Rev: 01/04/2023

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                          Anisakis Dujardin, 1845

Type species of the genus: Anisakis dussumierii (Beneden, 1870) Baylis, 1920 (sensu Mozgovoy, 1953).


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Morphology and Anatomy:

Ref: Safonova et al. 2021

Anisakis simplex may reach a length of 2-4 cm.





Body size range for the species of this genus in the database - Click:
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Nematodes of the genus Anisakis (Nematoda: Anisakidae) are parasites of marine organisms. The life cycle of these nematodes requires marine mammals, mainly cetaceans, as the definitive hosts, and crustaceans, fish, and cephalopods as intermediate or paratenic hosts (Klimpel and Palm, 2011).

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Biology and Ecology:

Humans are accidental hosts due to ingestion of raw or undercooked fish containing the third infective-stage larvae. Human anisakiasis patients suffer from abdominal pain, nausea, vomiting, and/or diarrhea (Dorny et al., 2009).


The following detailed descriptions and lifecycles of nematodes associased with Anisakiasis are provided courtesy of CDC, the Centers for Disease Control and Prevention

Causal Agents

Anisakiasis is caused by the ingestion of larvae of several species of ascaridoid nematodes (roundworms), which are sometimes called herringworm, codworm, sealworm�, in undercooked marine fish. Known human-infecting anisakid species include members of the Anisakis simplex complex [A. simplex sensu stricto, A. pegreffii, A. berlandi (=A. simplex C)], the Pseudoterranova decipiens complex (P. decipiens sensu stricto, P. azarasi, P. cattani, and others), and the Contracecum osculatum complex. Recent genetic studies have revealed high diversity within these anisakid groups, suggesting additional cryptic species are likely represented in zoonotic infections.



Adult stages of anisakid nematodes reside in the stomach of marine mammals, where they are embedded in the mucosa in clusters. Unembryonated eggs produced by adult females are passed in the feces of marine mammals image . The eggs become embryonated in water, undergoing two developmental molts image , and hatch from the eggs as free-swimming ensheathed third-stage (L3) larvae image . These free-swimming larvae are then ingested by crustaceans image . The ingested larvae grow within the crustacean hemocoel, and become infective to fish and cephalopod paratenic hosts. After preying upon infected crustaceans, the digested L3 larvae migrate from the paratenic host intestine into the abdominal cavity, and eventually to the tissues of the mesenteries and skeletal muscle. Through predation, tissue-stage L3 larvae can be transmitted among paratenic hosts image . Fish and squid maintain L3 larvae that are infective to humans and marine mammals image .

When fish or squid containing third-stage larvae are ingested by definitive host marine mammals, the larvae molt twice and develop into adult worms image . After ingestion by humans, the anisakid larvae penetrate the gastric and intestinal mucosa, causing the symptoms of anisakiasis image .


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Life Cycle:

For Ecophysiological Parameters for this genus, click 
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Ecosystem Functions and Services:


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Dorny, P., Praet, N., Deckers, N. and Gabriel, S. 2009. Emerging food-borne parasites. Veterinary Parasitology 163:196-206.

Klimpel, S. and Palm, H. W. 2011. Anisakid nematode (Ascaridoidea) life cycles and distribution: Increasing zoonotic potential in the time of climate change?  In Mehlhorn, H. (Ed.), Progress in parasitology. Parasitology research monographs, Vol. 2 Springer, Berlin, pp. 201-222.

Safonova, A.E., Voronova, A.N., Vainutis, K.D. 2021. First report on molecular identification of Anisakis simplex in Oncorhynchus nerka from the fish market, with taxonomical issues within Anisakidae. J. Nematology 53 :| DOI: 10.21307/jofnem-2021-023

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Copyright © 1999 by Howard Ferris.
Revised: January 04, 2023.