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Marine Habitat Classification


What is it?

The Marine Habitat Classification for Britain and Ireland is one of the most comprehensive seafloor habitat classification systems in the world. It has evolved through review of other classifications, analysis of data and contributions from a wide range of marine scientists and conservations bodies.

The classification lists all seafloor habitats currently known to occur in UK waters. These habitats are organised in a hierarchy whereby each level introduces more detail.

What do we mean by habitat?

In any place on the shore or seabed, a suite of species will occur, each adapted to the particular environmental conditions of that place, such as the conditions of an intertidal mudflat. Where such a suite of species occurs in other locations under similar environmental conditions, it can be defined as a community (or association or assemblage) of species which is occurring within a particular habitat type. The collective term biotope is now in common usage to encompass both biotic and abiotic elements.

Why is it useful?

The classification is widely used by Government bodies, academic institutions, the private and charity sectors as a system for the consistent description of habitat types. It provides:

  • The ability to map habitats to assess their extent and geographical distribution;
  • Categories for the assessment of the state (condition and trend) of marine biological communities and the basis for monitoring sample allocation;
  • The ability to assess the nature conservation value of habitats at specific locations, such as in the identification of marine protected areas and the licensing of industry activities;
  • The ability to assess the extent of protection afforded to habitat ‘stock’ by existing and proposed marine protected areas and wider measures.


The first official release of the classification (version 97.06) was developed by JNCC's Marine Nature Conservation Review as part of the EC Life Nature-funded BioMar project (Connor et al. 1997 a, b). Version 04.05 was released following an update in 2004 (Connor et al., 2004). Version 15.03 was released in 2015 following the addition of a deep-sea section (Parry et al., 2015). The current version (22.04) was released in 2022 following an update to the sublittoral sediment section.

Current developments

After the release of the new version 22.04, we are going to work on an update to the rock part of the classification system. This project aims to improve the consistency of classification by reviewing the validity existing biotopes and adding any new biotopes identified from recent survey data. The project also aims to develop a less subjective, data-driven approach for assigning biotopes. The classification will be updated section by section in the following order: littoral and infralittoral rock, and circalittoral rock. See the two-page project summary document on the Resources page.

How to cite

Version 22.04 of the classification revises the sublittoral sediment section; therefore superseding version 15.03, 04.05, 97.06 and 03.02.

This online classification should be cited as:

JNCC (2022) The Marine Habitat Classification for Britain and Ireland Version 22.04. [Date accessed]. Available from:

Information from the shallower section (up to sublittoral sediment, taken from Version 04.05) be cited as the report accompanying Version 04.05, as follows:

Connor, D.W., J.H. Allen, N. Golding, K.L. Howell, L.M. Lieberknecht, K.O. Northen and J.B. Reker (2004) The Marine Habitat Classification for Britain and Ireland Version 04.05 ISBN 1 861 07561 8. In: JNCC (2022) The Marine Habitat Classification for Britain and Ireland Version 22.04. [Date accessed]. Available from:

Information from the deep-sea section (added in March 2015) should be cited as the report accompanying the deep-sea section, as follows: 

Parry, M.E.V., K.L. Howell, B.E. Narayanaswamy, B.J. Bett, D.O.B. Jones, D.J. Hughes, N. Piechaud, T.D. Nickell, H. Ellwood, N. Askew, C. Jenkins and E. Manca (2015) A Deep-sea Section for the Marine Habitat Classification of Britain and Ireland. JNCC report 530. ISSN 0963 8901 In: JNCC (2022) The Marine Habitat Classification for Britain and Ireland Version 22.04. [Date accessed]. Available from:

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