Hedgehogs & Tenrecs - Who They Are and How They are Different Written By Gioia Kerlin
If it walks like a duck and talks like a duck, it must be a duck, right? Well, only sometimes.
African hedgehogs and both the greater and lesser tenrecs of Madagascar (setifer setosus and echinops telfairi, respectively) are quite similar in appearance. All are small, spiny, insectivorous mammals. They are all primarily nocturnal, they have small, beady eyes, and they can (in some species of tenrecs, anyway) roll into a protective ball when threatened. But they are not the same animal, nor are they all that similar genetically.
According to americazoo.com, our beloved little hedgefriends and their spiny counterparts the tenrecs are both members of the order Insectivora, along with shrews, moles, moonrats and colugos. Recently however, the scientific community has revisited this taxonomy and has proposed different classifications based on genetic criteria like molecular and DNA sequence analysis, rather than
shared physical characteristics. Most recent research places moonrats, shrews and colugos into separate orders. Golden moles and all species of tenrecs are now included within a grouping, or clade, that includes other animals such as elephants, hyraxes and possibly, aardvarks. This clade is known as Afrotheria (Afro- meaning Africa, and -theria meaning animal in Greek), which is considered a superorder. It is further narrowed down to Afroinsectiphilia (Afromeaning Africa again, and -insectiphilia, meaning insectivore).
According to this taxonomic system, our little hedgefriends belong to the clade Laurasiatheria (“Laurasia-” referring to the super continent of Laurasia, and -theria meaning animal) and are not considered to be close relatives of any species of tenrec. In fact, hedgehogs and tenrecs have evolved in isolation from each other. No hedgehog can be considered endemic to areas that tenrecs
naturally inhabit, and vice versa.
Cladistics, the hierarchical classification of species based on evolutionary ancestry, is considered by some to be controversial. It is built upon evolutionary theory rather than perceived similarities and differences between species so it is quite possible that it is a much more accurate way of categorizing organisms. For example, just because a fossa (a Malagasy alpha-predator) looks like a cat
does not make it a feline. A fossa is actually from the family Eupleridae and is much more closely related to the mongoose. So looks can be deceiving. “Tenrec” (tenrecidae) is a term used to refer to a family of approximately 30 different species of animals.
Some like the setifers and the echinops appear to be very similar to our African hedgehogs. Some tenrec species are carnivorous
rather than insectivorous and are aquatic with soft, dense fur and long flat tails (Potamogale velox). Others have spines that, like those of a porcupine, are released when a predator touches them (hemicentetes semispinosus), while some individuals of the tenrec ecaudatus species are basically bald. Some tenrecs are arboreal, some live in piles of debris and leaves, and others must live near the water. Some live for only two years; others have a lifespan of 14years or more. “Tenrec”, therefore, is a very
generic grouping that refers to many diverse species.
Some people think that tenrecs and hedgehogs are distant cousins. I would have to disagree. I, for example, have more genetic information in common with a chimpanzee than tenrecs do with hedgehogs. These animals are truly “apples and oranges.” In this article, I’ll be talking primarily about the tenrecs that are commonly kept by hedgehog lovers: The greater hedgehog tenrec (setifer setosus) and the lesser hedgehog tenrec (echinops telfairi).
Besides their DNA, tenrecs are different from African hedgehogs in other ways. They have obvious physical differences. While hedgehogs have small, paddy feet, setifers and echinops have larger, graspy feet and distinctly articulated “fingers” that they use for climbing and making their way through the underbrush. That is because setifers are semi-arboreal and echinops are fully arboreal.
In fact, once either species of these little guys grabs hold of your hand or arm, it can be difficult to extract them!
Other visible differences are their eyes. Hedgehogs have larger, more beady eyes while setifers and echinops have hardly any eyes at all.
That leads us to the next difference-- whiskers. Hedgehogs have relatively short whiskers, somewhat like those of a cat. But setifers and echinops have crazy-long whiskers that point in all directions and help compensate for their visual deficiencies. These
crazy little hairs help tenrecs feel where they are and find where they want to go. In addition to these sensitive hairs,some scientists have speculated that echinops telfairi use echolocation in the form of clicks to navigate their world. These clicks are inaudible to humans. If you hold a lesser tenrec very still and observe the ears, you will see them constantly twitching and circulating back and forth so perhaps there is a basis for this theory.
Another difference istheir tails. While hedgehogs have cute little pink, vestigialtails, greater and lesser tenrecs have only bumps on their bottoms.
The biggest physical difference between African hedgehogsand both echinops telfairi and setifer setosus has to
do with the anus and urogenital tracts. Whereas hedgehogs have different openings for each bodily function, tenrecs have a “one opening does it all” physiology, like that of birds, reptiles, amphibians, marsupials (for evacuation), and monotremes. This is very unusual for placental mammals, which normally possess two separate orifices for evacuation. The term for this opening is cloaca which means “sewer” in Latin. Also, tenrecs have a relatively low body temperature, so that males do not require a scrotum
to cool their sperm as most other mammals do.
Hedgehogs and tenrecs also have distinct seasonal habits, ways of protecting themselves, and personality traits that are different. While hedgehogs will most often roll into a ball and pop and hiss to discourage an intruder, setifers will generally face the threat head on, mouth wide open and teeth bared. Their philosophy is that the best defense is a good offense. This method of self protection can make setifers somewhat “bitey.” Not all of them share this tendency; some of them are gentle, amiable “cupcakes”
that don’t care if you cover their faces with kisses. But there are individuals who are unpredictable and can draw blood faster than you can say “ouch!” These individuals are often best handled with gloves. But in general, a person just needs to be aware of the animals’ personalities and handle them with due respect. Personally, I handle all my setifers with bare hands except when trimming toenails. That is the only time I use gloves and I have found through experience that it is a wise choice.
As for echinops they normally do not bite much at all. When they are frightened, their response is to run full speed away from whatever has scared them. This makes it somewhat tricky to control them in unfamiliar situations. These animals can run very, very fast, and are so small that the threat of losing them forever is great. I allow all my pokey-pets, except for the echinops, to free range in their bedroom. They are so small, flexible and fast they could disappear in the blink of an eye. Nevertheless in
general terms, tenrecs are calmer than hedgehogs. They have a slower heartbeat and habituate more quickly to human interaction.
Unlike hedgehogs, setifer setosus and echinops telfairi both go through torpor, an annual period of reduced activity, metabolism and food consumption. Torpor is not true hibernation because the animal wakes up to eat, drink and play, just not as often as normal. Torpor is not well understood by scientists. Those of us who keep and/or breed tenrecs have noticed a great degree of variation in our animals’ torpor patterns. Typically, torpor occurs in the colder months. For my animals, it normally begins some time in October, reaches its peak during late December through February, and then ends completely between March and May.
Other people have noticed that their animals become torpid in the summer months (which would be winter months in Madagascar).
Tenrecs can be fussy eaters at the best of times but often refuse all food except for insects while in torpor. Some animals go through a deeper torpor phase than do others. An interesting fact about lesser tenrecs is that they go through a daily phase of lower and higher body temperatures in addition to their annual torpor.
During the day, their bodies are cool, even cold, to the touch and they can act somewhat slow and dopey. At night, they warm up and become more alert and active. In the book The Tenrecs: A Study in Mammalian Behavior and Evolution, J.F. Eisenberg and Edwin Gould cite daytime body temperatures in echinops as 24-28 C (75.2-82.4 F), and late afternoon temperatures of 27.5- 37 C (81.5-98.6 F). Echinops’ bodies reach their maximum temperatures at around midnight according to this research. This does not happen with setifers as far as we know.
Another big difference between hedgehogs and tenrecs is that both setifers and echinops will secrete a milky white liquid from their eyes when they are in an unknown environment. They smear this liquid on things around them by rubbing their faces on objects like a cat will do. This is normal and does not mean that the animal is possessed! It seems to happen more in the late spring and summer months when they are more active.
It also seems that males do it more often than females. Although at least in setifers, the girls still secrete this “milk” but to a lesser degree. The secretion is a little messy but doesn’t hurt anything. Many tennies will most likely need to bathe themselves after rubbing on things. They are very cute when they take a bath! They will eitherlie on their backs or sit up like squirrels, licking their
hands and wiping their faces.
Last, although both hedgehogs and tenrecs self-anoint, they do it in different ways. Hedgehogs, as we all know, lick something they are interested in, work up a mouth full of foamy saliva, and then spread this saliva all over themselves by contorting and licking their backs, sides and heads.
Tenrecs are less messy. Tennies will sniff and lick things that interest them but, instead of foaming at the mouth like Linda Blair, they rub their little hands in the substance and pat it onto their backs and flanks.
So, as you can see, tenrecs and hedgehogs may look very similar but they are very different. They are both wonderful, fascinating animals. It is a privilege to know and care for them both but their genetics, personalities,physiology, instincts, and annual phases make them completely different animals. One can’t help but feel lucky to know both of them up close and personal!
Final note: I would also like to mention that some tenrecs are endangered species and their natural habitat is threatened daily by commercial activities in Madagascar.
Slash and burn farming methods, gem stone mining, illegal poaching, and other commercial endeavors are dangerously reducing Madagascar’s forests, which are also the habitat of many unique species, tenrecs included. If you purchase a tenrec, it is important to make sure you are buying a captive bred animal, not an animal that was taken from its native environment. Wild animals should remain in the wild whenever possible.
Sources:
"Afroinsectiphilia." Wikipedia. 29 Feb. 2008. 13 Apr. 2008
.
"Afrotheria." Wikipedia. 2 Apr. 2008. 13 Apr. 2008
.
Eisenberg, John Frederick, and Edwin Gould. Tenrecs : A study in mammalian
behavior and evolution . Washington, D.C.: Smithsonian Institution
Press, 1970.
"Eupleridae." Wikipedia. 15 Mar. 2008. 13 Apr. 2008
.
Fountain, Lesley. "Animal Research Library." AmericaZoo. 13 Apr. 2008
.
"Giant Otter Shrew." wikipedia. 28 Mar. 2008. 13 Apr. 2008
Kupitz, David. "Remarks on the Lesser Hedgehog Tenrec (Echinops telfairi)."
Tenrec Resources and Information. 30 Mar. 2008
.
"Laurasiatheria." wikipedia. 14 Mar. 2008. 13 Apr. 2008
.
"Tenrec." Wikipedia. 28 Mar. 2008. 13 Apr. 2008
.
Wed Sep 21, 2011 1:16 pm