If you have ever watched a flea jump, you may be startled to see that they can jump astonishingly high (and far) compared to their size. This is down to a combination of strong leg muscles and pads of a rubber-like protein called resilin which is located above the hind legs of the flea.
When the flea prepares to jump, it crouches which squeezes the resilin. This resilin is able to store energy and release it suddenly in one go, a bit like a spring. This launches the flea as it from a catapult allowing the flea to jump up to around 35 centimetres in length and 20 centimetres in height.