Finally, it’s the post you’ve all been waiting for! For weeks, your mind has been reeling with animal facts and new questions, but one, above all else, has swamped your thoughts. So I’ll answer it now. That funny looking animal in my first post was a tenrec. A lowland streaked tenrec to be exact. So now you know. Tenrecs are a family in the order Afrosoricida, which contains the golden moles and tenrecs. The tenrecs are a diverse family of insectivorous (they eat bugs) mammals that live in Africa, and mostly Madagascar. Though most tenrecs appear rodent-like, they are actually members of Afrotheria, a group that includes elephants, hyraxes, and aardvarks.
Most of the cool facts about tenrecs occur in particular species, but there are a few things common to all tenrecs. In particular, the reproductive tract of tenrecs is very unusual. Tenrecs have what is called a cloaca, which is basically one opening when there should be two or three. So all fecal, urinary and sexual secretions go through the same tube. Birds and reptiles usually have cloacae, but its a pretty strange thing to see in a mammal. Another weird thing about tenrecs is their body temperature. Unlike most mammals, some tenrecs don’t maintain their internal temperature at a constant level, instead letting it drop when they’re resting. This seems really counterintuitive to me, since the definition of mammal in my head is linked to warm-bloodedness and a constant body temperature (which is not the correct definition of mammal, it’s just one thing I associate with them). Tenrecs actually have such a low body temperature that they don’t need or have scrotum – instead the testes are inside the body. Some tenrecs even keep up these temperature fluctuations during pregnancy – which leads to variable gestation rates since the babies can’t grow in cold temperatures.
So now some interesting facts about individual species of tenrecs. The picture of course was of a lowland streaked tenrec, which I pulled out of a book I have because I thought it looked funny. And it does, here’s a picture to remind you:
The lowland streaked tenrec is pretty cool. It’s got detachable quills it can shoot at predators if it feels threatened. The quills are also pretty funny coloured, so that’s another point for the streaked tenrec. But here’s a really cool bit: it uses a primitive form of echolocation (tongue-clicking) to locate prey. Echolocation isn’t unusual among mammals; bats and whales are the most famous examples. But a fair number of ground-dwelling nocturnal animals use simplified sounds to orient themselves and find prey (think of hunting for tiny insects, in the ground, at night. Using eyes just wouldn’t work). Lowland streaked tenrecs have another interesting sound adaptation. The tenrec vibrates its quills against one another to create sounds used for communication. This process (of rubbing body parts together to make sound) is known as stridulation, and the lowland tenrec is the only mammal in the world known to do this.
So what about the other species of tenrecs? Well, they are interesting too! The tailless or common tenrec, for example, can give birth to a mammal record of thirty-two young in one litter. Thirty-two! Can you imagine? Mammals usually keep their number of young pretty low, because we give birth to relatively undeveloped babies, which require care until they are capable of surviving alone. Birds are like that too; they look after their young until they learn to fly or swim or whatever, so they keep clutch size fairly small. With parents who invest little or no time in their young, the strategy becomes very different. Without mom or dad to protect them, kids are likely to be eaten, or starve. So instead of trying to protect their young these species (many reptiles and amphibians and fish) just lay a whole lot of them. This increases the chances that at least a few of the babies will make it to sexual maturity. Which is what makes the common tenrec so impressive – it lays lots of young and spends lots of time raising them. The female tenrec does have twenty-nine teats to help her out, but I still think she deserves a parenthood award.
There are many other interesting tenrecs in the family, but to go into each and every one of them is beyond the scope of this blog. For example, a number of malagasy tenrecs have adapted to a semiaquatic lifestyle, much like otters (they are called otter shrews). Tenrecs are a great example of convergent evolution, where a family of animals have evolved to resemble another animal through an entirely different evolutionary path. In the case of tenrecs, many closely resemble rodents, like hedgehogs and shrews, while others look a lot like otters. Tenrecs have evolved to fill those ecological niches that are exploited by rodents or otters in other parts of the world. Not too bad for a family of mammals that made it into this blog simply because I saw a picture that looked funny.