Marine Wildlife Encyclopedia
Common Sea Squirt Ciona intestinalis
The common sea squirt has no supporting structures in its adult form, so when it is seen out of water, it resembles a blob of jelly that may squirt out a jet of water when prodded. It is a typical solitary tunicate, whose internal structures are visible through its pale, greenish yellow, gelatinous outer covering, called a test or tunic, which is smooth and translucent. It has two yellow-edged siphons and uses the larger of these, the inhalent siphon, to draw in water; the smaller, exhalent siphon is used to expel water, and its opening has six lobes, while that of the exhalent siphon has eight. The common sea squirt lives up to its name and is found attached to a wide variety of rocks, reefs, seaweeds, and, in particular, man-made structures. The legs of oil platforms and jetties, for example, are often festooned with this sea squirt.
The Common Sea Squirt as Cleaning Crew
In sheltered sea lochs and harbors, the common sea squirt often covers large areas of rock or wall. In spite of its small size, it is able to filter several quarts of water per hour, filtering out plankton and other organic particles and leaving the water much clearer than it might otherwise be.