The Flea: The Ideal Design for High Jumps

A flea can jump more than 100 times its own body height, which is equivalent to a human jumping 200 meters high. Furthermore, it can continue jumping like this without rest for 78 hours. In general, the flea does not fall onto its legs after the fifth jump, it lands either on its back or head. However, it neither becomes dizzy nor gets injured, which is due to the design of its body.

The skeleton of the insect is not inside its body. It is composed of a hard layer of a compound called sclerotin, which wraps the entire body and is attached to the chitin. Numerous armored plates with limited movement form this outer skeleton, which absorbs and eliminates the shock of jumping.

On the other hand, fleas do not have any blood vessels. The inside of the entire body floats in a clear and fluid blood, which acts as a cushioning around all the internal organs and makes them immune to sudden pressure jumps. The blood is cleaned by means of air vents scattered throughout the body. This eliminates the need for a giant pump to continually pump oxygen. Its heart is shaped like a tube and beats at such a low rate that the jumps do not affect it at all.

Scientists discovered through research that the leg muscles of fleas are not as strong as the jumps would really require. The extraordinary performance enjoyed by fleas is made possible by a kind of spring system that is added to its legs, which works because of a rubberlike protein called "resilin", where the flea stores mechanical energy. The outstanding property of this substance is its ability to release in stretching up to 97% percent of the energy that is stored in it. The most flexible material in the market today has a ratio of 85%. This elastic material is located at the base of the large hind legs of the animal in tiny pads. The flea takes a few tenths of seconds to compress this material as it folds its legs in preparation for a jump. A ratchetlike structure holds the leg folded until a muscle is relaxed and the spring-like structure powers the jump through stored energy in the resilin which translates into tremendous leaps.