I've heard the phrase "it's so ugly that it's cute" used to describe a number of thing, including babies and pugs (the latter much to my girlfriend's chagrin), but it cannot be be more apt than for the Naked Mole Rat (Heterocephalus glaber). Prof. Justin O'Riain, my undergraduate lecturer and Honours supervisor at the University of Cape Town, described their overall appearance as "penises with teeth". He wasn't far off the mark, but there is just something so endearing about these little guys. They live underground anyway, and they're blind. So why should they care about their looks? This morning there was a last showing of the captive colony here at UCT before the animals are moved to the University of Pretoria. Members of the Biological Sciences Department were invited to come see the colony for the last time by the lady who started it all back in the early 1980s, Emeritus Associate Professor Jenny Jarvis. She has been leading ongoing research into these fascinating animals for 30 years, unveiling piece by piece their extraordinary lifestyles, physiology, and sociality. Research from these colonies has landed up in the most prestigious scientific journals, including Science and Nature. Naked Mole Rats lead almost completely subterranean lives, and their huge buccal incisors are the perfect tool that they need for all the digging that needs doing! Their skin is very thin and almost completely hairless, and hangs very loose on their body which gives them their wrinkled appearance. Having loose skin is thought to aid them in having tighter turning circles, as tension in the skin does not hamper them. Their bodies are almost translucent as a result, and you can actually make out some of their organs with the naked eye. Their eyes are vestigial, meaning that they are completely blind. However, they are not completely useless, as when the animals are alarmed they open their eyelids and sense movement of air across the corneas. This may alert them to a possible break in the burrow that needs attending to, or may signify the entrance of a predator. Individuals can live for up to 30 years, which is unheard of for a small rodent.
Naked Mole Rats are very social creatures, and can live in colonies of up to 300 individuals. The colony is comparable to the 'hive' of social insects. There is one queen who is the sole breeder and suppresses the other females, and non-breeding individuals (essentially the 'workers') help to raise the colony's young and collect food. The colonies are highly xenophobic, and will often kill other mole rats that wander into their colony. As a result, these colonies are highly inbred, with an 81% relatedness between individuals. To put this in context, you are only approximately 50% related to each of your parents (provided there was no funny business in the higher branches of your family tree). This high degree of relatedness explains why workers are content to tend for siblings rather than have their own young. The genes being passed on into future generations are, for all intents and purposes, mostly their own. This inbreeding explains why mole rats express this eusociality that is otherwise restricted to invertebrates (eusociality has been confirmed in 3 species of mole rats). Naked Mole Rats are native to the arid regions of East Africa, but they can be found all over the world in zoos. In fact, if you've seen a Naked Mole Rat somewhere in the world they are likely to have once been under Jenny's care, as animals from UCT have ended up in the USA, UK, Germany, France, Japan, South Korea, China, and Israel. Naked Mole Rats are in vogue for medical research as it has been found that they are highly resistant to cancer. It was originally thought that they were completely immune to it, and this discovery and possible implications for human medicine led to it being named "Vertebrate of the Year" by Science in 2013. However, this year two individuals in US zoos were diagnosed with the disease, indicating that the species is not entirely immune, but still highly resistant. Being able to see these animals up close was a real privilege. Most of the onlookers were in stitches watching these animals hurtling along their plastic tunnels, grappling and running over and under each other to get past. The queen constantly patrolled the burrow, presumably keeping all the other females in check. The instinct to dig away at the walls is so strong in the animals that they regularly scrape away at the walls with their teeth and then attempt to move the invisible sand behind them with their forelegs, much like a dog does when excavating your flowerbeds. Perhaps the funniest part for me was seeing what a penchant they have for ProNutro. I had heard of baby birds being brought up on the stuff, and I'll admit that I occasionally enjoy a bowl too, but to see these little rodents with their disproportionately large teeth and huge gapes going at a spoonful of the stuff was too much to handle. I'm sad to see them go, and I hope that they can keep contributing to our knowledge about the natural world at their new home up north.
1 Comment
16/11/2023 11:05:49
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AuthorI am a birder, biologist, and nature blogger. I post about my trips, informative tidbits, and things I think are interesting. Archives
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