital link in the food chain for many of our rarer species. Across the UK, The Wildlife Trusts are working with fishermen, researchers, politicians and local people towards a vision of 'Living Seas', where marine wildlife thrives. Do your bit for our Living Seas by supporting your local Wildlife Trust or by checking out our Action pages.