Living on the hope

Fleas are small wingless insects that live by sucking blood. They are best known for their amazing jumping ability. A flea can jump 18 cm high and 33 cm long. This is amazing considering that fleas are only 1.5 - 3,3 mm long.

Appearance and characteristics

The jump is so explosive that the muscles could never achieve it themselves. The flea therefore stores muscle energy in an elastic pad that it clamps together by bending the hind leg. A special mechanism then locks the joint. When the flea wants to jump, the locking mechanism releases whereby the cushion springs back and the leg is extended with violent force and shoots the flea away.

Fleas are flattened from the sides which facilitates their crawling between hairs or feathers on their host animals. Most fleas only suck blood from a particular species of bird or mammal or from one animal group eg. bats. Others are less particular. The flea holds on to the host animal with its strong claws and with the stiff backward bristles they have on the abdomen while it sticks its sharp proboscis through the host's skin and sucks blood. Unlike most other insects, fleas do not have facet eyes but only simple eye spots. Some species lack eyes completely.

The body of the flea is covered by hard plates, sclerites, with backward hair and thorns. These protect the flea from the host animal's scratching as it tries to get rid of its itchy tormentor.

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