Published online 13 December 2007 | Nature | doi:10.1038/news.2007.378

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Worm-eating fungus trapped in amber

Ancient sample catches carnivorous fungus in the act.

Ring around a nematode: this ancient fungi could trap prey with this loop.Science/AAAS

A 100-million-year-old carnivorous fungus has been found encased in amber in southwestern France.

The find is unusual. Ground-dwelling organisms such as this fungus are much less likely to get trapped in sticky tree resin than are insects that alight on tree trunks. And it is the oldest carnivorous fungus ever found; the previous record-breaker is some 15–20-million years old. The new specimen should help to shed some light on the evolution of these strange creatures.

Modern carnivorous fungi capture and kill tiny nematode worms that come to feed on them. Some produce sticky structures that the nematodes get stuck in, others grow small loops that act like a lasso when the nematodes go through. When the nematode dies, the fungus penetrates the worm and digests it.

The evolutionary history of these organisms is difficult to study. They do not have hard parts such as skeletons or shells, so when they die everything rots away. As a result, determining when they first appeared has proven difficult. So the amber-encased sample is an important find.

Worm lasso

Alexander Schmidt at Humboldt University of Berlin in Germany and his colleagues report1 in Science that the encased fungus has loops that are similar to those seen in modern fungi. The loops are just the right size (about 10 micrometres across) to ensnare the nematodes also found in the amber-preserved specimen. One loop contains some detritus, they report, that could be the remains of a nematode that fell into the fungal trap 100 million years ago.

"Fossils showing these interactions are such rare things. This is a once in a lifetime find," says Michael Krings at the Bavarian State Collection for Palaeontology and Geology in Munich. Discovering that the nematode feeding system was around 100 million years ago is "saying quite a lot" says Schmidt.

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Despite the similarities between modern and ancient carnivorous fungi, Schmidt does not think that the find is closely related to any carnivorous species alive today.

The loops of the fossil fungus consist of just one elongated cell each, whereas those on modern carnivorous fungi consist of three cells, notes Schmidt. The structures seem to have the same nematode-trapping function, but are not formed in the same way, as if they evolved independently along different branches of the tree of life. 

  • References

    1. Schmidt, A. R., Dörfelt, H. & Perrichot, P. Science 318, 1743 (2007). | Article |
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