Sunday, 21 May 2017
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
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
(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.
Sunday, 30 April 2017
These are the fifteen species of marmot (Marmota spp.), most of which inhabit mountainous regions, often above the tree line. Marmots are the largest of all squirrels, being at least twice the weight of, say, prairie dogs. However, the weight of marmots isn't necessarily the easiest thing to quantify, because it changes so much over the course of the year, which is in turn due to their need to bulk up before entering hibernation. And the reason for hibernation in marmots? Well, that brings us back to the crappy habitat.
Sunday, 23 April 2017
|Ribbon seal (male)|
Male ribbon seals are black, or very dark brown, with clear, wide bands of pure white fur around their necks, shoulders, and just above the hips. Females are medium-brown with light tan stripes, so the pattern is less striking, but it's still present, and in the same shape. Neither sex is born like this; even once baby ribbon seals shed their pure white fur at around a month of age, they are initially plain in colour, only fully developing the stripes by the time they are two years old.
Sunday, 16 April 2017
While we often tend to think that prehistoric animals tended to be larger than those alive today, this, was however, rather less true of whales, which have grown more or less steadily in size over the course of their evolution, perhaps in part to make it increasingly difficult for anything else to eat them. So, for example, the Pliocene killer whale (Orcinus citoniensis) was around 4 metres (12 feet) in length, barely more than half that of the modern species - although still quite impressive on a human scale.
Sunday, 9 April 2017
Obviously, reproductive anatomy is an important field if we want to really understand how an animal functions and behaves. Testicular size, for example, can tell us about its mating strategies. This is because the rule is not simply "the bigger the animal, the bigger its gonads". In order to gather a harem of receptive females around itself, a male has not only attract them to itself with suitably impressive antlers (or whatever) it also has to fight off rivals, and it's going to have to be big and muscular to do that. But if the females are sexually promiscuous, that's pointless. Instead, what you really need is to produce so much sperm that yours swamps that of your rivals. So, in those species, the males tend to be smaller, but their testicles larger (proportionately speaking). Alternatively, if your species is monogamous then neither of these things are much of a concern.
So male reproductive anatomy can tell us quite a bit. But you won't typically find, in most descriptions, is quite so much information on the female reproductive tract. There's probably some information on the shape of the uterus, which can relate to things like litter size, and maybe for a few other features besides, but it tends to be rather less than you'll find for the males.