Sunday, 18 June 2017

Pinnipeds: Hooded and Bearded Seals

Hooded seal pup
Most of the species of seal found in the waters of the North Atlantic are roughly the size of harbour seals, with full-grown males measuring about 160 cm (5' 3") in length, and weighing around 120 kg (265 lbs); females, of course, are somewhat smaller. Of the three species that are significantly larger than this, the biggest of all are the hooded seals (Cystophora cristata). While not a patch on the largest seals of the Pacific, with males up to 270 cm (8'9") and weighting around 300 kg (660 lbs), they're still pretty hefty.

Hooded seals live relatively far north in the Atlantic, spending most of their time in cold waters northward from Nova Scotia to the coasts of Greenland and Iceland, and some of the remote islands that lie to the north of Europe. They are known to have four, relatively small geographic areas in which they do their breeding - the Gulf of Saint Lawrence, off the north coast of Newfoundland, the Davis Strait between Greenland and Baffin Island, and around Jan Mayen island east of Greenland. Although these appear to be quite distinct, there is no evidence of any significant genetic difference between the populations, and hence, no recognised subspecies of the animal.

Sunday, 11 June 2017

Age of Mammals: The Miocene (Pt 1)

Five years ago, I started a series of posts in which I looked at the world, and its mammalian fauna, during the time of the Ice Ages. My plans as to how I was going to do that changed quite rapidly, and the earlier posts aren't really in the same format that I later settled in to. Nonetheless, since that time I have covered not only the Pleistocene epoch of the Ice Ages, but also the Pliocene, which immediately preceded it. Yet, even taken together, these two epochs represent only a relatively short slice of the Age of Mammals.

We currently divide the Age of Mammals - the time since the extinction of the non-avian dinosaurs - into three broad periods: the Paleogene, Neogene, and Quaternary. The last of those includes only the Pleistocene and the brief, human-dominated, time since it ended. The Neogene, however, is also dominated by more-or-less modern kinds of animal, and it is further divided into two epochs: the later Pliocene, which I have already covered, and the earlier Miocene, which I haven't.

Perhaps the first thing to grasp about the Miocene is that, compared with the epochs that followed, it is remarkably long. It lasted, as currently defined, from about 23 million to 5 million years ago. That makes it over three times as long as the Pliocene and Pleistocene put together. As you might expect, the world changed far more over this timespan than it did during the subsequent epochs; we're not just talking a couple of million years here, but it a much more substantial chunk of time. It's only because it's so much further back that it makes sense to do this - we just don't have the same sort of fine detail available, since so much of it has been erased in the time since it all happened.

Monday, 5 June 2017

Are Horses Self-Aware?

I'd imagine that the first response from anyone who regularly deals with horses to the above would be "well, of course they are!" Your horse shows not just awareness and recognition, and is clearly a fairly intelligent animal, but there seems to be something going on behind those eyes. Horses seem, for example, to be aware of the emotional state of their handlers, and respond appropriately. There is surely more to their actions than simple, pre-programmed instinct.

And, if that is your response, let's face it, you're not wrong.

But then, awareness isn't a simple "all or nothing" phenomenon. All living things respond to their environment in some way; it's part of the definition of being alive. But even once we exclude say, tomato plants, there's still a massive gulf between jellyfish and humans. Once we get specifically to mammals, there is clearly more going in their mental and emotional states than is the case for, say, starfish or parasitic worms. But even then, there is no sharp line between the full consciousness of an adult human and the awareness of every other sort of mammal.

Saturday, 27 May 2017

Just What Is a Red Panda, Anyway?

Last week, as it sometimes does, the topic of red pandas came up in conversation. The person I was speaking to was well aware that red pandas are not very closely related to the more famous giant pandas... but he had no idea what they actually are related to. It occurs to me that, while I've often posted on the evolutionary relationships of closely related animals within the various mammal families, I've posted rather less about how the different families are related to one another. So, let's look at that, from the perspective of trying to figure out which mammal family it is that the red panda belongs to.

The red panda (Ailurus fulgens) was first formally described by Frédéric Cuvier, brother of the much more famous Georges Cuvier, in 1825. He gave it the scientific name that it still bears, which translates to "shining cat" because of what he thought it looked like. Of course, this was long before Darwin, so he wasn't suggesting that the animal was literally related to cats, since, like his brother, he presumably thought that all species were created independently. In fact, probably because of the bushy striped tail and the shape of the teeth, he instead placed it within the recently named raccoon family, the Procyonidae.

Sunday, 21 May 2017

Secret Origins of the First Hippos

Hippos are somewhat strange animals. They are large, amphibious, almost entirely hairless animals that are clearly related to the big hoofed herbivores, but do not themselves have hoofs. Still, it came as something of a surprise to everyone when, in the late '80s, it turned out that their closest living relatives were not pigs, as had previously been thought, but whales and dolphins. Which, granted, are also large hairless animals living in the water, but which (among other things) are anything but herbivorous.

Still, while whales and dolphins may be their closest living relatives, the latter have been around for a very long time, and it follows that the hippo lineage must have been around equally long. So, especially given that they aren't exactly small and easy to overlook, it's reasonable to expect that there should be a number of fossil species that are a good deal closer to living hippos than anything we have today.

And, indeed, there are.

Sunday, 14 May 2017

Pinnipeds: Freshwater Seals

Caspian seal
Seals live, generally speaking, in the world's seas and oceans. But, as I noted last time, there is one species of ocean-going seal with a population found in freshwater. This is the ringed seal of the Arctic and Baltic, one population of which became cut off during the last Ice Age and now has descendants living in Lakes Ladoga and Saimaa in Russia and Finland. Lake Saimaa drains into Lake Ladoga, which in turn drains, via the Neva River, into the Baltic, so while seals do not regularly swim in that river, the geographic isolation is, at least in theory, not absolute.

However, two other populations of ringed seals (or their immediate ancestor), became separated from their kin at a much earlier date. Unlike the Ladoga and Saimaa populations, they had the time and isolation to develop into entirely new species, notably different from their relatives out in the ocean.

Sunday, 7 May 2017

Compare the Mongoose

The mongoose family includes over 30 different species, found across Africa and southern Asia. That's excluding a few species of "mongoose" found on Madagascar, which were discovered, back in the last decade, to be more closely related to some of the other carnivores of the island than they were to the "true" mongooses on the mainland. On the other hand, it does include a small number of species that aren't commonly called "mongooses" in English. Ironically, in fact, it's one of these latter that's probably the most familiar of all mongoose species to westerners: the meerkat (Suricata suricatta).

(As an aside, the word "meerkat" is Afrikaans... which is a bit odd, since it means something completely different in Dutch).

Even when they aren't singing Hakuna Matata or trying to sell you car insurance, meerkats are common features on wildlife documentaries (at least they are in Britain; I can't speak for other countries) and in zoos across the world. In part, this is because they're rather cute, sociable animals, with complex, telegenic, lives that involve a lot of cooperation. But, while meerkats are probably the most social of all mongooses, they are by no means the only ones. Another example, for instance, is the banded mongoose (Mungos mungo), which lives in groups almost as large as those of meerkats.