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Known introduction to Australia

Teredo navalis (naval shipworm)

General Information

picture of Teredo navalis

Frank Hecker, (email: Naturfoto.Hecker@t-online.de)

diagram of Teredo navalis

Diagram adapted from Hayward & Ryland 1996

Morphology

Minimum length 15 mm

Minimum size at maturity (Nair and Saraswathy, 1971).

Maximum length 1000 mm

1 m, maximum tube length observed by Mann and Gallager (1985). 58 cm Kristensen (1979).

Distribution Maps

  • World distribution and Australian distribution by regions - This map shows the world distribution of this species by IUCN bioregion.
  • Australian detections and potential range map - This map shows the Australian distribution of this species (as determined by port monitoring or other notification) and its potential range around the Australian coastline.
  • Description

    Linnaeus, 1758

    Teredo navalis is a bivalve specialised for boring into wood. It has a small shell that is used for burrowing and feeding, with fine ridges used for rasping away wood. Shell valves have three lobes separated by a single groove. The interior of the shell has a long curved process (styloid apophysis). Its body is elongated and protected by calcareous material secreted by the snail. Two siphons at the anterior end of the body protrude into the water for feeding, respiration and excretion. Classification of shipworms is based on siphonal pallets which block the entry to the burrow when conditions are unfavourable - pallets of T. navalis are paddle-shaped. T. navalis can create burrows up to 1m long.


    Taxonomy

    Phylum Mollusca
    Class Bivalvia
    Sub Class Heterodonta
    Suborder Myina
    Super Family Pholadoidea
    Family Teredinidae
    Genus Teredo

     

    Other names

    Common names naval shipworm
    common shipworm
    Atlantic shipworm

    Similar species

    Teredo pocilliformis
    Teredo calmani
    Teredo fragilis

     

    Adult temperature range Min 5.0 °C Max 30.0 °C
    Reproductive temperature range Min 15.0 °C
    Adult salinity range Min 5.0 ppt Max 35.0 ppt
    Reproductive salinity range
    Depth
    Habitat type Substrate
       Wood
    Tidal range
       Sub-tidal
    Vectors for introduction Vessels

    Please use the following citation for this material
    NIMPIS 2017, Teredo navalis general information, National Introduced Marine Pest Information System, viewed 23 June 2017 <http://www.marinepests.gov.au/nimpis>.

    Habitat

    T. navalis creates burrows in wood that can be up to one metre long. It can be found in boats, piers, driftwood and any other wooden structure from below the high tide mark. It is able to survive in temperatures up to 30 °C, however no growth occurs beyond 25 °C.

    Habitat classification

    For the purposes of NIMPIS, habitats have been divided into four categories: Hard, soft, water and organism. The habitat types assigned to these categories reflect the variety of substrata available for organisms to colonise. Habitat types listed for this species are those that have been recorded in the literature.

    Hard

    This category contains both natural and artificial habitats that are solid, fixed or permanent substrata. Species can reside on (e.g. attached externally) or within (e.g. boring into) the habitat type.

    • Wood

    Tidal Range

    • Sub-tidal

    Habitat survival parameters

    Minimum Maximum
    Adult temperature 5.0 °C
    In laboratory growth does not occur below this temperature (Kristensen, 1979). 15 °C minimum temp for normal activity (Nair and Saraswathy, 1971).
    30.0 °C
    Maximum temp that can be tolerated but 25 25 °C is maximum temp for activity (Nair and Saraswathy, 1971).
    Adult salinity 5.0 ppt
    (Nair and Saraswathy, 1971). However, Norman (1977) recorded very low densities at salinities of 8-11 ppt in Sweden.
    35.0 ppt
    Normal sea water (Nair and Saraswathy, 1971).
    Dissolved oxygen 1.0 mg/L
    Lowest oxygen level recorded but animals were still active (Nair and Saraswathy, 1971).
    N/a

    Reproduction and growth

    T. navalis has been recorded as hermaphrodites in a young population and then as separate sexes in adults. Spawning in T. navalis is temperature dependant. When sperm is released from one individual it is taken into the cavity of another individual with the inhalent water current. Fertilisation is internal, with young being brooded in the gills until they have developed a straight-hinged shell and velum. T. navalis is described as a short-term larviparous species, with young spending from two to four weeks in the plankton.
    Minimum reproductive temperature 15.0 °C (Nair and Saraswathy, 1971). However Grave(1928) noted spawning at 11 to 12 °C at Woods Hole.
    Maximum reproductive temperature N/a
    Cues N/a
    Strategy T. navalis is a short term larviparous species, young are released in the straight hinge stage, develop in the plankton to the pediveliger (Turner, 1971). Hermaphrodite (Nair and Saraswathy, 1971). Type 2 fertilisation internal, see notes.
    Season Near Denmark, peak settling coincides with the end of the period with the highest temperature. Kristensen (1979) indicated that pelagic larvae occurred at least from July to December. Peak settling from mid August to the end of September.

    Life cycle

    Age to maturity 42 days
    6 weeks, size at maturity is 15-20 mm long (Nair and Saraswathy, 1971).

    Please use the following citation for this material
    NIMPIS 2017, Teredo navalis reproduction and habitat, National Introduced Marine Pest Information System, viewed 23 June 2017 <http://www.marinepests.gov.au/nimpis>.

    Feeding Preferences

    Trophic status: herbivore

    Food is obtained by using the snail's sculptured shell to rasp away the wood. Particles are moved by cilia towards the mouth of T. navalis where the snail consumes the cellulose. Water is obtained through one of the siphons and used for both feeding and respiration.

    Food

    adult The shell is sculptured with file-like ridges which, when scraped against the anterior end of the burrow, rasp off particles of wood. These particles are carried, by cilia, to the mouth and are used as food. The siphons normally protrude through the minute opening of the burrow; the incurrent siphon takes in water for feeding and respiration, the excurrent one discharges waste and reproductive product (Turner, 1971). Growth enhancement in the presence of a phytoplankton supplement (in addition to wood) was not significant in this species (Mann and Gallager, 1985). Teredinid shipworms are associated with cellulolytic nitrogen-fixing bacterial endosymbionts enabling them to degrade wooden marine structures (Sipe et al., 1997). This bacteria appears to be acquired from the parents and not from the environment.
    larvae Larvae after release lead a pelagic life swimming actively and feeding on plankton (Nair and Saraswathy, 1971).

    Competitors

    Stage: adult Dense fouling accumulations over underwater surfaces can effectively inhibit the attack of both crustacean and molluscan borers. Undisturbed fouling inhibits settlement by serving either as a mechanical barrier for shipworm larvae or by utilizing larvae as a food. Of the different fouling organisms, the barnacles are perhaps the most effective agents hindering attachment. Fouled wood blocks have been shown to exhibit about one-ninth as much attack damage as clean panels (Nair and Saraswathy, 1971). The mode of attack by molluscan and crustacean borers is very different, and to some extent this enables the various borers to effectively share resources without serious competition. As a result crustacean borers may be found in close association with shipworms (Nair and Saraswathy, 1971). However, heavy crustacean attack may assist in the destruction of shipworms, probably because they expose the teredinid tubes, and thus cause mechanical damage or even death (Nair and Saraswathy, 1971).

    Predators

    Carnivorous snails have been observed consuming T. navalisTeredo. Sea birds, fish and mammals living in mangrove areas are known to feed on terenids. Indigenous Australians also utilised T. navalis as a food source, breaking apart bits of driftwood to access the snails.

    Please use the following citation for this material
    NIMPIS 2017, Teredo navalis feeding and predators, National Introduced Marine Pest Information System, viewed 23 June 2017 <http://www.marinepests.gov.au/nimpis>.

    Impacts

    T. navalis has a long history of causing damage to the shipping industry and to structures such as piers and marinas. Every year, shipworms cause millions of dollars damage all over the world. Early explorers were subjected to T. navalis, with the hulls of many ships suffering from shipworm rot. In 1990, a floating restaurant in the USA sank due to hull failure caused by shipworm burrowing activities. Many wooden waterfront structures such as houses, jetties and fences have been destroyed as a result of T. navalis. Many wooden waterfront structures such as houses, jetties and fences have been destroyed as a result of T. navalis.

    Vectors

    Descriptions of the vector types that are relevant to this species are displayed below.

    Vessels

    This class encompasses vectors associated with maritime transport and shipping activities. Vessels includes; commercial ships (e.g. tankers, container ships, ferries, barges), fishing vessels, recreational vessels, passenger vessels, drilling platforms and research vessels. An example of a vector from this class is ballast water,which has been found to transport up to 10 000 different species at any one time. Other vectors associated with this class include: dry ballast, biofouling community

    Biofouling Fouling communities are typically composed of encrusting or sessile species, however they can include mobile species. This vector can introduce species through a variety of means. Three examples are: (1) The spawning of a fouling species on a vessel in port and its successful settlement and establishment of a reproductive population; (2) The dislodgement of fouling species from a vessel in port through abrasion with wharf structures, ropes, etc., or through in water vessel hull cleaning (banned in Australia) or through high vessel speeds, etc.; and (3) The sinking of fouled vessels either deliberately or accidentally can introduce new species to a location. There are a variety of vectors capable of having a fouling community. Characteristics of a fouling community found on wooden boat hulls include: having a wood boring habit; a benthic sessile or encrusting stage; and mobile adults or larval stages. Fouling communities found within sea chests, anchor wells etc. often are mobile crevice occupying species or known obligate associate of fouling species and can escape into new locations.
    Ballast water The release of species in ballast water discharged from vessels. Various types and life stages of species can be transported in ballast water, including plankton, crustaceans, fish, larvae, eggs or cysts. Ballast water is used in commercial vessels to stabilise the vessel and is uploaded or discharged depending on the amount of cargo onboard. Ballast water as a vector also includes sediments that accumulate in the bottom of ballast tanks. Species that are able to survive within these sediments include those that have a resistant stage or resting cyst (eg. dinoflagellates) as well as adult stages of benthic organisms.
    Dry ballast The accidental release of species with solid ballast. Though solid ballast has predominantly been replaced by ballast water, it historically was used in vessels to stabilise the ship during transit. Dry ballast included rocks, sand, wood and other substrata collected from the foreshore and hence many intertidal species were also unintentionally included. When no longer required, this dry ballast was disposed of, usually overboard or onto the foreshore for subsequent use, releasing organisms to a new environment.
    Fisheries - accidental (not mollusc) The accidental translocation of species through aquaculture and fisheries activities. This vector includes the accidental release of live fish, crustaceans and molluscs (other than oysters) imported for human consumption, This vector also includes the accidental translocation of species attached to aquaculture gear (floats, cages, etc).
    Packing material The accidental release of species associated with seaweed (and other packing materials) for bait and fishery products. These packaging materials are often disposed of at sea by fishers, which can release organisms into the marine environment.
    Fisheries - accidental (products) The accidental translocation of species through aquaculture and fisheries activities. This vector includes the accidental release of live fish, crustaceans and molluscs (other than oysters) imported for human consumption, This vector also includes the accidental translocation of species attached to aquaculture gear (floats, cages, etc).

    Please use the following citation for this material
    NIMPIS 2017, Teredo navalis impacts and vectors, National Introduced Marine Pest Information System, viewed 23 June 2017 <http://www.marinepests.gov.au/nimpis>.

    Additional Information

    General Notes

    adult T. navalis broods its young in the gills until they have developed a straight-hinged shell and a velum. This is a short-term larviparous species; the young spend from 2 to 4 weeks in the plankton, where ther feed and develop into pediveligers.
    Larviparous marine shipworms are or may become world-wide in distribution within the limits of their salinity and temperature tolerances. The probable reason is that the larvae are carried in an envelope of quiet water created by the fouling organisms on the hull and when they are ready to settle the parent wood is available. During the slow voyages of sailing-ship days it was probably the second or third generation that produced the larvae infecting new wood in a foreign port (Turner, 1971).
    Adult teredinids, by closing their burrows, can withstand wide ranges in salinity and even desiccation for periods of about a month (Turner, 1971).
    T. navalis displays functional hermaphroditism, with recurrent functional sex inversion. Males constitute 30-50% of the adult population with a preponderance of functional males in young populations. Later a greater part of the individuals in these populations become females, these animals having the ability to revert back to the male phase. The transition from female to male can occur abruptly during the breeding season as well as during the recuperation period (Nair and Saraswathy, 1971). Some individuals remain in their first male phase for a long time or even indefinately and these animals have been refered to as true males (Nair and Saraswathy, 1971).
    Fertilisation in T. navalis is described as type 2: sperm discharged into the water by one individual may be taken in through the inhalant siphon of another, fertilization taking place in the epibranchial cavity (Nair and Saraswathy, 1971).
    larvae T. navalis broods its young in the gills until they have developed a straight-hinged shell and a velum. This is a short-term larviparous species; the young spend from 2 to 4 weeks in the plankton, where they feed and develop into pediveligers. When liberated into the sea water they are typical lamellibranch veligers, vigorous and hardy. The approximate age of embryos can be estimated by their color since they gradually change from white to a dark muddy gray during development (Grave, 1928).
    egg The oviducts open into the suprabranchial chambers which are extensive and serve as brood pouches. When the eggs are extruded they are retained in the suprabranchial chambers for a period of two or three weeks, during which time they pass through the early stages of development (Grave, 1928). The embryo is not parasitic upon the mother, but the egg will not develop outside the gill chamber (grave, 1928).

    Identification Notes

    adult Shell more or less globose, gaping at both ends; valves trilobate, concentrically striate, divided by a single transverse groove; hinge margins inflexed anteriorly; interior with a long, curved process, the styloid apophysis. Pallets paddle-shaped or leaf-shaped, having the calcareous portion unbroken in contour (Cotton, 1961). Pallets approximately paddlelike (Kozloff, 1996).
    larvae Initially larvae are white, however, the color darkens soon after they reach 100 µm in length. The larvae of advanced stages of T. navalis do not develop an eye, the foot is extremely slender and worm-like and they attach themselves to the substratum by a byssus. T. navalis have been found not to develop a foot, otocyst nor gill filaments before larvae reach the size of 215 X 200 µm, however, these structures may appear at a size at least 15 µm smaller (Nair and Saraswathy, 1971).
    egg The egg of T. navalis is comparatively small and white in color (Grave, 1928).

    Similar Species

    adult In Australia three similar species occur: T. pocilliformis, T. calmani and T. fragilis (Cotton, 1961).

    Please use the following citation for this material
    NIMPIS 2017, Teredo navalis additional information, National Introduced Marine Pest Information System, viewed 23 June 2017 <http://www.marinepests.gov.au/nimpis>.

    References

    • Cai, Lizhe, Li, Fuxue (1990) Temporal and spatial variations of quantity of shipworm Teredo navalis in Xiamen Harbour. Journal of Oceanography (Taiwan) 9, pp212-216.

    • Calvo, G.W. (1984) Attack of boring organisms on six types of woods in marine waters. Contributions. Department of Oceanography. University of Republica 1, pp19.

    • Cotton, B.C. (1961) South Australian Mollusca. W.L. Hawkes, Government Printer,,.

    • Douglas, W.S. (1981) The preservative treatment of pine poles for use in the intertidal zone of warm waters. South African Forestry Journal 116, pp64-68.

    • Ghobashy, A.F.A., Hassan, A.K. (1980) Notes on the Wood Boring in the Suez Canal. Marine Biology , pp93-98.

    • Grave, B.H. (1928) Natural history of shipworm, Teredo navalis, at Woods Hole, Massachusetts. Biological Bulletin (Woods Hole) 55, pp260-282.

    • Hayward, P.J., Ryland, J.S. (1996) Handbook of the Marine Fauna of North-West Europe. Oxford University Press,,.

    • Hoagland, K. (1986) Effects of temperature, salinity, and substratum on larvae of the shipworms Teredo bartschi Clapp and T. navalis Linnaeus (Bivalvia: Teredinidae). American Malacological Bulletin 4, pp89-99.

    • Junqueira, A.O.R., Silva, S.H.G., Silva, M.J.M. (1989) Evaluation of the infestation and diversity of Teredinidae (Mollusca Bivalvia) along the coast of Rio de Janeiro State, Brazil. Memorias. Instituto Oswaldo Cruz 84, pp275-280.

    • Kozloff, E.N. (1996) Marine Invertebrates of the Pacific Northwest. University of Washington Press,,.

    • Kristensen, E.S. (1979) Observations on growth and life cycle of the shipworm Teredo navalis L. (Bivalvia, Mollusca) in the Isefjord, Denmark. Ophelia 18(2), pp235-242.

    • Mann, R., Gallager, S.M. (1985) Growth, morphometry and biochemical composition of the wood boring molluscs Teredo navalis L., Bankia gouldi (Bartsch), and Nototeredo knoxi (Bartsch) (Bivalvia: Teredinidae). Journal of Experimental Marine Biology and Ecology 85, pp 229-251.

    • Martinez, J.C. (1982) Comparative study of bacterial populations isolated from the digestive tract of Teredo navalis L. (Teredinidae Bivalvia) and the surrounding sea water. IN: Second symposium on marine microbiology, Vol 13 ,, pp91-96.

    • Nair, N.B., Saraswathy, M. (1971) The biology of wood-boring teredinid molluscs. Advances in Marine Biology 9, pp335-509.

    • Norman, E. (1977) The geographical distribution and the growth of the wood-boring molluscs Teredo navalis L., Psiloteredo megotara (Hanley) and Xylophaga dorsalis (Turton) on the Swedish west coast. Ophelia 16(2), pp233-250.

    • Paula Mueller, A.C., da Cunha Lana, P. (1987) Geographic distribution patterns of Teredinidae (Bivalvia: Mollusca) from the coast of Parana State (SE Brazil). Cienc Cult 39(12), pp1175-1177.

    • Sakai, A., Sekiguchi, H. (1992) Identification of planktonic late stage larval and settled bivalves in tidal flat. Bulletin. Japanese Society of Fisheries and Oceanography, Suisan Kaiyo Kenkyu 56, pp410-425.

    • Sipe, A.R., Wilbur, A.E., Cary, S.C. (1997) Molecular determination of symbiont transmission strategies in wood-boring bivalves (Fm. Teredinidae). Journal of Shellfish Research 16(1), pp357.

    • Soldatova, I.N. (1987) Functional role of some invertebrates in the Sea of Azov ecosystem. Feeding of Marine Invertebrates and its Significance in Formation of Communities. 1987, pp75-83.

    • Tsikhon Lukanina,E.A. (1976) Nutrition of Black Sea bivalve mollusks. Soviet Journal of Marine Biology 2, pp168-174.

    • Tsunoda,K., Nishimoto,K. (1978) Growth rates of the shipworm Teredo navalis - L. at Naruto, Tokushima Pref., Japan. Material und Organismen (Berlin) 13, pp287-296.

    • Turner, R.D. (1971) Australian shipworms. Australian Natural History 17(4), pp139-145.

    • Wagh, A.B. and Raveendran, T.V. (1987) An account on marine wood-boring organisms of offshore waters of Bombay High, India. Advances in Aquatic Biology and Fisheries. 1987, pp405-412.

    • Yoshinaga, K. (1999) Sessile animals on an artificial fish reef with pine tree. Men. Fac. Fish. Kagoshima. Univ. 48, pp7-10.

    • Yulianda, F. (1996) Boring marine bivalves and a sphaeromatid (Crustacea) attacking wood for boat building - Identification and intensity, Java, Indonesia. Phuket Marine Biological Center Special Publication 16, pp319-322.

    • Yulianda, F. (1997) Density of boring marine bivalves in pieces of wood inside and outside Pelabuhan Ratu Harbour, West Java, Indonesia. Phuket Marine Biological Center Special Publication 17(1), pp151-153.