Thursday, 12 March 2015

Creature 163: Pomphorhynchus laevis

A worm that wants to be eaten.
Pomphorhynchus laevis is a parasitic worm with multiple hosts.

It has an intermediate host the fresh water amphipod Gammarus pulex and and many possible bony fish as a definitive host. They need to reach the definitive host to undergo the final stage of their life cycle in which they are capable of sexual reproduction. Gammarus pulex quite commonly ends up getting eaten by bony fish, and as you can imagine they try to avoid it if they can. They can smell their predators coming and take evasive action. Pomphorhynchus laevis on the other hand wants to get eaten so it can infect its hosts intestines. In order to increase the chance of this they alter the mind of their intermediate host and make them much less responsive to the smell of a predator. This strategy is similar to that of Toxoplasma gondii, which we discussed in an earlier post.
But they don't stop there.  The orange colouration in Pomphorhynchus laevis is visible in its intermediate host while it is infected, and makes them more noticeable to the predators.

Pomphorhynchus laevis are endemic to the Palaerctic region.

Kingdom: Animalia
Phylum: Acanthocephala
Class: Palaeacanthocephala
Order: Echinorhynchida
Family: Pomphorhynchidae
Genus: Pomphorhynchus
Species: Pomphorhynchus laevis

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