A Gordian worm grows up inside an insect, then leads its host to drown itself so the worm can free itself. But, should an aquatic predator get to the insect first, the worm has an escape plan, says an international research team.
This marks the first time scientists have documented this escaping-parasite trick, says Fleur Ponton of the Institute of Research for Development in Montpellier, France.
Typical hosts such as crickets aren’t aquatic, but the worms make them so erratic that they hop into water. The crickets eventually drown, but the parasite escapes into the water, its natural adult environment, to breed.
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Once the cricket hits the water, the worm needs about 10 minutes to wriggle free. During this interlude, the cricket makes an attractive target for frogs, fish, and other predators. If something eats the cricket, the worm just keeps on wriggling until it emerges through the predator’s mouth or gills (Click here to see video), Ponton and her colleagues report their findings in the April 6 Nature.
The researchers recorded more than 20 worm escapes from trout, 6 from perch, and 6 from frogs.