Did you know naked mole rats can run as fast backwards as they can forwards?
Tucked away in a quiet corner of the Dallas Zoo’s Lacerte Family Children’s Zoo is the Underzone, which hosts two colonies of naked mole rats. Our keeper, Joby Davidson, gives us the inside scoop on what makes these tiny, hairless rodents so fascinating and important. In Davidson’s words, “Naked mole rats are not moles and not rats, but they are naked.”
Despite looking a little too naked for some folks, these fascinating creatures seem to break the mold in just about every way.
Why they’re important:
In the wild, they call sub-Saharan Africa home, where they provide essential ecosystem services, such as being a part of the local food chain and digging tunnels that help irrigate the land during rare rainfalls. They’re also becoming increasingly important for research in cancer, osteoporosis, joint studies and Alzheimer’s disease, because a complex sugar produced in their body makes them cancer-resistant. They could be holding the secret to the fountain of youth! Interested yet?
Take me to your leader!
Naked mole rats have a very complex social hierarchy, similar to ants and bees. This is the most defining aspect of how they DON’T fit the mold for most rodents. Each colony has one queen and one or two mating males, and the rest of the members are divided into different levels of workers, including diggers, food-movers, and warriors.
Additionally, age is an important factor in rank – older ones hold more authority. For example, while moving around in their tunnels, they constantly have to figure out how to get around each other if they’re going opposite ways. The solution? Whoever is subordinate passes below, while the superior crawls over.
Here’s another interesting behavior observed in naked mole rat colonies: if an older mole rat sees a younger one doing miserably at its job, it will tug on the younger one’s tail as if to say, “Just let me do it.” The younger one gets the message and scurries away while the older one takes over, presumably grumbling about “kids these days.
At the top of the chain, the queen runs the show. She is the only female with a specific scent (or pheromone) that lets the rest of the colony know she’s the one with breeding rights. A queen is typically pregnant for an average of 79 days and has a litter of 10-15 babies (or pups). It’s possible for her to get pregnant again as soon as 10 days after giving birth (count me out!), but the average is four to five months between pregnancies. In the wild, populations grow quickly because breeding can happen at a rapid pace, but it’s possible that naked mole rats may regulate their own population, because most colonies even out at about 75 members.
On that note, we’re leading the way in experimenting with birth control for naked mole rats. Because they breed so often and have relatively large litters, population control helps us keep track of how many mouths there are to feed and ensure that our colonies are a comfortable size.
We began this research more than two years ago, treating the queen with annual birth control. One of the biggest questions was whether she would continue to produce the pheromone that asserted her “nobility,” and if not, would another female step up and take the role?
It seems to be working so far. “The queen still acts like the queen in every way, except for breeding,” Davidson explains.
Currently, the Dallas Zoo has two separate colonies. The first and largest colony began from a single breeding pair and now boasts 47 members. The second sprouted off from the first in a situation where a second female challenged the queen and attempted a takeover. We quickly separated them, and she became queen of a new colony all her own, with 21 members.
With so many members, how do we keep track of each animal? Microchips! We began a microchipping program six years ago. Although zookeeper Davidson says he doesn’t know each of them individually, he’s pretty adept at picking out queens and several other notable members of the clan.
The only “cold-blooded” rodent
Here’s your vocabulary word for the day: naked mole rats are poikilothermic. This means they are incapable of maintaining their body temperature and are essentially “cold-blooded.”
They build several levels of chambers of varying depth, so the higher chambers are warmer than the lower ones. Our residents have separate enclosures that mimic those chambers, with varying levels of temperature. On average, we keep the temperature around 85° degrees, with about 70% humidity.
Several other techniques keep our naked mole rats thriving. Tunnels connect their different chambers. These tunnels have to be replaced fairly often though because naked mole rats’ teeth grow continuously throughout their lives, like most other rodents. These teeth are on the outside of their mouths, placed in a way that they can use them to dig their tunnels, but be able to close their lips so they don’t ingest dirt. Since their teeth grow constantly, the’re always busy wearing them down on their exhibit and tunnel walls.
Besides chewing on the walls, naked mole rats are exceptionally civil little beings. They have special bathroom chambers that are used only to collect waste. Sounds familiar, right? (Disregard if you still dig holes in the yard.) It gets a little weird after that, though. Naked mole rats are very close to blind, so they rub their own urine on themselves after using the bathroom as a way to distinguish themselves by smell.
Threats to naked mole rats
Although the current wild populations of naked mole rats seem to be pretty healthy, increasing droughts are likely to make it difficult for them to find the bulbs and roots they need to feed the colony. They are likely to establish colonies on farms, where they feast on cassava and sweet potatoes. If farmers perceive them as pests, they may double their efforts to get rid of the wrinkly rodents.
What you can do to help naked mole rats
Since the change in weather patterns worldwide is greatly influenced by the amount of heat-trapping gases in the air, we can help protect naked mole rats and other African animals in the comfort of our own homes. Reducing our energy use can have a positive impact on wildlife. Weatherizing your home, unplugging electronics, taking short showers are all easy ways to reduce your carbon footprint. You can also join the Dallas Zoo’s Wild Earth Action team to get involved in local, hands-on conservation efforts.
If you’re interested in meeting a queen, but can’t quite foot the bill to take a trip to England, come visit the Underzone in the Lacerte Children’s Zoo instead, and see for yourself the fascinating world of naked mole rats.