Chesapeake Bay Introduced Species Database

Teredo navalis

Common name(s):
Naval Shipworm
Naval Shipworms are bivalves (like clams) that look like worms. They don?t use their shell for protection; rather they use it as a tool to burrow into wood. They live in the burrow they create in the wood, poking their heads out to feed. Historically these shipworms made their homes in the hulls of wooden ships and traveled the world. Because wooden ships have moved these species around the world for so long, it is difficult to say where they originated and where they were introduced. We believe Naval Shipworms are introduced to the East Coast because reports of this species were confined to ships and shipwrecks, but were absent in natural areas and in wood of a 5,000 yr-old fishweir in Boston, through a similar native species (Bankia gouldi) was found. Naval Shipworms were first seen in the Elizabeth River in 1878 under in debris from a wharf. In the late 1940s and early 1950s, they were reported in Chincoteague Bay, Ocean City MD, and Hampton Roads, Norfolk and Portsmouth VA.
Image courtesy of Wiki Commons.

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Environmental Tolerances

For Survival
For Reproduction
Temperature (ºC)
0 30 11 null
Salinity (‰)
5 45 9 null
null null    
Salinity Range

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Age and Growth

Minimum Adult Size (mm)
null 50
Typical Adult Size (mm)
null 200
Maximum Adult Size (mm)
null 400
Typical Longevity (yrs)
null 1.5
Maximum Longevity (yrs)
null 2

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Reproductive Season
April --- September
Typical Number of Young
per Reproductive Event
Sexuality Mode(s)
Mode(s) of Asexual Reproduction
Fertilization Type(s)
More than One Reproductive
Event per Year
Reproductive Strategy
Egg/Seed Form

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Minimum Typical Maximum
Egg/Seed Development Time (days)
null 5 null
Larval/Seed Development Period (days)
11 28 35
Male Maturation Age (yrs)
null 0.12  
Female Maturation Age (yrs)
null 0.135  
Larval/Seed Form  

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Locomotion and Abundance in Chesapeake

planktonic rare
sessile, floating rare
sessile, floating rare

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Habitat Preferences

Primary Horizontal Habitats
unstructured; coarse woody debris; marinas and docks coarse woody debris; marinas and docks coarse woody debris; marinas and docks
Secondary Horizontal Habitats
Reproductive Horizontal Habitats
n/a n/a unstructured; coarse woody debris; marinas and docks
Vertical Habitats
planktonic epibenthic epibenthic
Substrate Type
none wood; piers wood; piers
Tidal Height Location
subtidal low intertidal; subtidal subtidal; low intertidal
Wave Exposure
heavy; moderate; low; protected
Water Flow
stagnant; slow; fast

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Trophic Interactions

Trophic Status
planktotrophic suspension feeder; herbivore suspension feeder; herbivore
Common Food/Prey Items
phytoplankton wood; phytoplankton wood; phytoplankton
Common Competitors
Common Consumers
Minchinia teredinis; Nereis succinea; Euplana gracilis; Stylochus ellipticus Minchinia teredinis; Nereis succinea; Euplana gracilis; Stylochus ellipticus

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Life History: Environmental Tolerances: Oxygen- Teredo navalis can survive anoxic conditions for extended periods by using stored glycogen, and can survive 6 weeks sealed in burrows, but prolonged low O2 can interfere with feeding and reduce infestations (Richards et al. 1984).

Reproduction: Reproductive Season- The season of larval release was April-September, in Barnegat Bay (Richards et al. 1984); and May-October, Woods Hole (Grave 1928). Typical Number of Young per Reproductive Event - 'One million to five millions' of larvae can be brooded per worm (Grave 1928). Fertilization Type(s)- Sperm are released into the water, and fertilized in the epibranchial cavity (Richards et al. 1984). We have classified this as 'Outcross-internal' since fertilization occurs inside the body.

Development: Larval Period Length- The period from larval release to settlement is reported as 3-4 weeks, in Barnegat Bay NJ (Richards et al. 1984) and 4-5 weeks, in Woods Hole MA (Grave 1928). The 'average length of veliger life is constant for a given species at a given locality, being shorter in tropical water than in colder areas. If wood is not available, the larval life may continue for several days, though the ability to penetrate wood apparently decreases with the aging of the larvae' (Lane 1959b, cited by Turner 1971). Maturation Age- Teredo navalis is a protandric hermaphrodite, and becomes sexually mature as a male withn 6 weeks of settlement, and then switches to functioning as a female by 8 weeks (Grave 1928).

Locomotion and Abundance: Abundance- Teredo navalis is rare in the Bay proper, but is common on the adjacent Atlantic Coast (Chincoteague, and other Bays) (Scheltema and Truitt 1956; Wass et. al. 1972).
Community Ecology: Trophic Interactions: Consumers - Minchinia teredinis is a parasite, related to Haplosporidium nelsoni (MSX) of oysters, which heavily infects Teredo navalis in Barnegat Bay and probably elsewhere (Hillman et al. 1990; Richards et al. 1984). Shipworms are vulnerable to metazoan predators mainly when the wood they are in disintegrates (Hoagland 1983).

This data was last modified on Thursday, September 29th, 2005.
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