Blue jellyfish (Cyanea lamarckii)

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



The bell can grow up to 30 cm in diameter. Hollow marginal tentacles arise from the underneath the bell. These are arranged in eight horseshoe or rectangular shaped groups each with 40-60 tentacles. Beneath the bell is a short thick manubrium merging onto four wide membranous and folded curtain like oral lips. The oral lips may be yellowish and fade to white at their extremities. It has thick and frilly oral arms that are slightly shorter than the diameter of the bell. The sense organs in the bell are protected by a long exumbrellar extension which forms a hood. Its colour varies from translucent through pale yellow, pale brown, pale grey to light blue or purple. In faintly coloured species the blue tends to outline the pattern of the internal sculpting of the bell (Russell, 1970). It has four interradial folded gonads that hang freely downwards beneath the bell surface.

Recorded distribution in Britain and Ireland

Cyanea lamarckii occurs in coastal waters all around the British Isles. It has been recorded from the Shetland Islands, the Orkneys, along the east coast of England, Dartmouth in the south and up through the west coasts of England and Wales.

Global distribution



Cyanea lamarckii is a pelagic species.

Depth range


Identifying features

  • Umbrella or saucer shaped.
  • Uniformly fairly thick jelly, that thins suddenly at the bell margin.
  • Clusters of stinging cells (nematocysts) are prominent on the upper surface of the bell.
  • The margin of the bell has eight groups of 40-60 tentacles.

Additional information

Cyanea lamarckii is similar to Cyanea capillata. However, Cyanea capillata is the larger of the two as it can grow up to 50 cm in diameter and is deep reddish brown in colour. It also has more tentacles with 70-150 tentacles in each of the eight groups of tentacles.

Very young specimens are colourless but they take on colour as they mature.

Listed by

- none -



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    2. Cofnod – North Wales Environmental Information Service, 2018. Miscellaneous records held on the Cofnod database. Occurrence dataset: accessed via on 2018-09-25.

    3. Environmental Records Information Centre North East, 2018. ERIC NE Combined dataset to 2017. Occurrence dataset: accessed via on 2018-09-38

    4. Fenwick, 2018. Aphotomarine. Occurrence dataset Accessed via on 2018-10-01

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    6. Fife Nature Records Centre, 2018. St Andrews BioBlitz 2015. Occurrence dataset: accessed via on 2018-09-27.

    7. Kent Wildlife Trust, 2018. Kent Wildlife Trust Shoresearch Intertidal Survey 2004 onwards. Occurrence dataset: accessed via on 2018-10-01.

    8. Marine Conservation Society, 2018. UK Jellyfish Sightings from 2003 to 2015. Occurrence dataset: accessed via on 2018-10-01.

    9. National Trust, 2017. National Trust Species Records. Occurrence dataset: accessed via on 2018-10-01.

    10. NBN (National Biodiversity Network) Atlas. Available from:

    11. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-04-25

    12. Outer Hebrides Biological Recording, 2018. Invertebrates (except insects), Outer Hebrides. Occurrence dataset: accessed via on 2018-10-01.

    13. Suffolk Biodiversity Information Service., 2017. Suffolk Biodiversity Information Service (SBIS) Dataset. Occurrence dataset: accessed via on 2018-10-02.

    14. The Wildlife Information Centre, 2018. TWIC Biodiversity Field Trip Data (1995-present). Occurrence dataset: accessed via on 2018-10-02.


    This review can be cited as:

    Sabatini, M. 2008. Cyanea lamarckii Blue jellyfish. 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 25-04-2024]. Available from:

    Last Updated: 29/04/2008