April 22 - Anisakis nascettii

Anisakid nematodes are well-known as gastrointestinal parasites of various marine mammals. They utilise crustaceans like krill and amphipods as intermediate hosts, and when these crustaceans are eaten by fish or squid, they migrate into the muscle tissue where they await ingestion by a marine mammals. Humans can become accidental host of anisakids when they eat raw or undercooked fish or squid. While the worm cannot survive in humans, they can induce a severe allergic reaction.

There are many species of anisakid nematode and recently a new species, Anisakis nascettii, was found in an Andrews' Beak Whale (Mesoplodon bowdoini) stranded off the east coast of South Island, New Zealand. Using morphological and molecular identification, a team of researchers was able to match the worms found in the New Zealand-stranded whale to specimen found in beaked whales on the coast of South Africa and Australia. They also found that those worms actually belong to an undescribed species that has only ever been recorded as larval stages in squid. This goes to shows that while these days, the prospect of discovering a new species of large vertebrates is very unlikely, new species of parasites are being uncovered literally everyday!



Reference:
Mattiucci, S., Paoletti, M., Webb, S.C. (2009). Anisakis nascettii n. sp. (Nematoda: Anisakidae) from beaked whales of the southern hemisphere: morphological description, genetic relationships between congeners and ecological data. Systematic Parasitology, 74:199-217.

Contributed by Tommy Leung.