Fleas are common bloodsucking parasites. Having no wings, a flea cannot fly, but its flat body slips through the strands of its
host’s hair or fur quite easily on its powerful legs. Only about 3 mm (0.125 in) long, the human flea, Pulex irritans, can jump as
far as 33 cm (13 in). This strength has been harnessed for flea “circuses,” in which fleas perform trained stunts such as pulling
small wagons. Fleas can be quite dangerous, however, because they can carry disease from one host to the next.
