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.