TENRECS: Tenrecidae

PHYSICAL CHARACTERISTICS

Rat- or shrew-like in general appearance, tenrecs vary greatly in body size, tail length, and color. One of the most consistent features is the long, pointy snout that is typically adorned with long whiskers. The smallest tenrecs have head and body lengths of just 2 inches (5.5 centimeters) and weights of 0.14 ounces (4 grams), while the largest can reach 14 inches (35.7 centimeters) and weigh up to 44 pounds (2 kilograms). Tails vary from tiny, unnoticeable stubs to long and very obvious structures stretching up to three times the length of the body. Some species have soft yellow to brown fur, and a few have vivid black-and-white or yellow-and-black fur patterns. Adults in several species have sharp spines that are quite effective in thwarting attacks by would-be predators. Some youngsters, like the common tenrec, have blunt spines that produce a sound when rubbed together.

GEOGRAPHIC RANGE

Tenrecs live in Madagascar and western central Africa. Introduced to Comoros, Mascarenes, and Seychelles, which are islands in the Indian Ocean.

HABITAT

Most species live in humid forests or in grasslands. A few species can survive well in marshy areas, drier forests, or agricultural fields. Aquatic tenrecs and otter shrews spend much of their time in or near freshwater streams.

DIET

The tenrec diet varies considerably among species. For the most part, the land-living tenrecs eat insects, worms, and other invertebrates (animals without backbones). A few will also devour baby mice and other small vertebrates (animals with backbones), and some will even munch on dead animals they come across. The tenrecs that live in marshes, near streams, or in the water dine on other water-loving creatures, like aquatic insects, frogs, fishes, mollusks, and crabs.

BEHAVIOR AND REPRODUCTION

Scientists have few details about many species of tenrecs, partly because the animals are relatively small and are typically only active at night. They rest during the daytime, often in tunnels that they construct. Some, like the Ruwenzori otter shrew, sleep on beds of grass in the tunnels. During their daily rest, several species are known to enter a state of deep sleep, called torpor, which allows them to conserve their energy. One species, known as the large-eared tenrec, is particularly tuned in to the outdoor temperature, and its internal body temperature quite closely matches the outdoor temperature. When weather becomes cool, its body temperature takes a similar dip, and the animal may enter torpor. In long, dry periods, some species take an extended deep sleep, called estivation (est-ih-VAY-shun), during which the heart rate and body temperature fall and the animal needs to burn far less energy to stay alive. Estivation may last days or even weeks. Tenrecs that estivate for longer periods will frequently plug the openings of their burrows in preparation for the extended sleep.

TOGETHERNESS AMONG TENRECS

Usually, less than a handful of different mammals from the same group live together within a small area. With tenrecs, it is different. In one small, forested area in Madagascar, sixteen different species of tenrecs share the same space. This type of high diversity among one type of animal is extremely rare, and may, in fact, represent the greatest concentration of such similar animals found anywhere in the world.

Adults likely spend most of their lives alone, coming together only for mating. Sometime, males will remain with the female while she's pregnant, a span that typically lasts about two months. A few reports suggest that some male-female pairs may remain together during other times of the year, too. Overall, scientists know little about mating rituals in most species, but they have observed some behaviors. In the hedgehog tenrec, for example, the females give off an odor during mating season that causes a milky substance to flow from glands near the eyes of males. Each year, females have one litter of one to thirty-two babies, depending on the species. The young, most of which are born blind and naked, apparently stay with the mother for at least four or five weeks, and possibly more.

TENRECS AND PEOPLE

Of all the tenrecs, the most popular is perhaps the greater hedgehog tenrec, which has become quite a popular pet. In Madagascar, which has a thriving tenrec community, humans have traditionally viewed the animals as a source of prime meat, and enthusiastically hunted them. Humans also hunt the giant otter shrew for its pelt.

CONSERVATION STATUS

Ten species are at risk, according to the Red List of the World Conservation Union (IUCN). One, the tree shrew tenrec, is listed as Critically Endangered, facing an extremely high risk of extinction, or dying out; six are Endangered, facing a very high risk of extinction; and three are listed as Vulnerable, facing a high risk of extinction. Many of these species exist in small areas and are threatened by human activities that are changing their habitat. For example, the aquatic tenrec is an Endangered species that is found in only a few spots in Madagascar. It needs clean rivers to survive, but agriculture and deforestation are either eliminating the rivers or allowing silt to muddy up the waters.

COMMON TENREC (Tenrec ecaudatus): SPECIES ACCOUNTS

Physical characteristics: A grayish brown to reddish brown animal with long, coarse hairs and a lighter-colored belly. It has small, beady eyes, small ears, a long and pointed snout with lengthy whiskers, a short and unnoticeable tail, and front legs that are a bit longer than the hind legs. Youngsters have streaked fur and two rows of blunt spines down their backs, but the stripes disappear when they get older, and the spines are covered with longer fur. Adults weigh about 42 to 70 ounces (1.2 to 2 kilograms), and are about 10.5 to 15.3 inches (26 to 39 centimeters) from nose to rump.

Geographic range: Common tenrecs live in Madagascar. Introduced populations also live on the islands of Comoros, Mascarenes, and Seychelles in the Indian Ocean.

Habitat: Common tenrecs usually live in forested areas with a nearby water source such as a river or paddy field.

Diet: Insects, earthworms, and other invertebrates are their primary food, but they will also eat small vertebrate animals, fruit, and plant roots on occasion.

Behavior and reproduction: Adults live alone for most of the year, spending days sleeping in the burrows they make, and nights on the prowl for food. In the dry winter months, food can become quite scarce, triggering the tenrecs to enter a state of deep sleep, called estivation, for up to several months. They mate in the spring, and females give birth to a single litter of twelve to thirty-two babies in the summer, which falls in December and January for these creatures of the Southern Hemisphere. The mother nurses her young for almost a month, then takes them out with her to search for insects and other food items. By the time they are two to two-and-a-half-months old, the youngsters leave the mother to live on their own.

Common tenrecs and people: Humans in Madagascar hunt this species for meat, which is considered a delicacy.

Conservation status: The common tenrec is not considered to be threatened. ∎

YELLOW-STREAKED TENREC (Hemicentetes semispinosus): SPECIES ACCOUNTS

Physical characteristics: A small, black tenrec with a mane of longer golden-yellow to whitish hairs as well as yellow to whitish stripes down the center and on either side of its face. It has a lighter-colored belly, and its back sports scattered, long, yellowish spines. This species has small eyes, black ears, and a long, pink snout, but no noticeable tail. The yellow-streaked tenrec is about 6 to 7.5 inches (15 to 19 centimeters) long, and weighs 3 to 7 ounces (90 to 220 grams).

Habitat: This is a burrowing species that lives in humid forests, as well as shrubby areas, frequently near a water source.

Diet: The yellow-streaked tenrec prefers earthworms but will also eat other invertebrates.

Behavior and reproduction: Unlike most other tenrecs, which are loners much of the year, yellow-streaked tenrecs can either live alone or share their burrows with up to two dozen members of their families, including parents, grandparents, cousins, and siblings. Females may have more than one litter per year, usually with five to eight babies at a time. The babies quickly mature, becoming old enough to mate at just five weeks old.

Yellow-streaked tenrecs survive the dry winter months by estivating in their burrows.

This tenrec's spines come in two types: barbed and stridulating (STRIH-juh-late-ing). A barbed spine is sharp with tiny barbs, or hooklike structures, at the end. These spines detach easily from the animal. When a predator is foolish enough to nip at this tenrec, it gets a mouthful of spines that fall off the tenrec and stick in the predator. Stridulating spines aren't barbed, and don't fall off the tenrec's body so easily, but they do have their own unusual characteristic: they produce a sound when rubbed against one another.

Yellow-streaked tenrecs and people: This species has little contact with humans. Humans do not consider them pets, pests, or a source of meat.

Conservation status: The yellow-streaked tenrec is not considered to be threatened. ∎

FOR MORE INFORMATION

Books:

Garbutt, N. Mammals of Madagascar. New Haven, CT: Yale University Press, 1999.

Goodman, S. M., and J. P. Benstead, eds. The Natural History of Madagascar. Chicago: The University of Chicago Press, 2003.

Periodicals:

Eisenberg, J. F., and E. Gould. "The Tenrecs: A Study in Mammalian Behavior and Evolution." Smithsonian Contributions to Zoology 27 (1970): 78–89.

Web sites:

Gorog, A. "Tenrec ecaudatus." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Tenrec_ecaudatus.html (accessed on July 1, 2004).

"Hemicentetes semispinosus: Lowland Streaked Tenrec." http://info.bio.sunysb.edu/rano.biodiv/Mammals/Hemicentetes-semispinosus/ (accessed on July 1, 2004).

IUCN 2003. 2003 IUCN Red List of Threatened Species. http://www.redlist.org (accessed on July 1, 2004).

Shefferly, N. "Hemicentetes semispinosus." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Hemicentetes_semispinosus.html (accessed on July 1, 2004).

"Tenrec ecaudatus: Common Tenrec." http://info.bio.sunysb.edu/rano.biodiv/Mammals/Tenrec-ecaudatus/ (accessed on July 1, 2004).

"Tenrecidae—Tenrecs—Borstelegels." http://www.animalsonline.be/insectivora/borstelegels/common_tenrec.html (accessed on July 1, 2004).