Anteaters

(Myrmecophagidae)

Class Mammalia

Order Xenarthra

Family Myrmecophagidae

Thumbnail description
Small to large functional insectivores, characterized by a very elongated tapered and tubular snout, teeth are absent, wormlike tongue that is capable of extending beyond head length, large powerful curved claws, all but one species has grasping prehensile tail

Size
12–110 in (0.32–2.8 m); 0.5–86 lb (0.15–39 kg)

Number of genera, species
3 genera; 4 species

Habitat
Neotropical forests, savannas, and grasslands

Conservation status
Vulnerable: 1 species

Distribution
Belize, Mexico, Central and South America

Evolution and systematics

Fossil evidence indicates that the family Myrmecophagidae was present during the early Miocene period (25 million years ago [mya]) in South America. However, the fossil record is poor and it is possible that the family is much older. Myrmecophagidae is the only member of the infraorder Vermilingua, which means worm-tongue. There are three genera and four species. Anteaters were once thought to be closely related to sloths. However, analysis of albumin samples indicates that the members of the order Xenarthra diverged about 75–80 mya and are very distinct.

Physical characteristics

All members of this group have elongated snouts and a thin tongue that is capable of extending outward to a length greater than the length of the head. They have a tubular mouth with lips but they do not have teeth. They also have large curved foreclaws that are used to tear open ant and termite mounds. The powerful foreclaws can also be used as lethal weapons for defense. All but one species has a grasping prehensile tail. The

fur is long and thick to protect them briefly from the attack of ants as well as termites.

Distribution

Two members of this group are found as far northward as Southeastern Mexico, the other two members begin their northernmost range in Cental America. The ranges of three members of this group overlap to eastern Brazil. Two species extend southward to Uruguay.

Habitat

Anteaters can be found in tropical dry forests, rainforests, grasslands and savannas. The silky anteater (Cyclopes didactylus) is an arboreal specialist that is most commonly found in rainforest. The tamandua are arboreal and terrestrial opportunists in regards to terrain and food resources. They are most commonly found in dry forests near streams and lakes. The giant anteater (Myrmecophaga tridactyla) is almost entirely terrestrial and usually found in grasslands and savannas.

Behavior

Anteaters are thought to be mostly solitary. The limited number of field studies done indicate that all members of this group will defend their 1–1.5 mi² (2.6–3.9 km²) territories. Males often enter the territories of associated females but do not enter the territories of other males. Likewise, females do not enter the territories of other females. If a territorial dispute occurs, they will vocalize, swat with the foreclaws and sometimes sit on and even ride the back of a subordinate animal.

Observations indicate that anteaters have a poor sense of sight, being able to see better the closer they get to the subject. However, their sense of smell is exceptional. Most species depend on smell for direction, foraging, feeding and defense. They are thought to be able to hear very well.

Anteaters are unique in the fact that they have the lowest body temperature of any mammal. Their normal body temperature is also more variable and they can safely tolerate more fluctuation in body temperature than most mammals. The body temperature of a giant anteater fluctuates between 90 and 95°F (33–36°C). There is evidence from field studies that anteaters operate at the minimal energetic requirements for a mammal feeding on insects. In other words, energy consumed from food is only slightly greater than the energy used in everyday activities. It is suspected that anteaters coordinate their body temperatures with respect to activity and energy requirements. They can conserve energy with a lower body temperature during periods of rest; conversely when increased activity levels are needed during periods of foraging or hunting for example, the body temperature increases as a result of this energy requirement.

Feeding ecology and diet

Anteaters are specialized to feed on formidable insects. Very few mammals would consider feeding on invertebrates that are capable of defending themselves with powerful jaws, a potent sting, prickly armor, and in some species the ability to shoot acids and toxins at the enemy. The feeding strategy of anteaters is to lick up as many ants and termites as possible, as quickly as possible. The insect attack quickly becomes unbearable. In fact, an anteater spends only about a

minute at a typical nest before it must move on to another. These animals must feed on thousands of ants and termites each day to satisfy their caloric requirements. For example, a giant anteater may visit close to 200 ant and termite nests a day in order to get enough food. Anteaters feed on many different species of ants and termites, both terrestrial and arboreal;

however, the bulk of their diet is composed of only a few species. Each anteater species has specific insect preferences, depending on the locality in which it is found. Anteaters also practice resource partitioning. The species of insects upon which they feed depends on ant and termite nest construction and the location of that nest. Some ant and termite species are arboreal and only found on small branches, making them inaccessible to large anteater species. Others have a hard covering on the nest making it impenetrable to smaller anteater species.

An anteater's tongue is darted in and out very quickly and is covered with thousands of tiny hooks known as filiform papillae. These hooks help to grasp insects. Large quantities of saliva also help to hold the insects until they reach the mouth. Slight side to side movements of the jaws aid in moving the tongue and swallowing. The stomach of an anteater is specialized to aid in digestion much like the gizzard of a bird. The stomach has hardened folds and uses strong contractions as well as small bits of ingested sand and dirt to grind the insects.

Reproductive biology

Visual sex determination of anteaters is sometimes possible. Adult males tend to be slightly larger overall and have a wider

head and neck as well as a more muscular build. The penis and testes are located internally in the abdominal cavity between the rectum and urinary bladder. As a result, the only sure way to determine the sex of an anteater visually is to observe the shape and size differences of the urogenital opening. In males, the opening is more ventral and greatly reduced. Thus, the distance from the anus to the urogenital opening is greater in males. Females have a shorter ano-genital distance, the uro-genital opening is long and has a mound-like shape. This can sometimes be seen at a distance with the larger species when the tail is raised, otherwise the animal must be captured for close identification. There is no intromission during breeding, fertilization occurs as a result of contact transfer similar to that observed in some species of lizards. Usually only a single offspring is produced from polygynous mating, twins are possible but very rare. Females have a single pair of mammae near the armpits from which the offspring nurse. Mothers are unable to grasp the newborn offspring due to the enlarged foreclaws; therefore, newborn youngsters must climb up the long extended fur to the mammae. In most species, the young are transported on the mothers back until they are self-sufficient.

Conservation status

Accurate census numbers on these animals have been difficult to obtain. They are solitary, have a low reproductive rate, are difficult to find, and seem to have large home ranges; these factors make population studies very challenging. As a result, their natural history is poorly understood and their conservation status is difficult to assess. They are found in a wide range of habitats. However, much of their range is suffering from the pressures of habitat alteration, destruction and human encroachment. It has yet to be determined how well they can adjust and survive in disturbed habitat. Their survival is also linked to the availability and health of ant and termite populations. This group is in desperate need of detailed study.

Significance to humans

Members of this group are hunted for sport and for their skin. Rope is made from the tendons of the tail from the species that have prehensile tails. They are often kept as pets and used by native peoples in their homes for ant and termite control.

Species accounts

List of Species

Silky anteater

Cyclopes didactylus

taxonomy

Cyclopes didactylus (Linnaeus, 1758), Suriname.

other common names

English: Pygmy, golden or two-toed anteater; French: Flor de balsa; German: serafin; Spanish: Angelito, tapacara, gato balsa.

physical characteristics

Total length 12–21 in (32–52 cm); weight 6–13 oz (175–357 g); tail length 6–12 in (16–30 cm). Small arboreal mammal with long, wavy, soft and silky fur. Silvery gray to golden yellow in color with a brown mid-dorsal stripe. Small tubular mouth with a pink nose. Tail is highly prehensile. There are two toes on each forefoot, each with large curved and sharp claws. Four toes on each hindfoot, each with small claws. The hindfoot is highly modified to grasp small branches.

distribution

Mexico, Central America, Brazil, Peru and Bolivia.

habitat

Lives among the trees and lianas of moist tropical forests, rarely descending to the ground. The silky anteater shows a preference for the crown of the silk-cotton tree of the genus Ceiba, it is concealed very well among the golden fibrous seed pods produced by this tree.

behavior

Nocturnal, slow-moving and inoffensive; however, it will defend itself with quick, forceful slashes of the powerful claws. Silky anteaters rarely spend more than one day in the same tree. Their principal predators are harpy eagles (Harpia harpyja), eagle-hawks, and spectacled owls (Pulsatrix perspicillata).

feeding ecology and diet

Forages about the canopies of trees in search of arboreal insects, predominantly ants. Its small size and specialized hind foot allow the silky anteater to use higher and smaller branches and associated ant colonies that larger insectivores cannot physically access. Adults typically consume about 5,000 ants per day.

reproductive biology

Usually a single young is born after a gestation period of 120–150 days. Depressions or holes in trees that are partially filled with dry leaves are often used as nests. May be polygynous.

conservation status

Not threatened. However, this is a very secretive and solitary species, which makes a census very difficult. Also, this species has a poor husbandry record in captivity, seldom surviving for more than 30 days. The longevity record for this species in captivity is two years and four months. At the time of this writing this species was not represented in captivity.

significance to humans

Occasionally hunted for food.

Southern tamandua

Tamandua tetradactyla

taxonomy

Tamandua tetradactyla (Linnaeus, 1758), Pernambuco, Brazil.

other common names

English: Collared anteater, lesser anteater; French: Tamanduacolete; German: Termieteneter; Spanish: Oso colmenero.

physical characteristics

Total length 37–58 in (93–147 cm); weight 7–16 lb (3–7 kg); tail length 16–26 in (40–67 cm). Pale golden yellow with a black "vest" over the shoulders, chest, belly and lower back. The vest is highly variable and may cover the entire body or be totally absent. Prehensile tail, head long and curved downward, long coarse hair. Forefeet with four long, powerful curved claws. Hindfeet with five smaller claws. Tamanduas walk on the outside of the hand with the claws turned inward.

distribution

East of the Andes from Venezuela to Argentina and Uruguay.

habitat

Savanna, thorn scrub and dry forests, rainforest.

behavior

Nocturnal, crepuscular, or diurnal. Tamanduas are opportunistically terrestrial and arboreal depending on terrain and available resources. When threatened it may hiss and release a fowl odor from the anal gland. As a last resort they will defend themselves with the powerful foreclaws and often grab and hold the opponent, keeping it away from the body. Tamanduas seek shelter in hollow trees or holes in the ground.

feeding ecology and diet

Opportunist feeding on terrestrial as well as arboreal ants and termites. It can open arboreal nests too tough for silky anteaters. They occasionally feed on bees and honey.

reproductive biology

May be polygynous. Mating takes place in the fall, usually a single young is born in the spring after a gestation period of 130–150 days. The offspring is carried on the back of the mother for about a year, gradually becoming self sufficient. Tamanduas commonly reproduce in captivity and have survived for more than 9 years.

conservation status

Not threatened.

significance to humans

Sometimes used by Amazonian Indians to rid their homes of ants and termites.

Northern tamandua

Tamandua mexicana

taxonomy

Tamandua mexicana (Saussure, 1860), Mexico.

other common names

English: Collared anteater, lesser anteater; French: Tamanduacolete; German: Termieteneter; Spanish: Oso hormiguero comun, brazo fuerte.

physical characteristics

Total length 40–51 in (102–130 cm); weight 7–12 lb (3–5 kg); tail length 16–26 in (40–67 cm). Coarse, dense fur is colored fawn to brownish with a black "vest" down its back. Tongue can extend 1.3 ft. (0.4m). Tail is prehensite; fore feet have four claws, and hind feet have five claws.

distribution

Southeast Mexico, Central America, South America west of the Andes from northwestern Venezuela to northwestern Peru.

habitat

Savanna, thorn scrub and dry forests, rainforest.

behavior

Diurnal and nocturnal, arboreal and terrestrial. Tamanduas are often accompanied by thick clouds of flies and mosquitoes in the rainforest. A population density of 0.05 animals per 2.5 acres (1 ha) and a home range size of 61.8 acres (25 ha) has been recorded on Barro Colorado Island, Panama.

feeding ecology and diet

Feeds on terrestrial as well as arboreal ants and termites. Montgomery (1985) reports about 9,000 ants per day consumed by animals on Barro Colorado Island.

reproductive biology

A single young is born in spring after a gestation of 130–150 days. Probably polygynous.

conservation status

Not threatened at this time, however, habitat destruction is a threat to this species in much of the range. At the time of this writing this species had only one known representative in captivity.

significance to humans

The tendons of the tail are used to make rope.

Giant anteater

Myrmecophaga tridactyla

taxonomy

Myrmecophaga tridactyla Linnaeus, 1758, Pernambuco, Brazil.

other common names

English: Ant bear; French: Tamandua bandeira; Spanish: Oso caballo.

physical characteristics

Total length 68–110 in (174–280 cm); weight 48–88 lb (22–39 kg); tail length 25–35 in (64–90 cm). Long, thick, coarse and stiff fur colored with black, brown, white and gray bands. Forelegs are white, wrists are crossed by a black band. The head is greatly elongated and narrow. The eyes are small and the ears are rounded. The worm-like tongue can extend more than 2 ft (0.6 m) outward. The tail is long, bushy and it is not prehensile. Forefeet with four sickle-shaped claws, the center two being greatly enlarged and powerful, the hindfeet have five short claws.

distribution

Guatemala, Panama, South America, east of the Andes to Northern Uruguay and west of the Andes to Northern Argentina.

habitat

Dry forest, rainforest, savanna, and grasslands. Primarily terrestrial but capable of climbing. Can also swim across large bodies of water.

behavior

Nocturnal and diurnal. A large terrestrial animal known to cover an average of 7 miles (11 km) a day while foraging in its home range of 22,240 acres (9,000 ha). Giant anteaters walk on their knuckles due to the extreme size of the foreclaws. They can be functionally bipedal while searching, digging, feeding and during times of defense. Depressions in the ground are used as shelter and the animal covers itself with the tail. Adults make a roaring sound when disturbed. Giant anteaters are capable of flicking their tongue at speeds of 160 times per minute. In captivity, they have been known to live for over thirty years.

feeding ecology and diet

Feed primarily on ants and termites. Occasionally feed on beetle larva, soft fruits and carrion. Giant anteaters often consume more than 30,000 insects per day.

reproductive biology

Probably polygynous. Sexual maturity has been achieved at 18 months of age in captivity. Females give birth to a single young after about 190 days gestation. The young are patterned identically to the mother; while being carried on the mother's back the bands of the two animals visually unite and provide camouflage. The young nurse for approximately two months, then begin taking insects. Neonates often ride on the mothers back for six to nine months before they become self-sufficient. They grasp the long hairs of their mother and produce a shrill call if isolated.

conservation status

Vulnerable; threatened in much of the range due to habitat loss and hunting. There are also many losses due to wild fires, as the fur is quick to ignite from stray sparks.

significance to humans

Hunted for trophies, food and skin.

Resources

Books

Emmons, Louise H. Neotropical Rainforest Mammals, A Field Guide. Chicago: University of Chicago Press, 1990.

Engelmann, G. F. "The Phylogeny of the Xenarthra." In The Evolution and Ecology of Armadillos, Sloths, and Vermilinguas, edited by G. Gene Montgomery. Washington, DC: Smithsonian Institution Press, 1985.

Flint, Mike. North American Regional Studbook for the Giant Anteater. Tucson: Reid Park Zoo, 2001.

Montgomery, G. G. "Cyclopes didactylus." In Costa Rican Natural History, edited by D. H. Janzen. Chicago: University of Chicago Press, 1983.

Montgomery, G. G. "Impact of Vermilinguas On Arboreal Ant Populations." In The Evolution and Ecology of Armadillos, Sloths, and Vermilinguas, edited by G. Gene Montgomery. Washington, DC: Smithsonian Institution Press, 1985.

Periodicals

Best, R. C., and Y. Harada. "Food Habits of the Silky Anteater (Cyclopes didactylus) in the Central Amazon." Journal of Mammalogy 66 (1985): 780–781.

Ken B. Naugher, BS