A sea squirt (Pyura microcosmus)

Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help



A solitary sea squirt up to 3 cm in length with an ovoid body and terminal oral siphon. The thick, leathery test is wrinkled, reddish with longitudinal white stripes, most noticeable on internal surfaces. Pyura microcosmus is often fouled with various epibionts, camouflaging the animal and obscuring its features.

Recorded distribution in Britain and Ireland

Found on the South and West Coasts of the Britain and widespread in Ireland.

Global distribution

Pyura microcosmus ranges South from the British Isles in to the Mediterranean and Red Sea.


Generally, Pyura microcosmus attaches to hard substrates, including shells, stones and man made structures, in shallow protected areas. Pyura microcosmus is found in warm temperate seas in the northeastern Atlantic, Mediterranean and the Red Sea.

Depth range


Identifying features

  • Oral (inhalant) siphon terminal.
  • Orall tentacles flattened.
  • 7 branchial folds on each side of the body.
  • 1-3 gonads on right side.
  • Velum present in atrial (exhalant) siphon.

Additional information

No text entered



    1. Centre for Environmental Data and Recording, 2018. Ulster Museum Marine Surveys of Northern Ireland Coastal Waters. Occurrence dataset https://www.nmni.com/CEDaR/CEDaR-Centre-for-Environmental-Data-and-Recording.aspx accessed via NBNAtlas.org on 2018-09-25.

    2. Fenwick, 2018. Aphotomarine. Occurrence dataset http://www.aphotomarine.com/index.html Accessed via NBNAtlas.org on 2018-10-01

    3. NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.

    4. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2024-06-12


    This review can be cited as:

    Hosie, A.M. 2008. Pyura microcosmus A sea squirt. In Tyler-Walters H. and Hiscock K. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 12-06-2024]. Available from: https://www.marlin.ac.uk/species/detail/2217

    Last Updated: 20/10/2008