First Fleas

Parasites are pretty cool—whether zombifying viruses or prehistoric lice—as long as you’re not the victim/host, you have to respect their ways.

That’s why we were thrilled about last week’s publication of the earliest evidence of fleas in the journal Nature.

Fossilized fleas were found in rocks in China and could date back as far as 165 million years ago. Like other life at the time, these suckers were huge—up to 10 times the size of today’s fleas. The females measured up to 20 millimeters, the males up to 15mm. Yikes!

As judged by their mouthparts—sharp, long siphons—their hosts were bigger, too. Researchers speculate that feathered dinosaurs were at the receiving end. (Try to imagine those beasts scratching an itch…)

Like their modern relatives, the ancient fleas were wingless, but unlike today’s fleas, the fossilized insects lacked leaping abilities—their hind legs were too short. The study’s co-author, Michael Engel, offers a possible explanation for this in Nature News:

they may indicate that the fleas were ambush specialists, which caught meals by “hiding in the periphery and then scrambling onto the host for brief periods to feed before bolting again.”

These possibly may be the first fleas. Ed Yong reports in Discover why they may not have appeared any earlier than the Jurassic period:

[Co-author André] Nels thinks that fleas emerged much later because they couldn’t hang on to the naked skin of Triassic vertebrates. Only in the Jurassic, when animals started to evolve feathers and fur, could the early fleas anchor themselves while they sucked.

Image: D. Huang et al, Nature