sea squirt

Light bulb sea squirt

Latin name: Clavelina lepadiformis
Global Distribution: European coasts from south Norway to Mediterranean
UK Distribution: Common around most British and Irish coasts
Size: 2cm high
Diet: Filter feeding
Habitat: Attached to rock, stones and seaweed from lower shore to 50m deep.
Sources: Wood. 2009. Seasearch observer’s guide to marine life of Britain and Ireland. ISBN. 0 948150 46 7

Clavelina lepadiformis are sea squirts that are recognisable from their transparent bodies and white, or pale yellow, lines down their bodies and around their siphons (openings through which they inhale and exhale food), from which they get their light bulb appearance. They usually live in small, loosely clumped colonies where the ‘individuals’ are attached to each other at their base.

The eggs and larvae vary in colour depending on the region they’re from; in the Mediterranean, they are yellowish white or pink, and in other areas of Northwest Europe they can be red. The eggs and larvae seemingly develop within a particular body cavity (atrial cavity) of adult sea squirts, which is connected to the exhalant siphon from which water is exhaled.

Fun facts

  • Sea squirts are among the most closely related invertebrates to us.
  • In some areas Clavelina lepadiformis colonies ‘hibernate’ when conditions are less favourable.