Strange AnimalsQuick Answer: The lowland streaked tenrec (Hemicentetes semispinosus) is a small insectivorous mammal endemic to the eastern rainforests of Madagascar. It is the only mammal known to communicate by stridulation, rubbing specialised quills on its back together to produce ultrasonic clicks. Adults reach roughly 140 mm in body length and weigh 125 to 280 grams. Its yellow and black quills act as both warning colouration and active defence, and it feeds almost entirely on earthworms.
The lowland streaked tenrec looks like an argument between a hedgehog and a bumblebee. It is neither, and it is not closely related to either.
Tenrecs belong to their own family, Tenrecidae, within the order Afrosoricida. Their resemblance to hedgehogs is one of the cleanest examples of convergent evolution in mammals: two unrelated lineages arriving at spines, a pointed snout and an insect diet because those solutions work.
Etymology and Classification
The genus name Hemicentetes combines the Greek hemi (half) with kentetes (one who pricks or stings), a reference to the animal being only partly spined compared with fully spiny relatives. The species epithet semispinosus repeats the idea in Latin: half-spined.
The common name is descriptive rather than taxonomic. "Streaked" refers to the longitudinal bands of yellow quills, and "lowland" separates it from its montane sibling, the highland streaked tenrec ( Hemicentetes nigriceps ).
Classification:
- Order: Afrosoricida
- Family: Tenrecidae
- Subfamily: Tenrecinae
- Genus: Hemicentetes
- Species: Hemicentetes semispinosus
- Sibling species: Hemicentetes nigriceps , the highland streaked tenrec
Afrosoricida sits within Afrotheria, a superorder that also contains elephants, hyraxes, aardvarks and sea cows. That places the tenrec closer to an elephant than to the hedgehog it resembles, which is the single most counterintuitive fact about the animal.
The tenrec lineage is generally reconstructed as having arrived by rafting across the Mozambique Channel, then radiating into a wide range of body forms on an island with few competing mammals.
Physical Description
The lowland streaked tenrec is small, slender and unmistakable. The base coat is coarse black hair, overlaid with bright yellow quills arranged in stripes that run the length of the body.
A crest of longer quills sits across the neck and shoulders. These are the defensive quills, and they can be raised and driven forward independently of the rest of the coat.
Measurements:
| Measurement | Typical range |
|---|---|
| Head and body length | Average 140 mm, up to about 172 mm |
| Adult body mass | 125 to 280 g |
| Tail | Vestigial, effectively absent externally |
| Quill colour | Yellow to pale gold over black underfur |
| Litter size | 1 to 11, commonly 5 to 8 |
| Lifespan | Up to about 30 months in captivity; wild lifespan unknown |
The snout is long, flexible and highly sensitive, used to probe soft ground. The legs are short, and the animal moves with a shuffling gait rather than the bounding run of similarly sized rodents.
Unlike hedgehogs, the tenrec cannot roll into a complete ball. Its defence is forward and aggressive rather than passive.
Stridulation: A Unique Mammalian Signal
The lowland streaked tenrec is the only mammal known to communicate by stridulation. A patch of specialised quills in the middle of the back, distinct from the defensive crest, can be vibrated rapidly against one another.
The result is a train of high-frequency clicks, much of it above the range of human hearing. The mechanism is common in insects such as crickets and grasshoppers, and essentially absent elsewhere in mammals.
What the stridulating organ does:
- Produces broadband clicks, with substantial energy in the ultrasonic range
- Operates by friction between modified quills rather than by vocal cords
- Is thought to help mothers keep contact with their young
- Is distinct from the defensive crest quills in both position and structure
The leading interpretation is that stridulation serves as a contact call. Family groups forage together in dense leaf litter where sightlines are short and scent trails are quickly disturbed, and a directional short-range signal solves that problem.
This creature generates conventional vocalisations too, such as tongue clicks that some researchers propose help with basic orientation. Evidence for true echolocation in tenrecs is substantially weaker than for bats and the ability should not be described as established.
Defence and Anti-Predator Behaviour
When threatened, the tenrec bucks its head and drives the neck crest forward into the attacker. The barbed quills detach readily and lodge in skin, muzzle or mouth.
A predator that takes a face full of barbed quills tends not to repeat the attempt, and the quills are difficult to remove once embedded.
The yellow and black pattern may serve as a warning to predators.
A natural predator is the fossa ( Cryptoprocta ferox ), Madagascar's largest carnivore. People also capture them, sometimes with dogs.
Diet and Foraging
Earthworms dominate the diet to an unusual degree. The tenrec is close to a dietary specialist, supplementing worms with other soft-bodied invertebrates found in leaf litter and topsoil.
Foraging is done by probing damp ground with the flexible snout, then extracting prey with the front teeth.
Recorded diet items:
- Earthworms, the primary food source
- Insect larvae from leaf litter and soil
- Other soft-bodied invertebrates
- Occasional small fruit, reported but not a significant component
Earthworm dependence binds the species to moist forest floor habitat. Soil drying or leaf litter removal removes the food base along with it.
Social Structure and Family Groups
Most tenrecs are solitary. The lowland streaked tenrec is the conspicuous exception, living in multigenerational family groups that can number in the low dozens.
Groups share burrow systems and forage together, and this sociality is thought to be linked to the stridulating organ, which is used to keep contact within foraging groups.
Burrows are long and shallow, with nesting chambers lined with leaves. Entrances are often plugged with vegetation during the day.
Reproduction and Development
Breeding is tied to the wet season, when earthworm availability peaks. Gestation lasts roughly 55 to 58 days.
Litters are large by mammalian standards, commonly five to eight young and occasionally as many as eleven. Young develop unusually quickly.
Development timeline:
- Birth: young are born without spines, which begin to develop within the first 24 hours
- Around 18 to 25 days: weaning begins
- Around 35 days: females can conceive, an exceptionally short interval
Sexual maturity within a matter of weeks is exceptionally early for a tenrec. Combined with large litters, it lets the population respond quickly to good conditions, which suits an animal with a short lifespan and heavy predation.
Torpor and Seasonal Activity
The species enters torpor during the cooler, drier months, when earthworm availability collapses. Body temperature and metabolic rate drop substantially.
This is not the deep multi-month hibernation seen in some other tenrecs. Lowland streaked tenrecs typically remain capable of short bouts of activity, and the depth of torpor varies with local conditions.
Tenrecs in general are notable for poor thermoregulation compared with most mammals, with body temperature tracking ambient temperature more closely than is typical. That flexibility is an energy-saving strategy rather than a deficiency.
Distribution and Habitat
The species is endemic to Madagascar, occupying the eastern rainforest belt in the north and east of the island. It is found nowhere else on Earth.
It occupies low to moderate elevations, with the highland streaked tenrec replacing it at higher altitudes. The two species have been found together at least once, in Mahatsinjo Forest.
Habitat requirements:
- Moist tropical forest with deep leaf litter
- Soft, damp soil supporting earthworm populations
- Cover for shallow burrow systems
- Tolerance of some disturbed and secondary growth, including secondary forest and agricultural land
That tolerance for degraded habitat is genuine and is part of why the species is not currently considered threatened. It is not unlimited: the animal still needs damp ground and litter.
Conservation Status
The IUCN Red List currently assesses the lowland streaked tenrec as Least Concern, citing a wide distribution, presumed large population and tolerance of modified habitat.
That assessment should be read carefully. Least Concern describes current status, not immunity. Madagascar has lost a large share of its original forest cover, and deforestation continues.
Pressures on the species:
- Forest clearance for agriculture, including slash and burn cultivation
- Habitat fragmentation isolating populations
- Capture by people and dogs near settlements
- Hunting for food in some areas
A species confined to one habitat type on one island has no fallback if that habitat goes. The current listing reflects that the forest still exists, not that the species is secure in the long term.
Tenrecs and Convergent Evolution
The tenrec family is a textbook radiation. From a single colonising lineage, Madagascar's tenrecs produced forms resembling hedgehogs, shrews, moles and even otters, filling ecological roles that elsewhere belong to entirely different mammal families.
The lowland streaked tenrec is the hedgehog-analogue branch of that radiation, but it is not a hedgehog in miniature. Hedgehogs roll up, tenrecs attack. Hedgehogs are solitary, this tenrec is social. Hedgehogs do not stridulate.
Convergent evolution explains the spines. It does not explain the stridulating organ, which has no counterpart in any other mammal and appears to be a genuine one-off.
Photo: Frank Vassen, Lowland Streaked Tenrec, Masoala National Park, licensed under CC BY 2.0.
Frequently asked questions
The lowland streaked tenrec (Hemicentetes semispinosus) is a small insectivorous mammal endemic to the rainforests of eastern Madagascar. It has black fur marked with bright yellow quills and feeds mainly on earthworms.
Despite looking like a hedgehog, it belongs to a separate family, Tenrecidae and its resemblance is convergent evolution rather than close relation.
It rubs together a patch of specialised quills on its back to produce high-frequency clicks, a mechanism called stridulation. The clicks appear to help family groups stay in contact while foraging in dense undergrowth.
This is the only mammal known to communicate by stridulation. The method is otherwise typical of insects such as crickets and grasshoppers.
Not to people. The quills are a defence against predators, not a venomous weapon and the animal is small enough to sit comfortably in a cupped hand.
If handled roughly it will drive its barbed neck quills forward, which can lodge in skin, so it is best left alone in the wild.
Earthworms form the bulk of the diet, with other soft-bodied invertebrates taken from leaf litter and damp soil. The long flexible snout is used to probe the forest floor.
That diet ties the species closely to moist, intact rainforest habitat.
They live only in the eastern rainforest belt of Madagascar, at low to moderate elevations. The species is endemic, meaning it occurs nowhere else on Earth.
Habitat loss across those forests is the main long-term threat to the population.
References
- Information in this entry draws on the IUCN Red List assessment for Hemicentetes semispinosus, the standard reference literature on Madagascan mammals including Garbutt's Mammals of Madagascar, and peer-reviewed work on tenrec stridulation and acoustic communication published in the behavioural and zoological literature.
- Measurements are given as published ranges rather than single figures, because body mass in particular varies substantially with season and torpor state. Developmental timings follow captive and field observations, which differ somewhat between studies.