MarLIN

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

An acorn barnacle (Adna anglica)

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

Researched byAnna Neish Refereed byAdmin
Authority(Sowerby, 1823)
Other common names- SynonymsPyrgoma anglica

Summary

Description

It has a conical shell on a circular cup-shaped base and can reach up to 6 mm in diameter. It is pink in colour and there are no structures on the outside but the shell is marked with longitudinal striations. The opening at the top (operculum) is depressed and the whole organism has a vase-like appearance.

Recorded distribution in Britain and Ireland

Restricted to the south west of the British Isles, from Exmouth, south Devon to Elwill Bay in north Devon. Also found on the south west coasts of Pembrokeshire and Ireland but does not replicate the distribution of its host as it is a warm water species.

Global distribution

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Habitat

Megatrema anglicum lives in association with corals where it attaches to their calcareous skeletons. Megatrema anglicum is found mainly on Caryophyllia smithii, and was found on 30-50% of corals collected in the south west (Hiscock & Howlett, 1976) but it has also been found on at least 8 genera including the British species: Leptopsammia pruvoti, Balanophyllia regia and Hoplangia durotrix. It is on the shore in shaded places to 50 m and less often in sheltered waters.

Depth range

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Identifying features

  • A conical shell up to 6mm in diameter with a cup shaped base.
  • Longitudinal striations on the outer shell.
  • Depressed operculum.
  • Found only attached to corals, usually Caryophyllia smithii.
  • Attached near the living tissues of the corals.

Additional information

Another barnacle, Verruca stroemia may be found low down on the column of Caryophyllia smithii but only Megatrema anglicum has succeeded in adapting to settle on the living region of the coral. Its larvae appear unaffected by the coral defence system, and a heavy infestation of Megatrema anglicum may hamper the coral's food gathering ability (Rees, 1962).

Listed by

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Further information sources

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Bibliography

  1. Fish, J.D. & Fish, S., 1996. A student's guide to the seashore. Cambridge: Cambridge University Press.

  2. Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.

  3. Hiscock, K. & Howlett, R. 1976. The ecology of Caryophyllia smithii Stokes & Broderip on south-western coasts of the British Isles. In Underwater Research (ed. E.A. Drew, J.N. Lythgoe & J.D. Woods), pp. 319-344. London: Academic Press.

  4. Moyse, J., 1971. Settlement and growth pattern of the parasitic barnacle Pyrgoma anglicum. Fourth European Marine Biology Symposium. Ed. D.J. Crisp.

  5. Rees, W.J., 1962. The distribution of the coral Caryophyllia smithii and the barnacle Pyrgoma anglicum in British waters. Bulletin of the British Museum (Natural History) (Zoology), 9, 401-418.

Citation

This review can be cited as:

Neish, A.H. 2003. Adna anglica An acorn barnacle. 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. Available from: http://www.marlin.ac.uk/species/detail/1884

Last Updated: 26/11/2003