goose barnacles in Cornwall

Also known as: Tree geese

Every year we have one or more reports of goose barnacles, which derive their name from the fancied resemblance to geese. Indeed geese were thought (fortuitously!) by some to have arisen from these marine crustaceans and in mediaeval times religious men did "not scruple to feed off these birds at the time of fasting because they are not flesh nor born of flesh". The barnacles themselves are considered a delicacy in the warmer seas where they are common; hence when a boat drifted across the Atlantic and arrived in St Ives Bay smothered with them they were removed for sale! It is usual for them to be clustered and to be found on anything floating, be it wood, plastic or cork, on which they settle in the larval stage. Some related forms may be found on whales.

Goose barnacles
photograph by Susie Ray

Off British coasts there are four species that always settle on drifting objects in this way, all in the genus Lepas. They may still be alive on arrival, but soon perish in our comparatively low temperatures. The commonest is Lepas anatifera, the shelly plates (the capitulum) of which can reach 50mm whilst the muscular stalk (peduncle) varies from 40 to 900mm. It is the peduncle that is cooked and eaten. Mention must be made of a fifth species (Lepas fascicularis) which has very thin capitular plates. When juvenile, it will be found attached to twigs and even feathers, but as it grows it secretes its own spongy float; sometimes it is cast up in large numbers, especially on south-western shores.

Goose barnacles
photograph by Susie Ray

Goose barnacles have the same basic structure as the familiar stalkless acorn barnacles of rocky shores, and in the same way the calcareous plates protect feather appendages with which they net their food from the water.

Seaquest is always pleased to receive records of these crustaceans of the open seas and, if possible, a sample so that the species can be named.

Stella Turk

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