from the book, "Petrified Lightning"
All owners of furry or feathered pets will at some time live with fleas on the premises. These tiny insects feed on the blood of birds and mammals, including any humans that might be around. Unless the animal is badly infested, fleas aren't easy to see. They avoid the sparse—hair regions and head for home in the forest of thick hair.
Occasionally a flea will fall or jump off a pet and be stranded on the carpet. Since flea food—fresh blood supplied by the host animal—is not plentiful on a carpet, a human that walks in the room is a welcome source of food for the wandering flea. The new host often isn't aware of having been selected as a flea meal and will go to bed that night not knowing of a new tenant residing somewhere around the ankles. In the morning numerous itching welts give evidence of the presence of a flea. By this time the flea is usually back home in the forest of hair of its favorite pet, much pleased to be enjoying its usual host.
Fleas, natural—born jumpers, confine their leaps to hopping from place to place on the host. They are built conveniently narrow so that they can walk through coarse hair. Jumping ability is a safety valve in case they need to move from here to there rapidly. Nevertheless, for an insect less than one—eighth inch (3 mm) long, the flea's ability to make a long jump of 13 inches (33 cm) and a high jump of 8 inches (20 cm) is quite spectacular.
The jumping power of the flea comes both from strong leg muscles and from pads of a rubberlike protein called resilin located above the flea's hind legs. To jump, the flea will crouch, thereby squeezing the resilin, and then relax certain muscles. Stored—up energy from the resilin works like a gigantic spring that launches the flea. Perhaps launching is too mild a word to describe the action of a species that can jump 150 times its own length horizontally or 80 times vertically.
To reach the same distance as the flea, proportionately, a human being would have to spring horizontally the length of two and a half football fields or vertically the height of a 60—story building—in a single bound, from a stationary sprint position. The best Olympic long jumper, at 29 feet (about 10 yards), would have to add 240 yards to the previous score. An Olympic jumper might appeal for help by pleading, "Oh, to be a lowly flea!" Otherwise the Olympic gold might go to the lowly flea.