Hyraxes came up in one of my classmate’s presentations the other day.  I’d actually heard of them, but that was pretty much the limit of my knowledge. So as I always do, I decided to learn more about them, and make a blog post of it.

Hyraxes look a bit like rodents, but they couldn’t be more different. Well, I guess they could, if they were a potted plant or something, but my point is that in the mammalian family tree, rodents and hyraxes are pretty distant. In fact, hyraxes are most closely related to elephants, manatees and dugongs. What seems to have happened in the hyrax’s evolutionary history is this:

Hyraxes used to be the dominant form of herbivore in Africa, and were a diverse family (sizes ranged from a small horse to that of a mouse). Then the bovids came along – hyper efficient grazers and browsers that displaced the ancient hyrax from prime territory. So the poor hyrax had to find a way to make its life away from the magical African savannah. Some hyraxes simply became smaller and moved to rocky terrain, while others took to the water. The first group gave rise to the modern hyrax, while the second is thought to have evolved into elephants and manatees.

A hyrax with its tusks, grown from the incisors instead of canines (which hyraxes don't have).
A hyrax with its tusks, grown from the incisors instead of canines (which hyraxes don’t have).

A number of characteristics support this evolutionary tale – hyraxes and elephants are surprisingly similar. For starters, the hyrax’s reproductive setup is much like that of the elephant, in that they don’t have a scrotum (their testicles never descend out of the abdominal cavity), and the females have a pair of teats by their armpits, which is where elephant teats are located. Hyraxes also posses tusks, which are derived from the animal’s incisor teeth, like an elephants (other tusked mammals use their canines as their tusks). Finally, the claws of the hyrax are flattened, instead of being curved and sharp like in other mammals.

Hyrax feet are actually very specially evolved to grip the rocky surfaces in which hyraxes live. The soles of their feet are covered with sweat glands, which help keep the pads of the feet soft and elastic. There are also special muscles in the hyrax foot that make it act like a suction cup.

hyrax_feet

Being herbivores, hyraxes must have adaptations to allow them to digest plant matter. One of these are its molars, which are designed for some hardcore mastication to grind up plant fibres. Another is the hyrax’s stomach which is complex and multi-chambered, allowing for fermentation of plant matter by bacteria.

Hyraxes live in small groups, with a single dominant male that keeps out all interlopers. A single male can be in charge of multiple groups of females, which has to be a lot of work, as they each live in their own territory. Other, non-dominant males live on the fringes of hyrax society, and can only mate with young females (presumably when they are unguarded by the dominant male). The gestation period of hyraxes is seven to eight months, and females can have up to four young in each litter. To help feed her babies, the female has additional teats to the ones found by her armpits. These are in her groin area, where you’d normally expect to see teats.

A family of rock hyraxes, looking super cute.
A family of rock hyraxes, looking super cute.

Despite their innocuous appearance, hyraxes are a strange species, full of weird and wonderful traits. They might not be as charismatic as their elephant relatives, but they have their own species charm. Way to be, hyraxes.

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