The Mighty Flea

Which living creature can jump a distance of 50 times its body length?

And the answer: the flea.

Photo courtesy: public domain. 

Those annoying tiny insects known as fleas are external parasites to mammals and birds. They lack wings, but have hind legs for jumping. Their legs enable them to leap a distance of 50 times their body length.

For something so tiny, fleas have played an instrumental role in modern society’s genetic makeup. Many centuries ago, infected fleas were responsible for the instigation and spread of the bubonic plague. In fact, they continue to be vectors for disease even today: all it takes is one infected flea bite to create an immune system response in humans. Luckily, while advances in modern medicine prevent any real outbreak of once-cataclysmic diseases such as the Black Death (as the bubonic plague epidemic was once called), fleas continue to jump powerfully from one host to the next carrying their bounty of blood.

One of the most impressive features of these tiny parasites is their evolved ability to grip and jump with intense accuracy and range. During evolution, fleas – like the majority of parasitic insects – lost their wings. However, certain parts of the flight mechanism have since been incorporated in the jumping mechanism. For example, on flying insects, a rubbery protein known as resilin forms a hinge where the wings attach to the body. Resilin absorbs tension created during each wing stroke, and the stored energy is transferred into the initiation of the following stroke. Fleas, despite their wingless state, have a similar hinge and release in their tiny but powerful legs.

Check out a flea in motion (and in startling 4k) below.

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