Ian Wallace

Ocean quahog

This large burrowing bivalve is found on sandy seabeds around much of the UK. It is the longest-lived animal known to man, with one individual found to be 507 years old!

Scientific name

Arctica islandica

When to see

January to December

Species information

Statistics

Length: Up to 13cm

Conservation status

On the OSPAR list of threatened and/or declining species and habitats in the North Sea. It is a Feature of Conservation Importance for which Marine Conservation Zones can be designated.

Habitats

Marine

About

The ocean quahog is a bivalve mollusc that lives buried in sandy seabeds all around the UK. It is a filter feeder, filtering organic matter from the water column using its siphon. Often, the siphon is all that is visible above the seabed and the end is sometimes nibbled off by hungry cod. They are very slow growing and extremely long-lived - with individual clams living for hundreds of years. It is the last surviving species of a family of similar clams that dates back to the Jurassic!

How to identify

A large black bivalve, with obvious concentric growth lines across the shell. When washed ahore, the papery shell covering is often sloughed off by sand and reveals a brownish-white shell beneath. They are identifiable predominantly by their large size (up to 13cm).

Distribution

In sandy seabeds around much of the UK and offshore.

Did you know?

The shell of the ocean quahog is full of information! Not only can it be used to learn the age of the animal - by counting lines in its shell, much like we count the rings in a tree - it can also be used to look at what the marine environment was like in the past. Because ocean quahogs are so long-lived, their shells can tell scientists how warm the seas were 300 years ago or even how salty the sea was 150 years ago. Amazing!

How people can help

Avoid eating seafood caught using bottom-towed gear, including scallops and scampi. Ocean quahogs are a protected feature of Marine Conservation Zones around England and out offshore.