Flukes: Trematoda

Physical characteristics: Adult lancet flukes have pearly bodies shaped like long, thin leaves. The suckers are on the mouth and on the bottom of the worm toward the front of the body. The mouth sucker closest to the front is a bit smaller than the other suckers. Lancet flukes are about three-sixteenths to five-eighths of an inch (5 to 15 millimeters) long and one–thirty-second to a little more than one-sixteenth of an inch (2 millimeters) wide.

Geographic range: Lancet flukes live in the northeastern United States, Australia, northern and central Europe, Asia, and Africa.

Habitat: Lancet flukes live in dry habitats. The primary hosts are mammals such as sheep, cattle, pigs, rabbits, deer, and woodchucks. The first intermediate hosts are land-dwelling snails, and the second intermediate hosts are ants.

Diet: Lancet flukes feed on the cells of their hosts.

Lancet flukes cause liver disease in farm animals. (Photo Researchers. Reproduced by permission.)

Behavior and reproduction: Lancet flukes begin life as eggs in the feces of their primary hosts. The eggs are picked up and carried by snails. The larvae form slime balls in the snail, which ejects them through its breathing pore. The larvae are picked up by ants and cause cramping in the ants' jaws. The cramping causes the ants to clamp down on blades of grass and become stuck. The larvae then are eaten by grazing animals, such as sheep and cattle, and develop to the adult stage in the animal's liver. The eggs leave the host in its feces, and the cycle starts over. Adult lancet flukes make both eggs and sperm and either mate with other flukes or fertilize themselves.

Lancet flukes and people: Lancet flukes cause liver disease in farm animals.

Conservation status: Lancet flukes are not threatened or endangered. ∎