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Tenrecinae, known as the spiny tenrecs, is a subfamily of Afrotherian mammals within the Tenrecidae family. Tenrecinae contains five hedgehog-like species in four genera (Hemicentetes, Tenrec, Setifer, and Echinops), all indigenous to Madagascar. The common tenrec (Tenrec ecaudatus) also flourishes on Réunion, Mauritius, the Comoros, and the Seychelles, Indian Ocean islands where it has been introduced (Olsen 2013; Smith 2012).
Spiny tenrecs range from 80 grams to 2 kilograms (2.8 oz to 4.4 lbs) in size, generally larger than species in the three other tenrec subfamilies, and are mostly solitary and nocturnal (Garbutt 2007). Omnivores, they feed primarily on insects and soft invertebrates such as earthworms, though some species also eat baby rodents and frogs (Olsen 2013, Garbutt 2007). Barbed, quill-like spines are a distinguishing feature found throughout the Tenrecidae family. These spines are especially prominent on the coat of all five spiny tenrec species and are arranged much like the spines on a hedgehog (however hedgehog spines are derived from multiple hairs while tenrec spines are formed from a single modified hair; Olsen 2013, Garbutt 2007). When threatened, a spiny tenrec will curl into a ball, exposing its spines in self-defense. This similarity to a hedgehog-like life strategy is just one example of the considerable convergent evolution to other insectivore species for which the Tenrecidae family is well known (Olsen 2013, Garbutt 2007).
The genus of streaked tenrecs, Hemicentetes, is unusual in that its members produce sound with specialized row of quills that they stridulate, or rub together (Garbutt 2007; Davies 2011). Stridulation is thought to be a way for mothers and offspring to communicate. In contrast to other tenrecs, which are solitary, streaked tenrecs share burrows with related individuals (Garbutt 2007). The lowland streaked tenrec (Hemicentetes semispinosus) is also unusual in that it is partially diurnal (active during the daytime; Olsen 2013, Garbutt 2007). In addition, the barbed spines of this genus can detach and become lodged in an unlucky predator’s skin (Garbutt 2007).
The larger spiny tenerecs are hunted as a food and hide source and E. telfairi is successfully farmed on Réunion Island for meat, a practice that may spread (Olsen 2013; Harduin 1994; Tatayah and Driver 2000). Hunting does not appear to reduce population sizes of these species. The IUCN rates all five spiny tenrec species as “of least concern” on the red list of threatened species, since these animals are common within their limited distribution and readily adaptable to disturbed habitats, often among human habitation, and they breed readily (Jenkins and Goodman, 2013a,b; Olson and Goodman 2013; Vololomboahangy and Goodman 2013a,b). The common tenrac, Tenrec ecaudatus, is the most fecund mammal known. It can have a litter of 32 babies up to twice a year, and females may have up to 29 nipples (Garog 1999; Olsen 2013). The lowland streaked tenrec holds the mammalian record for shortest generation time: 25 days (Olsen 2013).
Spiny tenrecs are becoming more integrated into the Western world: several species, including the lesser hedgehog tenrac (Echinops telfairi) and the greater hedgehog tenrec (Setifer setosus) have become popular in the pet trade (Wikipedia 2013; Crittery Exotics 2012). Interestingly, however, due to the fact that spiny tenrecs are difficult to distinguish from hedgehogs, the US Department of Agriculture has banned their entrance into the US, because hedgehogs carry Foot and Mouth disease (even though tenrecs do not; Olsen 2013). The nuclear genome of one Tenrecinae species, the lesser hedgehog tenrec (Echinops telfairi), has been sequenced as part of the 29 Mammals Genome Project (Broad Institute 2013; Lindblad-Toh et al. 2011). The complete mitochondrial genome of this species had previously been sequenced (Nikaido 2003). This tenrec may become a model organism in science as its genome is explored, providing wider evolutionary diversity to the more conventional set of model organisms.