Great shipworm (Teredo navalis)

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



Teredo navalis is a bivalve mollusc but appears worm-like due to its elongated body and reduced trilobed shell, which is specialised for wood boring. The shell is white in colour with its outer most layer (periostracum) light brown. The shell can be up to 2cm long and covers only the anterior end of the long, soft body. The valves of the shell are divided into different regions with various sculptures. The beaks are situated near the anterior end of the shell. The soft worm-like body is light brown in colour and up to 15 cm in length. It lies in a calcareous tube up to 60 cm long and 0.8 cm in diameter. The thin tube has a septa (dividing wall) near the opening. There are two small siphons at the posterior end of the body that are withdrawn and closed off by a calcareous pair of paddle shaped accessory plates (pallets), each off white in colour and up to 0.5 cm long.

Recorded distribution in Britain and Ireland

This species is locally common and may be found on all British coasts. It has been recorded from the south east to south west coasts.

Global distribution



This wood boring bivalve is the most common and destructive ship worm. It is not easily recognizable as a bivalve mollusc, boring permanent tubes into wooden structures such as piers, boat hulls and drift wood.

Depth range


Identifying features

  • Small white shell.
  • Light brown soft body tissues.
  • Reduced trilobed shell up to 2 cm in length.
  • Tube up to 60 cm long and 0.8 cm in diameter.
  • Anterior and posterior lobes of the shells are similar in size.
  • Shells triangular in shape.

Additional information

The trilobed, heavily ridged shells halves of Teredo navalis are used to drill through wood forming characteristic, winding burrows that are lined with chalky deposits. These burrows can be seen when the wood is split apart. The small holes can be up to 1 cm in diameter.

Listed by

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  1. Board, P.A., 1963. Teredo investigations: Rivers Stour and Orwell. Laboratory Reports. Central Research Laboratories, (RD-L-N 119-63),

  2. Board, P.A., 1963b. Teredo investigations: River Hamble. Laboratory note: Central Electricity Research Laboratories, (RD-L-N 45-63),

  3. Board, P.A., 1963c. Teredo investigations: River Medway. Laboratory note: Central Electricity Research Laboratories, (RD-L-N 26-63),

  4. Board, P.A., 1969. The effect of a warm effluent on the biology of shipworms. Part 1. Preliminary studies of the shipworms Teredo navalis L. and Lyrodus pedicellatus Quatrefages. Laboratory note: Central Electricity Research Laboratories, (1/69), 10pp.

  5. Coughlan, J., 1977. Wood-borer survey, Southamptom Water 1976, with proposals for future monitoring. Laboratory note: Central Electricity Research Laboratories, (RD-L-N 145-77), 13pp.

  6. Coughlan, J.; Fleming, J.M., 1969. Observations on the growth of Teredo sp. from the warm and cold water tanks at Bradwell. Laboratory note: Central Electricity Research Laboratories, (21-69), 10pp.

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

  8. Gibson, R., Hextall, B. & Rogers, A., 2001. Photographic guide to the sea and seashore life of Britain and north-west Europe. Oxford: Oxford University Press.

  9. Hayward, P., Nelson-Smith, T. & Shields, C. 1996. Collins pocket guide. Sea shore of Britain and northern Europe. London: HarperCollins.

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

  11. 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.]

  12. Perkins, E.J., 1961. The occurrence of the shipworm (Teredo) in the River Blackwater estuary. Laboratory note: Central Electricity Research Laboraties, (RD-L-N 97-61),

  13. Tebble, N., 1976. British Bivalve Seashells. A Handbook for Identification, 2nd ed. Edinburgh: British Museum (Natural History), Her Majesty's Stationary Office.

  14. Wood, E. (ed.), 1988. Sea Life of Britain and Ireland. Marine Conservation Society. IMMEL Publishing, London


  1. Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) records for Great Britain and Ireland. Occurrence dataset: accessed via on 2018-09-25.

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

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

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

  5. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-05-18


This review can be cited as:

Rowley, S.J. 2005. Teredo navalis Great shipworm. 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 18-05-2024]. Available from:

Last Updated: 22/07/2005