Biodiversity & Conservation

Great shipworm - Teredo navalis

Teredo navalis

Image Steve Trewhella - Driftwood bored by the shipworm Teredo navalis. Image width ca 18 cm.
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Distribution map

Teredo navalis recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

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Teredo navalis is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Mollusca Snails, slugs, mussels, cockles, clams & squid
Class Bivalvia Clams, cockles, mussels, oysters, and scallops
Authority Linnaeus, 1758
Recent synonyms None
Map icon 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.
Habitat information icon Habitat information 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.
Text page icon Description 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 There are two small siphons at the posterior end of the body that are withdrawn and closed off by a calcareous pair of paddle shaped accessory plates (pallets), each off white in colour and up to 0.5 cm long.
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 icon 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.

This review can be cited as follows:

Sonia Rowley 2005. Teredo navalis. Great shipworm. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 04/02/2012]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=4447>