> 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 areexternal parasites to mammals and birds. They lack wings, but have hind legs forjumping. Their legs enable them to leap a distance of 50 times their bodylength.For something so tiny, fleas have played an instrumental role in modernsociety’s genetic makeup. Many centuries ago, infected fleas were responsiblefor the instigation and spread of the bubonic plague. In fact, they continue tobe vectors for disease even today: all it takes is one infected flea bite tocreate an immune system response in humans. Luckily, while advances in modernmedicine prevent any real outbreak of once-cataclysmic diseases such as theBlack Death (as the bubonic plague epidemic was once called), fleas continue tojump powerfully from one host to the next carrying their bounty of blood.One of the most impressive features of these tiny parasites is their evolvedability 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 thejumping mechanism. For example, on flying insects, a rubbery protein known as resilin [https://www.britannica.com/science/resilin] forms a hinge where thewings attach to the body. Resilin absorbs tension created during each wingstroke, and the stored energy is transferred into the initiation of thefollowing stroke. Fleas, despite their wingless state, have a similar hinge andrelease in their tiny but powerful legs.Check out a flea in motion (and in startling 4k) below.