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Lowland Streaked Tenrec (Hemicentetes semispinosus)

Lowland Streaked Tenrec (Hemicentetes semispinosus)

Despite appearances, this spiky creature was not lovingly crafted by Hieronymus Bosch. Instead it is a real animal–a lowland streaked tenrec (Hemicentetes semispinosus) which is a native of the wandering micro-continent of Madagascar (presently located off the east coast of Africa).   The little tenrec weighs only 200 grams (7 ounces) and measures 13-17 cm (5-6.5 inches) from the tip of its pointy bewhiskered snout to the end of its vestigial tail. The yellow-and-black creature is covered with scattered quills (some of which it can detach at will). The little animal lives in the eastern coastal rainforest where it subsists primarily on worms and small arthropods. It is active both by night and day.

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But perhaps you are asking just what a tenrec is to begin with (my word processor, for example, obdurately refuses to recognize the word). The tenrecs are a group of omnivorous (though largely insectivorous) mammals which live throughout Madagascar and sub-Saharan Africa. They seem to be descended from some basal line of edentate mammals—as evidenced by their low body temperature and by the fact that they have a cloaca (a multi-purpose orifice for excretion and reproduction). Across their range tenrecs evolved to fill many different ecological niches. Thanks to convergent evolution, various species of tenrecs look like mammals more familiar to us such as otters, opossums, rats, and shrews (the lowland streaked tenrec, for example, appears analogous with the insectivorous hedgehog) but these appearances are superficial. Tenrecs seem to be distantly related to other African mammals like elephant shrews, sirenians, and hyraxes. Their only close relatives seem to be the extraordinary golden moles (like Grant’s golden mole, the exquisite sand swimmer of the Namib Desert).

KONICA MINOLTA DIGITAL CAMERA

As you might expect the lowland streaked tenrec utilizes its quills to deter predators—namely the disquieting fossa and various other carnivorous Malagasy mongooses. The tenrec can pivot the barbed spikes on its back and neck into an upright crest. Thus armed, the colorful little animal charges boldly at predators–which must perforce retreat or contend with a face full of barbed spikes. The lowland streaked tenrec is also unique among mammals in that it uses its spines for stridulation—a violin-style method of producing sounds to communicate. Like a cricket, the lowland streaked tenrec vibrates its quills together to make a strange shivering chatter (useful for finding mates and communicating in groups). You can hear the strange noise in the peculiar Youtube video below.

Female tenrecs mature quickly and can reproduce in as few as 25 days after they are born. They give birth to litters of 3 to 7 young.

Grant's Golden Mole (illustration from Michigan Science Art)

Yesterday I spent some time describing the Namib Desert (as well as giving a brief overview of the entire nation of Namibia).  I did this not just because Namibia strikes me as one of the most striking landscapes on earth, but because the harsh habitat is home to a profoundly strange mammal, Grant’s Golden Mole (Eremitalpa granti), a solitary, nocturnal predator of the Nagib Desert.  Grant’s golden mole lives primarily in the Namib Desert but ranges as far north as Angola and as far south as the arid dunes of South Africa.

The golden moles are already strange animals.  The name “mole” is a misnomer: golden moles are not closely related to the true moles (which are insectivores) or to the marsupial moles of Australia.  Their taxonomical classification is presently unclear but they seem to be most closely related the tenrecs, a group of insect eating primitive placental mammals.  Tenrecs and golden moles both have unusual dentition (a critical feature to the taxonomist) and possess cloacas like birds.  It has been speculated that tenrecs and golden moles are closely related to the first placental mammals, but this may be a mistake. It is also possible that the tenrecs resemble the ancestral placental mammal of long ago whereas golden moles have evolved features which uniquely suit their desert environments.

Van Zyl's Golden Mole (Cryptochloris zyli) photo from "Professor Paul's Guide to Mammals"

Grant’s golden mole is a particular anomaly since it is so profoundly suited for desert living (which may have to do with the great age of the Namib Desert).  Grant’s golden mole does not make permanent burrows but literally swims through the sand. The creature has powerful claws for digging which have almost some to resemble “sand flippers”.  It can move swiftly underground and detect its prey (termites, scorpions, and lizards) through its profoundly acute sense of touch.  Its eyes have become vestigial and are covered with both skin and fur.  Because it burrows through fine particles of sand, its coat is incredibly fine and dense, its nose is a leathery wedge, and its ears have shrunk to tiny, tiny openings.

Grant's Golden Mole

Grant’s golden mole does not build burrows so it is not known how or where it raises its young.  Because water is so scarce in the Namib Desert, the golden mole does not drink: its kidneys are hyper efficient.  It also does not regulate its temperature in the manner of other mammals and it is capable of dropping into a suspended state during the days (when it digs deep down into the oxygen poor sand).  Grant’s golden mole requires large swaths of sandy desert for hunting.  It lives only on the shifting dunes.  With such a lifestyle you would think that it has escaped trouble from humankind, but you would be wrong.  The giant sand mines of Namibia are eating into its habitat and it is preyed on by feral cats.  In so far as we know anything about its numbers, we believe it is threatened.  Even in one of the most inhospitable places, humans are making inroads.

Grant's Golden Mole after a Successful Hunt (Minden Pictures)

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