Botryllus schlosseri (Pallas, 1766)

Star Ascidian

Botryllus schlosseri

Description: A colonial ascidian forming compact sheets. Zooids are elliptical and are arranged in star-systems around common cloacal openings, with typically 6-12 zooids in a system. This species comes in a vast range of colours and colour patterns. There is often a single dark spot at the centre of each zooid. 4mm thick x 70mm wide sheets.

Habitat: A very common ascidian, occurring on the lower shore, on seaweeds and kelp stipes in shallow water, and on exposed rock surfaces. Commonest in places with considerable wave or current exposure.

Distribution: Widespread and common all round the British Isles.

Similar Species: This species can be distinguished from Botrylloides leachi by the arrangement of its zooids into star-like systems around common exhalant openings rather than long, meandering systems. The other species which might be confused are the polyclinids Aplidium nordmanni and Sidnyum elegans.

Key Identification Features:

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

 Picton, B.E. & Morrow, C.C. (2016). Botryllus schlosseri (Pallas, 1766). [In] Encyclopedia of Marine Life of Britain and Ireland.
https://www.habitas.org.uk/marinelife/species.asp?item=ZD2090 Accessed on 2024-07-13

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