The Case of the Missing Sengi

The rediscovery of a species of mammal thought "lost" for almost 50 years was a significant enough story this week to appear (briefly) on the front page of the BBC News website. I'm not sure how much further I can add to the BBC story in terms of detail, but perhaps I can put it into context, as well as providing it for those who may not have seen the original. So here goes.

To start with, what exactly is a sengi?

Sengis used to be (and often still are) called "elephant shrews". The term is falling out of favour because they aren't literally shrews, in the sense of belonging to the actual shrew family, although, as descriptive terms go, it's not a bad one. Since the late '90s most scientists, when they aren't using the more technical term "macroscelidean", instead use the Swahili name for the animal, which is also the one I'll stick with.

New Mammal Species 2014

Waiomys mamasae

New species of animal are discovered every day. That isn't hyperbole; I mean it literally. I'm not sure of the exact number of new species that were named last year, but it's in the thousands, and likely a five-figure number, at that. This is, you'll note, rather a lot.

The great majority, of course, are insects. "An inordinate fondness for beetles" and all that. Most of the ones that aren't are also invertebrates, typically small things like mites, spiders, or crustaceans. When we do look at vertebrates, most of the new ones are fish, with amphibians and reptiles not far behind. For instance, looking at the new species described in the daily journal Zootaxa (by no means the only source for such things, although it is one of the largest) on Friday 12th December 2014, I count seven beetles, two flies, three crickets, a frog, a salamander, a gecko, and (unusually) a bunting.

In fact, new birds are, if anything, even more rarely described than new mammals. But while while new mammal species are not discovered that often, there are still several each year. So, for this, the last post of 2014, why not look back at some of the mammals that were officially described for the first time this year? This will not be, by any means, a comprehensive survey, just a sampling, and I'm not even counting the various new fossils that have been described, but nonetheless, here we go:

Cold-blooded Mammals

Short-eared elephant shrew, another member of the family

Mammals are warm-blooded animals. That is, they maintain a consistent body temperature regardless of, and usually higher than, that of their surroundings. It is, after all, one of the defining attributes of being a mammal. Yet, while virtually all healthy mammals have no real difficulty in keeping their body temperature high, a great many of them don't always bother.

Probably the best known example of this is hibernation. Many animals living in climates with cold winters enter a long "sleep" when their food becomes scarce, and don't wake up until the following spring. But this isn't sleep of the sort that humans experience daily, but something much more dramatic. Their whole body shuts down to a minimal level of activity, and body temperature drops to only a fraction above that of their surroundings - essentially, they become cold-blooded. Of course, unlike reptiles and amphibians, they aren't doing anything much while they are in this state, so we shouldn't draw too many parallels, but they can't be truly said to be warm-blooded at these times, either.