Saturday, 11 July 2015

Creature 284: Pristionchus pacificus

Worm which changes personality

Pristionchus pacificus is a roundworm which is sort of half parasitic.

As juveniles they are free living soil dwellers which like nothing more than to munch on soil bacteria. If bacteria are plentiful and there are not too many competitors they will develop a small contracted mouth and continue to feed on bacteria, but of there are not enough bacteria around they develop a wider mouth with teeth equipped for tearing apart and eating other roundworms. This apparent hostility towards competition is nothing like the behavior they exhibit when they grow up.

When they are ready to become adults they will want to to a host. Their hosts are typically dung beetles. In order to maximize their chance of finding a dung beetle host these worms will go to extreme lengths to cooperate. A whole lot of them glue themselves together and form a moving stalk which wriggles around in the hope of making contact with a dung beetle.

But that isn't the end of their general goodwill, these sort of parasites will remain mostly inactive inside the beetle while it is alive. When the beetle dies it will eat the bacteria which grow from feeding off the decaying corpse of the beetle.

This roundworm has a cosmopolitan distribution.

Kingdom: Animalia
Phylum: Nematoda
Class: Chromadorea
Order: Rhabditida
Family: Diplogastridae
Genus: Pristionchus
Species: Pristionchus pacificus

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