Interesting Animals: Hyrax

For some reason, I thought I had already posted this.

A rock hyrax (Procavia capensis), one of several species of these unusual animals

The mammalian Order Hyracoidea includes only the several species of hyrax. They are small, weighing approximately four kilograms and being only between 30 and 55 centimeters in length. On first glance, most people would think that these animals are either rodents or very closely related to rodents. They even have one common name that heavily implies the relationship: rock rabbit. In fact the genus name Procavia implies that species is the ancestors to the cavy, also known as the guinea pig. This is, in fact, far from the case. The closest living relatives to the hyraxes are actually the elephants and sirenians (i.e. manatees and dugongs)! If you look closely at their feet in particular, you can see some of the resemblance. All modern phylogenetic trees confirm the relationship. This is one of my favorite examples of unexpected relationships in the animal world.

There are many convergent evolutionary traits seen between the hyraxes and rodents. Some of this can be seen when comparing the dentition. Hyrax species have incisors that are rather like those seen in rodents, and they also have diastema (i.e. gaps between teeth) in the same location as rodents. However, the incisors of the hyrax do not appear to be continuously growling like those of rodents (note the lack of tea-colored enamel and the more blunt overall shape). It is quite understandable that such assumptions were made.

These animals are foragers, feeding on various bits of plant life. In the rocky ears that the inhabit, they are even considered to be the dominant herbivore. The rock hyrax will use crevices in the rock as well as abandoned burrows for shelter. They have well-developed senses and are actually quite vocal little animals. Their social structure is that of a territorial male and up to seven females. They are also prey to virtually every local carnivore. For the rock hyrax, this includes eagles, lions, and African wild dogs, to just name a few. Despite this, the lifespan in the wild can be as long as twelve years.

Sources are Animal Diversity Web and the African Wildlife Foundation. Image is from Wikimedia Commons under a creative commons license.