Quirks & Quarks

425-Million-Year Old Parasite Found With Its Host

A worm is captured drilling into a crustacean in an exquisite fossil

Ancient example of parasitism caught in action

The tongue worm parasite (orange) is attached to the host ostracod. (David Siveter)
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A 425-million-year old fossil of a parasite invading its host was recently found in rocks in Herefordshire, England. It is the first parasite of its kind - a tongue worm - to be found invading its host ostracod - a type of crustacean.

Dr. David Siveter, Emeritus Professor of Paleontology at the University of Leicester, studied the fossil and discovered three tongue worms - one inside attached to eggs and two on the outside of the crustacean's shell.

Because the fossil was found in an ancient marine environment, it indicates that the tongue worm made the transition to a land animal parasite at some point. The many species of tongue worm today are parasites of reptiles, snakes and humans.

Related Links

Paper in Current Biology
- University of Leicester release
- Yale University release
- Imperial College London release
- BBC News story
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Dr. Siveter previously on Quirks