Stripped and Strange: A Look Into the World of Naked Mole-Rats

Rodents are among the cutest animals in the world. Think about any cartoon you’ve seen featuring adorable woodland critters, most of them are rodents. Who doesn’t love the chubby cheeks of a chipmunk, or the tiny squeaking of a little mouse? Chinchillas are so fluffy it should be illegal. Hamsters and guinea pigs are often beloved family pets. When it comes to naked mole-rats, though, it’s a little different. When you look like some sort of nightmarish toothed sausage, you better hope your face is one a mother could love.

Are they moles or rats?

Naked mole-rats are a species of rodent native to the deserts of Eastern Africa. They are not related to moles and the only major trait their share in common is poorly developed eyesight. The name “mole-rat” comes from the fact that they spend almost their entire lives in underground burrows , while the “naked” part references their extreme lack of body hair. However, the way these two animals construct their burrows is very different. Moles have powerful front limbs with broad, spade-shaped paws tipped with long claws to dig, whereas mole-rats rely on their incisors. Almost a quarter of a mole-rat’s muscle mass is centered around the jaws They can shut their lips behind their teeth, creating a seal to prevent dirt and debris from getting into the animal’s throat.

Where do naked mole-rats live?

Naked mole-rats are almost never seen above the surface. They live in huge underground colonies that can number into the hundreds and span several miles beneath the deserts of Ethiopia, Kenya, and Somalia. Unlike other rodents, the social structure of naked mole-rats is very similar to that of insects such as ants, termites, and wasps. The colony supports only a single breeding female, the queen,  who can be nearly twice the size of a male mole-rat. There will be at most three breeding males, while all the other mole-rats are sterile and carry out functions that benefit the entire colony, such as digging new burrows, defending the colony from predators, searching for food, and caring for the young. This type of social structure is called eusociality. Queens typically produce one litter a year of an average of 11 pups, but in ideal conditions that can breed all year long and produce a litter roughly every 80 days or so.

Why are naked mole-rats so weird?

Naked mole-rats have a number of characteristics that distinguishes them from all other mammals and allow them to thrive in a harsh, subterranean environment. They are able to survive oxygen levels as low as five percent, including up to 18 minutes with absolutely no oxygen! When subjected to periods of stress, mole-rats can lower their metabolic rate by as much as 25 percent and drop their heart rate from 200 to 50 beats per minute. Due to the stability of temperatures underground, mole-rats do not regulate their own metabolisms. Instead, their body temperature matches that of the environment, much like in reptiles. Mole-rats cannot feel pain. Their skin lacks a certain neurotransmitter called Substance P, which is responsible for sending pain signals to the brain. It is believed that this evolved as an adaptation to dealing with high levels acid building up in the blood as a result of living in such a carbon dioxide-heavy, oxygen0-poor habitat. Perhaps the most unusual feature of mole-rats is their resistance to cancer. Mole-rat DNA is very peculiar. Several different genes combine to create a barrier against uncontrolled cellular growth, and they tend produce preteens with very few genetic errors. Their tissues contain a high concentration of a substance known as hyaluronan, up to five times the levels of other mammals. High levels of hyaluronan have been correlated to cancer resistance. An unexpected side effect of all these bizarre adaptations is that mole-rats live much longer than other rodent species. A lifespan of well over a dozen years is to be expected, but the oldest mole-rat on record lived to an astounding age of 32!

What do naked mole-rats eat?

Like most rodents, naked mole-rats are herbivores. There is not a great diversity of plant life underground, so their diet is almost entirely made up of tubers. A tuber is storage organ some plants develop for sequestering extra nutrients. Some are made of of the plant’s stems, other the roots. Potatoes and yams are types of tubers. Mole-rats tend to seek out particularly large tubers, often hundreds of times the weight of an individual mole-rat. Since the mole-rats eat only the inside of the tuber, this allows the plant to regenerate and thus provide food and water for the entire colony for an extended amount of time, sometimes months or even years. They are also known to consume their own feces in what is known as coprophagy.

What threats do naked mole-rats face?

One of the most numerous rodents in their environment, naked mole-rats are not considered endangered. While scientists have studied them due to their interesting genetics, they have not been exploited in any way by humans. Their primary predators consist of burrowing snakes, which are one of the few animals that can pursue a mole-rat in its burrow. When the eject excess soil from the burrows, they are at risk of being taken by birds of prey.

 

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