Anteaters belong to the family Myrmecophagidae, which includes four species in three genera. They are found in Trinidad and range from southern Mexico to northern Argentina. The spiny anteater (echidna) of Australia is an egg-laying mammal and is not related to the placental anteaters of the New World. The banded anteater (or numbat) of Australia is a marsupial mammal, and not a close relative of the placental anteaters. The anteater's closest relatives are sloths, armadillos, and pangolins. All belong to the order Edentata, meaning without teeth, although only the anteaters are strictly toothless.
Anteaters feed by shooting their whiplike tongues in and out of insect nests up to 160 times per minute. Ants,
along with sticks and gravel, stick to the sticky tongue like flies to flypaper. Horny papillae toward the rear of the two-foot-long tongue help this toothless mammal to grind its food, which is ground up further by the muscular stomach. It is thought that grit the anteater swallows may actually help its stomach grind up the food. In a typical day, a giant anteater, the largest of four species, will consume up to 30,000 ants.
Anteaters' bodies have a narrow head and torso and a long, slender snout that is kept close to the ground to sniff for insects. Anteaters have poor eyesight and hearing but a keen sense of smell. Their legs end in long, sharp claws that are used primarily to open ant and termite nests but double as defensive weapons. To protect their claws, anteaters walk on their knuckles with their claws turned inward.
A diet of ants and termites provides little energy, so anteaters have adapted by evolving an unusually low resting metabolic rate and low core body temperature, moving slowly, and spending much of the day sleeping. Female anteaters bear only one offspring per year and devote much of their energy to caring for the young.
The largest of the four New World species is the giant anteater (Myrmecophaga tridactyla), which is widely distributed throughout Central and South America east of the Andes to northern Argentina. The giant anteater is about the size of a large dog. It is covered with short, mostly gray hair, except on its tail, which has long, bushy fur. True to its name, the giant anteater subsists almost entirely on large, ground-dwelling ants. It moves between ant nests, taking just a little from each nest, thereby avoiding excessive ant bites and depletion of its food supplies.
Giant anteaters are solitary creatures, pairing up shortly before mating and parting just afterward. Females suckle their young for about six months and carry them on their back for up to a year, when the young anteaters are nearly fully grown. The giant anteater is an endangered species due to habitat destruction and hunting.
The lesser, or collared, anteater consists of two species, Tamandua mexicana and T. tetradactyla. Tamandua mexicana is found from southern Mexico to northwestern Venezuela and Peru, while T. tetradactyla lives in Trinidad and South America, east of the Andes, from Venezuela to northern Argentina and southern Brazil. Lesser anteaters are distinguished from giant anteaters by their large ears, prehensile tail, and affinity for climbing trees. They are about half the size of giant anteaters and are covered with bristly hair that varies in color from blond to brown. The term collared anteater refers to the band of black fur encircling the abdomen, found in T. mexicana and T. tetradactyla from the southeastern part of their range. The tree-climbing lesser anteaters feed mostly on termites. Like the giant anteater, the female tamandua carries her offspring on her back.
The most elusive of the four species of anteater is the silky anteater (Cyclopes didactylus). This squirrel-sized animal spends most of the day sleeping in trees, and comes out to forage for ants at night. Silky anteaters are distributed from southern Mexico to most of the Amazon basin, and west of the Andes to northern Peru. These anteaters rest on branches of the silk cotton trees, where its silky, gold and gray fur blends with the tree's soft, silver fibers. This camouflage protects the silky anteater from owls, eagles, and other predators. In this species, both parents feed the young, and both carry their offspring on their backs.
Gould, Edwin, and Gregory McKay, eds. The Encyclopedia of Mammals. 2nd ed. New York: Academic Press, 1998.
Nowak, Ronald M. Walker's Mammals of the World. Baltimore: The Johns Hopkins University Press, 1999.
"Quick-snacking Anteater Avoids Attack" Science (8 August 1991): 88.