Nematomorph Parasitism of Crabs
Category 4 (Negligible Regulatory Significance in Canada)
Common, generally accepted names of the organism or disease agent
Parasitic juvenile nematomorphs in crabs.
Scientific name or taxonomic affiliation
Nectonema spp. (Nematomorpha: Nectonematoidea)
Bay of Fundy in eastern Canada and various coastal waters of the world where parasitic juveniles have been reported from crustaceans and free-swimming adults have been encountered.
Cancer borealis, Cancer irroratus, Pagurus acadianus, and other species of brachyuran and anomuran crabs and shrimp.
Impact on the host
Juveniles nematomorphs up to about 1 m in length, but usually less than 1.5 mm in diameter inhabit the body cavity. The size of individual Nectonema appears to be related to the size of individuals of the host species. Although there is little to no apparent tissue damage in most cases, evidence of gonad degeneration occurred in a few parasitized male C. irroratus. The route of infection is not known but it is suspected that on maturation of the nematomorph, natatory bristles develop and the "worm" exits the host by penetrating the membrane between the posterior margin of the cephalothorax and abdomen. The life expectancy of infected crustaceans is not known.
Gross Observations: White to creamy yellow thin worm-like organisms usually coiled in the posterior region of the haemocoel or along the hepatopancreas.
Methods of control
No known methods of prevention or control.
Leslie, H.A., A. Campbell and G.R. Daborn. 1981. Nectonema (Nematomorpha: Nectonematoidea) a parasite of decapod Crustacea in the Bay of Fundy. Canadian Journal of Zoology 59: 1193-1196.
Bower, S.M. (1996): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Nematomorph Parasitism of Crabs.
Date last revised: September 1996
Comments to Susan Bower
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