A nudibranch (Hancockia uncinata)

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



Hancockia uncinata is a pale green or pink nudibranch with scattered white spots and up to 9 pairs of small, hand shaped cerata. Adults may reach lengths of up to 14 mm. The tips of the rhinophores are unusual in that they are swollen and have longitudinal lamellae. The oral vein extends into 2 lateral flaps, each with 3-4 finger like projections.

Recorded distribution in Britain and Ireland

A scarcely recorded species known to be present in Devon, Galway, Donegal and west Scotland.

Global distribution

Most records are from the Bay of Biscay, but also recorded from the Mediterranean Sea, France, Spain and Italy.


Hancockia uncinata feeds on the tiny hydroid Clytia hemisphaerica (= Clytia johnstoni) which grows over other hydroids or on algae.

Depth range


Identifying features

  • Small, hand like cereta
  • Swollen tipped rhinophores with sheaths and longitudinal lamellae

Additional information

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  1. Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]

  2. Picton, B. E. & Morrow, C.C., 1994. A Field Guide to the Nudibranchs of the British Isles. London: Immel Publishing Ltd.

  3. Thompson, T. E. & Brown, G. H., 1976. British Opisthobranch Molluscs. London: Academic Press. [Synopses of the British Fauna, no. 8.]

  4. Thompson, T.E., 1972. Eastern Australian Dendronotoidea (Gastropoda: Opisthobranchia). Zoological Journal of the Linnean Society, 51(1), 63-77

  5. WoRMS 2007. The World Register of Marine Species (WoRMS). http://www.marinespecies.org, 2008-10-31


  1. Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) data for Great Britain and Ireland - restricted access. Occurrence dataset: https://doi.org/10.15468/4bsawx accessed via GBIF.org on 2018-09-25.

  2. Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) records for Great Britain and Ireland. Occurrence dataset: https://doi.org/10.15468/aurwcz accessed via GBIF.org on 2018-09-25.

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

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

  5. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2024-05-20


This review can be cited as:

Sweet, N. A. 2008. Hancockia uncinata A nudibranch. 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 20-05-2024]. Available from: https://www.marlin.ac.uk/species/detail/174

Last Updated: 24/07/2008