Nov 9, 2011

Mite Fossilized While Sucking on Spider's Head

The world's smallest fossil detected by 3D imaging in amber is a miniscule mite, which 49 million years ago decided to hitch a ride on a spider's head. The unusual pair, described in the latest Royal Society Biology Letters, has been entombed in amber ever since.

The mite measures less than than .2 mm long. Here's a closeup view:

Mites are rare in the fossil record because their small size makes them difficult to study. Using a modern method called phase contrast X-ray computed tomography, Jason Dunlop of Humboldt University Berlin and colleagues successfully scanned the mite and spider in an ancient chunk of Baltic amber. The process enabled them to reconstruct the duo in vivid three-dimensional detail.

Here's the mite's underside:

The mite belongs to a group called the Astigmata, previously almost unknown as fossils.

Dunlop and his team write that members of this group "breed rapidly under ideal circumstances, and in order to facilitate dispersal many of the more basal (i.e. non-parasitic) lineages employ phoresy: attaching themselves to larger arthropod carriers that transport them to hopefully better conditions."

They explain that free-living juveniles handle dispersal in this way.

These young mites "typically adhere to the carrier via a distinct attachment organ or 'sucker plate' composed of various suckers and mechanoreceptors on the underside of the body."

Read more at Discovery News

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