Tenrec

Lore & Background

All tenrecs are believed to descend from a common ancestor that lived 29–37 million years ago after rafting over from Africa. The split from their closest relatives, African otter shrews, is estimated to have occurred about 47–53 million years ago. The leading hypothesis for their arrival on Madagascar involves a small number of individuals crossing the Mozambique Channel on floating vegetation. Tenrecidae is one of only four extant terrestrial mammal lineages to have colonized and diversified on Madagascar. Tenrecs exhibit remarkable variation in form and ecology. The smallest species are shrew-sized, while the largest, the tailless tenrec, can weigh over 1 kg. They are among the few terrestrial mammals that echolocate, and unusual among placental mammals, they possess a cloaca. Their body temperature is low enough that they do not require a scrotum. Most species are nocturnal with poor eyesight but well-developed whiskers. Their dental formula varies greatly, and permanent dentition erupts after adult body size is reached. Tenrecs are omnivorous, with invertebrates forming the largest part of their diet. One species, Microgale mergulus, is semiaquatic. The tailless tenrec can have up to 32 young and females possess up to 29 teats, more than any other mammal. Some species are social, living in multigenerational family groups. The lesser hedgehog tenrec is increasingly popular in the pet trade and is one of 16 mammalian species selected for genome sequencing as part of the Mammalian Genome Project.

Reader's Guide

Tenrecs are significant as a prime example of adaptive radiation and convergent evolution on an island ecosystem. Their diversification into niches occupied elsewhere by unrelated mammals provides evolutionary biologists with opportunities to study adaptation over evolutionary timescales. The recognition of their common ancestry with other afrotherian mammals—including golden moles, elephant shrews, and hyraxes—was not established until the late 1990s, reshaping understanding of mammalian phylogeny. Their conservation is of concern due to habitat loss from deforestation, fragmentation, slash-and-burn agriculture, commercial logging, and mining. Five of the six threatened species depend on forest habitats. The lesser hedgehog tenrec's role as a model organism in biomedicine may increase research interest in the group.

Did You Know?

• Tenrecs are among the few terrestrial mammals that echolocate.
• The tailless tenrec can give birth to up to 32 young and has up to 29 teats, more than any other mammal.
• Tenrecs possess a cloaca, a feature more commonly seen in birds, reptiles, and amphibians.
• The word 'tenrec' comes from the Malagasy word 'tandraka', which may be related to the Malay word for porcupine.