Q&A 2012

This is a synapsid, and not a reptile. Yes, really.

This will be the last post at Synapsida before the New Year, so I thought I'd do something a little different this time. A lot of the hits on this blog are from Google searches, with a few from similar services like Bing. Often, the searches that bring people here are questions, and the blogger.com interface lets me see what those questions were. I don't check it religiously, so I'm sure there must be many questions that brought people here that I've never seen. But, just for fun, this week I'm going to answer some of the ones I have seen.

It's not going to help the people who asked the questions in the first place, of course. And, if anyone asks the question again, there's no guarantee they'll be directed to this page, rather than wherever they were directed before. But what the heck - why not, right?

So without more ado:

Is [X] a Synapsid?

This seems to be among the top two or three questions that bring people to the site. Is a cow a synapsid? Is a tiger a synapsid? What about a monkey? Or a kangaroo? And so on.

Mazes and Mole-Rats

The African mole-rats are a family of bizarre rodents, and one that I've discussed before. Their most famous member is the exceptionally weird naked mole rat, but the other, furrier, species are still pretty odd. They spend almost their entire lives underground, feeding on plant roots, and, as a consequence, are virtually blind. Famously, naked mole rats are 'eusocial' mammals, living in the style of ants or bees, with a single breeding queen and a number of sterile workers. However, some other African mole-rats live solitary lives, and others, while not as extreme as the naked species, are still strongly social.

We know very little about some of the species, but others have, on account of their peculiarity among mammals, been well studied. One of these is the Zambian mole-rat (Fukomys anselli). Much of the work on this species has concerned their hearing abilities. They turn our to be particularly good at hearing low-pitched sounds; the sort of noise that rumbles through the soil, and echoes through their narrow tunnels. Not only that, but they are also able to detect magnetic field lines, presumably to orient themselves in the absence of any cues from the sun.

How do Dolphins Sleep?

All mammals need to sleep. Quite why isn't entirely clear, although it may well have to do with saving energy, allowing the body to repair itself, consolidating the memories of experiences learned during the day, or any of a number of other reasons. What is clear is that it's very important, and that there's no way to avoid it in the long term. Indeed, it's not just mammals that do it, but also all species of bird, and probably just about every other creature with a brain, whether vertebrate or invertebrate. (Creatures without a brain, such as jellyfish, don't seem to sleep, although, to be honest, it's hard to see how you could tell if they did).

But sleep presents a problem, in that the animal is vulnerable while it's snoozing. This is why most mammals make dens of some kind to which they can retreat overnight - or during the day, if that's their preference. Dens, of course, can be remarkably varied, whether they are carefully constructed burrows, crevices in tree trunks, natural caves, or whatever, but most animals that live in the right sort of environment have them.