Ascidiella aspersa (O F Müller, 1776)

Ascidiella aspersa

Description: A tall solitary sea squirt usually found in clumps and attached by its base. The body is oval with a fluted oral siphon at the top and an upward-directed atrial siphon 1/3 of the way down the side of the body. The test is grey and semi-transparent, usually covered with lightly adhering detritus, filamentous algae, etc. There is a series of lighter marks around the edge of each siphon, and the large oral tentacles can easily be seen inside the oral siphon in expanded animals. Typical size 50-100mm.

Habitat: Usually in shallow sheltered sites, harbours, sea laughs, etc., attached to shells or pebbles on mud or on silty rock if this is present. Often abundant.

Distribution: All around the British Isles and from Norway to the Mediterranean. Scarce in the North Sea.

Similar Species: Ciona intestinalis always has yellow marks around the siphons, and is different in shape and consistency. Ascidia spp. have firmer tests. Ascidiella scabra is usually smaller and more squat, with both siphons more or less on a level.

Key Identification Features:

• Thin grey test, colourless zooid.
• Basal attachment.
• Fluted oral siphon, atrial siphon 1/3 way down side of body.

Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.

WoRMS: Species record : World Register of Marine Species.

iNaturalist: Species account : iNaturalist World Species Observations database