Only a true insect lover will appreciate the remarkable traits of fleas. Fleas entertained people in the 19th century, when flea circuses were popular sideshow attractions. Today, they're considered a pest to pet owners, and a persistent one at that. Siphonaptera, which is Greek in origin, means tube (siphon) without wings (aptera).
Description:
All adult fleas suck blood from host animals, usually mammals. These ectoparasites are well-equipped for life on a furry food source. A hungry flea in search of a bloodmeal uses its maxillary blades to puncture the skin of its host. A bit of flea spit keeps the blood from clotting while the parasite assembles its siphon, using modified mouthparts which form a tube.
Flea bodies are flattened laterally, giving them a thin profile for moving between hairs. Tiny bristles project backwards from the head so they don't get tangled when the flea moves forward. These projections, called ctenidae, help the flea hang on to Fido when he starts scratching. Fleas lack compound eyes, but may have two small ocelli.
Siphonapterans undergo complete metamorphosis. The female flea lays up to two dozen eggs per day. Eggs fall from the host animal, and hatch into larvae within a few days. Larvae have no legs, and feed on whatever waste falls their way, usually excrement from adult fleas. Within weeks, the larvae spin their silken cocoons, and pupate. Adult fleas emerge in weeks or months, depending on species and temperature.
Though descended from flying insects, fleas have evolved into wingless arthropods. Their only need for locomotion is to land on a host, and for that they've developed superior jumping abilities. Fleas can launch themselves quite high in the air, up to 80 times their own height. In addition to strong rear legs designed for jumping, fleas have a substance called resilin above the hind legs. This rubbery substance compresses as the flea prepares to jump, storing potential energy. When the flea thrusts upward, this energy is converted to kinetic energy, the energy of motion.
Habitat and Distribution:
Fleas live wherever you find mammals, throughout the world. Most of the nearly 2,400 described species of fleas live in temperate zones.
Major Families in the Order:
- Pulicidae – common fleas
- Ceratophyllidae – bird and rodent fleas
- Ischnopsyllidae – bat fleas
- Rhopalopsyllidae – marsupial fleas
Families and Genera of Interest:
- Cat fleas, Ctenocephalides felis, are the most common fleas found on dogs (and cats, of course).
- Rodent fleas are best known as vectors of the Black Death, aka Bubonic Plague, which wiped out much of the world's population during the Middle Ages.
- Female sand fleas (Tunga penetrans) take up residence under people's toenails.
Sources:
- Insects - Their Natural History and Diversity by Stephen A. Marshall
- Siphonaptera.(Accessed April 30, 2008).
- Gordon's Flea Page (Accessed April 30, 2008).
