information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Sea lamprey (Petromyzon marinus)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.
Only coastal and marine records shown



Lampreys belong to a group of vertebrates known as Agnatha which means 'jawless fish'. Their mouth is a toothed circular sucking disk. They have long elongated eel-like bodies. They can also be recognised by their gills which open directly to each side of the head in the form of a line of seven gill holes behind the eye. The back and sides of Petromyzon marinus have a distinctly mottled colour pattern with a brown-yellow dorsal and lateral colouring. It usually reaches over 50 cm in length.

Recorded distribution in Britain and Ireland

Occurs offshore throughout the UK and Ireland, migrating upstream many British and Irish rivers in August to spawn .

Global distribution



Petromyzon marinus is a demersal and anadromous species found in a wide range of riverine and offshore habitats.

Depth range


Identifying features

  • Long eel-like body over 50 cm in length.
  • Brown-yellow dorsal and lateral colouring with black marblings.
  • Circular sucking disk for a mouth with sharp teeth.
  • Seven conspiculous gill holes in a line behind the eye.
  • Scales, paired fins and gill covers are absent.

Additional information

Relatively easily distinguished from the river lamprey Lampetra fluviatilis and the brook lamprey Lampetra planeri by its considerably larger size and distinctly mottled colour pattern (Igoe et al., 2004).

Listed by

Further information sources

Search on:


  1. Bristow, P., 1992. The Illustrated Encyclopedia of Fishes. Chancellor Press, London.

  2. Froese, R. & Pauly, D., 2007. Fishbase. A global information system on fishes. [On-line], 2008-02-18

  3. 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.]

  4. Igoe, F., Quigley, D.T.G., Marnell, F., Meskell, E., O'Connor, W. & Byrne, C., 2004. The sea lamprey Petromyzon marinus (L.), river lamprey Lampetra fluviatilis (L.) and brook lamprey Lampetra planeri (Bloch) in Ireland: general biology, ecology, distribution and status with recommendations for conservation. Biology and Environment. Proceedings of the Royal Irish Academy, Section B, 104B-S, 43-56.

  5. Kurz, I. & Costello, M.J., 1999. An Outline of the Biology, Distribution and Conservation of Lampreys in Ireland. In Marnell, F. (ed.), Irish Wildlife Manuals No5

  6. National Biodiversity Network (NBN) Atlas website. Available from:  Accessed 01 April 2017

  7. OBIS,  2018. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2018-09-19

  8. Schreiber, A. & Engelhorn, R., 1998. Population genetics of a cyclostone species pair, river lamprey (Lampetra fluviatilis L.) and brook lamprey (Lampetra planeri, Bloch). Journal of Zoological Systematics and Evolutionary Research, 36, 85-99


This review can be cited as:

Barnes, M.K.S. 2008. Petromyzon marinus Sea lamprey. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 19-09-2018]. Available from:

Last Updated: 27/03/2008