A Touching Naked Mole Rat

Here at the Pacific Science Center, we are always looking for ways to improve our guests’ experience, whether it’s through activities, interactive exhibits, or providing accessibility to all of our guests. We love exhibits where people can not only see, but also touch and explore with as well. However, with the exception of our Madagascar Hissing Cockroaches, that is not really possible with most of the animal exhibits. In fact, we specifically say that they are not allowed to touch the butterflies. So we are thrilled to announce a new addition to our department that you can touch. Welcome our brand new bronze naked mole rat!



Knowing how popular the naked mole rats are with our visitors, and how iconic their shapes are, Lead Animal Caretaker Lauren Bloomenthal wanted to render them accessible to everyone who visits. Who wouldn’t want to touch this cute statue? But even closer to Pacific Science Center’s mission was our goal of reaching diverse audiences by becoming more inclusive toward those who are visually impaired. For those guests who can’t see the mole rats, this becomes a way to experience them. For those who look but need more sensory data to really understand, the sculpture is an additional learning tool.

The idea quickly spread from the Animal Care department to the Exhibits team, where Exhibit Operations Coordinator Ashley Hollender helped bring the project to life. She invited Georgia Gerber, the artist who crafted our caterpillar as well as the turtles that live outside in our ponds, to work with us once again. As the project was moving along between Georgia, the Animal Care team, and the Exhibits team, we decided to enlist Stacy Thurston, a longtime volunteer who is blind. Stacy gave us invaluable feedback on the braille plaque which will accompany the bronze, as well as the location and features of the bronze piece.

Georgia came by the science center to get some up close, hands on time with our mole rats, as well as take numerous reference pictures. When she had sculpted the main design, she sent images back to our Animal Care folks for feedback. We loved it, but kept asking her to make the bottom teeth bigger. And bigger. And bigger. If there’s one thing we learned in this process, it’s that it’s all about the teeth.

The bronze mole rat is roughly two times the actual size of our naked mole rats. Even with the scale in mind, he has a large build compared to the average naked mole rat. If you study him, you’ll notice that he is carrying lots of his weight in his neck and chest. This means he is likely a disperser morph, like Hairless Houdini.

This project fell outside the normal scope of either Lauren’s or Ashley’s daily job. It entailed extra work and learning new processes. But they both really wanted to do it and luckily, our VP of Exhibits and Life Sciences, Diana Johns, believes in giving employees the opportunity to tackle this kind of project with the support they need to succeed. We couldn’t have done it without her.

While this is a rendition of a naked mole rat and its features is not an exact replication, Georgia’s artistic touch is what really brings our little bronze friend to life. Our bronze mole rat is cast from a limited edition mold. Ours is #1 in a series of 15. You, too, may have a bronze naked mole rat of your own.

Naming Contest

But wait! The bronze naked mole rat project is not yet complete. He is only missing one thing – a name! Here’s where we need YOUR help. If you’d like a chance to name our newest bronze addition, comment below with your suggestions. We’ll pick a winner next Thursday, October 17th.

And don’t forget to come by the Pacific Science Center and help us welcome our brand new bronze naked mole rat!

Addendum: October 15th

A braille interpretive plaque is now installed for our visually impaired guests.

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Life as a baby naked mole rat

On August 6th we will celebrate the one-year birthday of our first naked mole-rat litter since 2007. We’re so excited about this milestone, we’re even making them a tuber cake. In the past year, eight litters were born to competing queens, Galinda and Elphaba -a total of 136 pups in 12 months! Twenty-one have survived pup-hood and are growing into healthy adult naked mole-rats. Our colony has doubled in size in just one year!

This milestone started Life Science manager Sarah Moore thinking about the difficulties of mole-rat survival – even in captivity.



Two seemingly opposing things can be said of naked mole-rats: They are extremely long lived for their size and the first months of life are fraught with danger and a low probability of survival. If a naked mole-rat can survive the first few weeks of life, it has a good chance to go on to live a long and healthy existence. However, the challenges of those first days are often insurmountable. The last three litters born in our colony have had no surviving pups. The difficulties associated with making it through pup-hood have become increasingly apparent.


At birth, a naked mole-rat weighs less than 2 grams. Its eyes and ears are sealed closed and it can only drink milk. But it is not entirely helpless. From birth, mole-rat pups can right themselves if they fall over and wriggle through piles of older animals, working their way to the top of the heap. This is critical for them, as those who are unable to climb, risk being crushed.

It is during these first five days that we notice big problems – such as if the queen has not been providing milk or if the pups are unable to nurse. Pups are so tiny we can see milk in their stomachs if it is present. Without milk, the babies cannot survive.


Rarely do necropsy results from animals at this age point to disease. Indeed, often nothing can be concluded from studying pups that die in their first week. In fact, with large litters it is common for some of the pups to be more fully developed than others and it is rare that all of the litter members survive.


By the fifth day if all is well, the pups have grown significantly and are moving around the enclosure. They still need milk to survive and they are still highly vulnerable. But once they pass the five-day mark, we feel optimistic enough to post a birth announcement on this blog!

Between days five and ten, a second set of concerns begins. It is in this time that pups gain enough autonomy, but it is also during this time that they begin to pick up any viral or bacterial infections that may be present in the colony. We have found that frequent changes of bedding help reduce this risk. Even so, individuals with any inborn health problems may succumb during this week.


At ten days old, a mole-rat pup moves about easily, nurses well, and may be sampling food. Surprisingly, their first bites are often tough root vegetables rather than the soft dough balls we also provide. Baby mole-rats have teeth from the first day of their life. But their eyes remain sealed until their 20th day. This is less of a setback for tunnel dwellers than it would be for animals that evolved above ground.


Over time, naked mole-rat pups reach a third, difficult phase: The transition to a diet of entirely solid food. The cecal pellets passed from other workers are critical to the pups’ ability to navigate this change. Once they are eating solid food, they get to work cleaning chambers and taking on the everyday chores of a regular naked mole-rat. But that doesn’t mean they stop growing. Naked mole-rats usually take about 18 months to reach full size.


So why have some of our litters been successful while recent litters have be totally unsuccessful? There are likely a number of factors and we surely don’t know all of them. Aside from all of the inherent risks and tribulations of early pup-hood, it could be that our colony is reacting differently to new pups. Remember, half our colony has been born in the past year. Perhaps because of their youth and lack of skill in pup-rearing, the young pups are injuring the babies more than other adults would.


Additionally, our colony is the largest its population has ever been. Is there a limit to the number of individuals that can be sustained in a colony? Do the adults respond differently to new litters when the population has reached its limit? These are all questions we are asking now, and we will continue to post updates and new observations as they come. However, one thing is always certain with naked mole-rats: there will always be more questions.


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The Dropcam Adventure

On the evening of January 18th, all seemed calm in the world of Pacific Science Center’s naked mole rat colony. Some were happily munching away on their sweet potatoes and the rest were sleeping peacefully in their chambers.

By the next morning, there was a very different situation. The naked mole rats were roaming around in the outer enclosed area of their exhibit space. In the upper story of their exhibit, a security band was no longer securing a tube into its chamber. The mole rats had pushed the tube out of the chamber and climbed out.

Fortunately none of the fugitive mole rats was injured in the process. All the wandering animals received a thorough health check and were returned to their chamber space. The tube was re-secured. Other than Animal Care staff continuing to monitor the mole rat health, this would be the end of the story.

However with the advent of new technology and the far-reaching expanse of the Internet, we now have new ways to understand what is going on in our mole rat colony after hours. Thanks to our Naked Mole Rat Dropcam, we discovered that we have camera viewers around the world - in Finland and Germany to be exact. While most everyone in Seattle was fast asleep, our far away friends were just waking up to the after-hours antics of the naked mole rats. One German viewer wonderfully documented the naked mole rat expedition, noting the time, the number, and the behavior of individuals on their walk-about. Our observer also hypothesized where the breach might be located.

Readers may recall that this is not the first time our mole rats have escaped from the tube system within their enclosure. Each time, we take the information from the breach and try to prevent it from happening again. Now, the Dropcam gives us information that we couldn’t have before. We can go back and view the situation through stored camera footage and learn more about their behaviors. Previously, we could only see the aftermath. The earlier camera footage not only corroborates our viewer’s observations but also helps us solve escape problems going forward.

When trying to prevent the mole rats’ mischief, we look for their motivation to escape. We provide enrichment to entertain them. Part of their enrichment includes a dynamic system of chambers, particularly the second level, which makes for a bigger challenge for Animal Caretakers to secure. We secure chambers with rubber bands on the lids and non-slip mats underneath.

After this last escape, we worked with our exhibits team to refine the tube assembly. A routed groove allows a connection between the PVC joints so strong that even a human can’t break it.

Next, a wider base for our second level chambers should limit the tubes from being jostled loose. And as always, in the event that mole rats escape to the outer enclosure, they still have nowhere to go. That space is locked up tight with the same temperature and humidity as the chambers.

Besides giving us more information about mole rats’ nocturnal behaviors, this experience made us aware of the naked mole rat fans we have around the world. We absolutely loved hearing from our European viewers even if it took an unusual situation for them to share with us. In fact, we love hearing from all our mole rat fans. So please, check out both Naked Mole Rat Cam I and Cam II and share your stories with us. What have you seen our furless friends doing?


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Mole Rats At Work

Animal Care Volunteer Maurice Warner is a perceptive observer of our naked mole rat colony. Recently, he submitted the following story that helps explain our colony’s curious behavior.

Most of us think our naked mole rats are cute as they hustle about in their plastic tube colony, but you might be surprised to discover they’re often hard at work, each with a specific job to do. When I began working as an animal care volunteer, I assumed our exhibit colony was too small and too different from a wild colony of mole rats to reveal much about mole rat behavior. Turns out I was wrong.

Scientists who have carefully studied both wild and exhibit colonies describe a three caste social system. The “reproductive” caste includes the queen (or in our case two queens) and each queen’s one to three male consorts. The “soldier” caste is made up of the larger, non-reproductive animals, both male and female. The third, or “housekeeper” caste is composed of the smaller adults, again, both males and females.

Sometimes when I watch closely I notice mole rats doing their caste “jobs”. Also, I sometimes make small changes to the colony system to enhance mole rat behavior. If you watch the colony via our web cam you may see some of our industrious naked mole rats at work.

The housekeepers are the easiest to spot. Their jobs include keeping the tunnels clear for safe passage, and discovering new food sources. When I place some loose bedding material into one of our colony’s plastic tunnels the small animals quickly removed it – usually by walking backward and pushing the material out of the tunnel with their hind feet. (Did you know naked mole rats have hairs between their toes that make them more effective shovelers?) Finding new food sources is another very important housekeeper job in wild colonies. When they find food, they communicate its location to the rest of the colony through both vocalizations and scent trails. The housekeepers also carry small bits of food back to the nest chamber where it is eaten by other animals. When I place bite-sized pieces of carrot or grapes in the plastic tunnels, watch what happens! The larger animals rarely carry food back to the nest – they eat it in place. Carrying food is a job for housekeepers, not soldiers.

The soldiers’ job is to defend the colony against intruding snakes or mole rats from other colonies. Our exhibit colony never faces the threat of dangerous intruders, so it’s very hard to see our soldier attack. However, soldiers do not shy away from the occasional intruding Animal Caretaker when it’s time for weighing or changing bedding. And since they’re the larger animals, soldiers are the strongest diggers. Our exhibit colony can’t dig new tunnels but if I place significant obstructions in the tunnels – like a large cork that completely blocks a tunnel – the housekeepers are likely to first discover it and initially attempt to clear it away. But soon the larger animals move in from both ends of the obstruction and chew away at it in a frenzy that lasts until the obstruction is removed.

The reproductive caste mole rats, the queens at least, have one other important role in addition to producing new pups. The queen is the work boss. You may notice her conducting inspection tours to see what work needs to be done, or shoving other animals around. Laboratory research has demonstrated that colonies with the most “pushy” queens actually function most effectively! So she’s not nasty, she’s just doing her job.

If the naked mole rat caste system sounds more like bees than rats, you’re right! It is very unusual for a mammal that lives in groups to have differing behavioral roles that are not based on gender or age. Think about lions for example. If you’re curious about how mole rats got that way, you might want to do some naked mole rat research of your own. “The Naked Mole-Rat Mystery” by Jarrow and Sherman is a good place to start.

Unusual behavior is just one of the things that delights me about our naked mole rats. They’re not naked, not moles, not rats, and not insects either, but I love them!

Maurice Warner

Volunteers like Maurice observe interesting phenomena every day at Pacific Science Center. If you love science and would love to share your enthusiasm with like-minded people, consider volunteering in our Science Interpretation Program. Training begins soon.


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The Number One Question About Naked Mole Rats

Everything about naked mole rats is fascinating, and Pacific Science Center’s staff are eager to chat about them. Want to know about eusocial behavior? These mammals are a great example. Excited about the latest pups? So are we! Have you followed the adventures of the dispersing morph and want help finding him? Maybe we can help.

But before we can answer any of these questions, we have to address another question, one more urgent:

“Are some of the animals dead?”




We get this question daily, often several times per day. Adult naked mole rats have long life expectancies, and the death of a grown colony member is an extremely rare event for us. So why do we get so many reports of dead animals, and how can a casual viewer separate the living from the dead?

Naked mole rats’ metabolism is adapted to the low oxygen and stable temperature of an underground tunnel. Their respiration and heart rate are lower than one would expect for such a small animal. Thus, there are fewer signs of life to begin with!

Their greyish skin is a second contributor. To many people, the color has an unhealthy appearance, but pinkish grey is the natural color of a healthy naked mole rat.

Additionally, naked mole rats have a habit of sleeping in very relaxed positions. They often stretch out on their backs, with legs splayed in the air, for a long, motionless, deep sleep. Their favorite snoozing spots are over heat exchange ducts. Sleeping naked mole rats will tolerate other animals walking over them, and even kicking them, often showing little or no response.

Small wonder, then, that a grey, motionless, splayed out form would appear lifeless.


We have a few pointers for observing possibly “dead” mole rats before jumping to conclusions.

• If they are in a tube over a heat duct, watch them closely. Animals go here for their deepest sleep, and often lie motionless. When another animal crawls over them, you may see subtle signs of life – a twitch or flexing of muscle. That’s all you need to know they’re ok

• If they are pink and grey, this is a good sign. In the rare cases where an animal has been found dead, it was discolored, with purple extremities.

• Naked mole rats often rest on their backs and spread their legs out. This is a sign of relaxation. An animal that has died would more likely be rigid, rather than relaxed.

• Colony members are not tolerant of dead mole rats in their chambers. They would not ignore or walk over a dead colony mate, but would attempt to drag the animal to the most remote area of the enclosure. So if you see a mole rat being stepped on, it is probably alive.

• This is not a pleasant subject, but in the warm air of the colony, a naked mole rat that had perished would begin to deteriorate rapidly. Their stomach contents and skin would begin to fill with gases, and the animal would appear bloated.

We are always ready to check out any report of possible unhealthy or dead animals, but we also want to minimize the number of times we disturb animals that are simply resting. With so many people viewing our exhibits, it is often a visitor who sees a problem first and reports it. We hope with these criteria, that you have a better idea of when help is needed, and when a mole rat is just enjoying a nap.

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The Tale of Two Queens

Our last update of Pacific Science Center’s naked mole-rat colony announced that we had a new litter of pups born on August 26 and Life Sciences staff were observing a second pregnant mole-rat. As naked mole-rat colonies usually have just one reproducing female, we wonder, “What’s going on here?”



First a little history: Naked mole-rats are eusocial animals with one reproducing queen per colony. Our previous mole rat queen died giving birth October 22, 2007. With no mother to nurse them, her offspring did not survive. Soon after, the entire colony faced serious health problems until rigorous husbandry protocols were enacted.



It was not until August 2008 that another female became pregnant. Appearing bloated, she was nick-named “The Gassy Rat” before we realized that this female was, indeed, pregnant. Now named Galinda, her pups never appeared; perhaps she miscarried or reabsorbed into her system.

Next on January 19, 2009 Galinda gave birth to a small litter that did not survive. Shortly after, another pregnant mole-rat was detected, Elphaba who gave birth to her own litter of pups. From then on, we continually monitored the two females, which were staggered so that both did not give birth at the same time. No pups from either queen-in-waiting survived until August 6 when Elphaba successfully produced a litter of seven three of which are still alive today. We had to wonder what would happen next. Would Galinda return to being a regular mole-rat worker or would she compete for the colony’s crown? Meanwhile, Galinda was often observed being very attentive to Elphaba’s pups while she was obviously carrying yet another litter.

On September 20, Galinda gave birth to a brood of seventeen. Of these, seven have survived the critical ten-day milestone. So now what happens? Will we observe the colony splitting into two factions? Can two queens co-exist in one colony? Come visit Elphaba, Galinda and our entire naked mole-rat exhibit at Pacific Science Center . And continue to check back on this blog for updates on our colony’s activities.



Thanks to Lead Animal Caretaker Brianna Todd for her meticulous recordkeeping that provided the background of this story.

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Frequently Asked Questions

Frequently Asked Question #1: Can I ask you a question?


Answer: Yes! Please – ask another!

Animal Caretakers get asked a lot of questions – a lot of good questions! Here are some of our most popular.




FAQ #2: Are those snakes poisonous?


Answer: No, our snakes are not venomous. All of our snakes are constrictors, which means they squeeze their prey to death before they eat them. Our snakes don’t have to squeeze their food to death because we give them previously frozen rats. Dead prey is safer for the snakes because it can’t fight back and potentially injure them. Still, our constrictors squeeze their prey instinctively.

FAQ #3: Do you feed the naked mole-rats to the snakes?


Answer: No. The naked mole-rats are kept completely separate from the boa constrictors. Even though naked mole-rats sometimes die naturally, and the snakes would probably find them pretty tasty, we feel that we would be crossing a morbid line to offer our naked mole-rats up as food.

FAQ #4: Don’t sea anemones sting?


Answer: Not our Puget Sound sea anemones. You may feel a mild stickiness when you touch the anemone’s tentacles but that’s all. If you were a tiny sea creature, that stickiness would feel like a sting.

FAQ #5: Do naked mole-rats eat their babies? I think I saw one eating a baby!


Answer: Perhaps what you saw was a mole-rat eating a carrot? Unlike pet hamsters and other rodents in captivity, mole-rats rarely resort to cannibalism. In fact, when a mole-rat dies, it is more likely that the colony members bury them in the bedding.

FAQ #6: Are those the cockroaches they eat on “Fear Factor?”


Answer: Yes [sigh]. Madagascar Hissing Cockroaches are said to be delicious and high in protein. Some cultures consider them a delicacy. But we would never eat just any insect without thorough knowledge of its safety. Some insects are toxic and they all carry germs!

FAQ#7: How do the naked mole-rats know that the potty chamber is their bathroom? They can’t read the sign!


Answer: What do you think? Do you have a cat? Does she go in a litter box? Have you noticed dogs like to go where other dogs have gone? It’s because of the smell, right? And if you look closely, you’ll notice our naked mole rat potty chambers are isolated with only one entrance. This keeps the smelly room away from their living areas. Mole-rats have an excellent sense of smell!

FAQ #8: Will the hermit crab bite me?


Answer: Well, it won’t bite you … but it may pinch you, and then just enough to hold on. It’s more likely that when you pick up a hermit crab, the little critter will scurry back into his shell. It’s afraid of you!

FAQ #9: Where is the naked mole-rats’ water bottle? My hamster has a water bottle in his cage.


Answer: They don’t need a water bottle or dish. Naked mole-rats live underground in dry desert conditions. They have adapted to get all their moisture from their food. Because they live in cramped tunnels, the humidity is very high. Their need for moisture is not the same as your hamster.

FAQ # 10: What are these things? Axo …??


Answer: Axolotls, “ak-suh-lot-l.” Although they look like big tadpoles, axolotls are actually amphibians that never go through metamorphosis. You probably won’t find them in the wild – they come from areas of Mexico that are heavily populated and they are nearly extinct in nature. Axolotls are studied for their ability to regenerate their limbs.

Any other questions?


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Naked Mole Rat Enrichment

Viewers of our new naked mole rat cam may have noticed an occasional toy or treat in the exhibit chamber. Animal Caretakers call this “enrichment.” This is a term that frequently comes up in our blog posts and perhaps you’ve wondered, "What is enrichment and why is it important?"

Enrichment, as a whole, is something we give animals to bring out their natural behaviors and keep their brains active and the animals engaged. This can range from something on a small scale, such as hiding food for them to forage, or on a large scale, introducing naturalistic objects into their environment for them to manipulate and explore. In these ways, we cannot only enrich the lives of our animals, but also the experiences of our guests as they explore the world of animal life.

Our only mammals at Pacific Science Center, naked mole rats, are a huge focus for our enrichment activities. Their daily need for food and stimulation offer a fun challenge for Animal Care staff, who constantly find new ways to present a fairly simple diet. One way to enrich their lives in captivity is through food-based enrichment activities. These enrichments can range from blocking up tubes with solid tubers that they have to chew through, like they would in the wild, to small pieces hidden within their bedding to encourage foraging behaviors. We also like to make food-based enrichment fun for us too. Sometimes we create food sculptures, like a naked mole rat styled pizza or holiday shaped food that shows our love for them. While our mother told us to never play with our food, she never said that we couldn’t play with the food of others!

Another way that we keep these little guys challenged and active is through physical enrichment: Consistently changing their chamber and tube layout to keep them stimulated. We also provide them with dead ends. Instead of a tube leading into a chamber, it leads into a concrete block that allows them to keep their ever-growing teeth at a healthy shape and size. Physical enrichment also gives naked mole rats the feeling of working to expand the colony as they would in the wild.

The CareFRESH® bedding in their chambers also provides a great enrichment tool. With the bedding, naked mole rats rearrange their own habitat, filling certain chambers while emptying out others. They also keep their keepers enriched by kicking their bedding up into the exhibit through their volcano tube which Animal Care staff then have to vacuum up!

The mole rats are, surprisingly, also enrichment for themselves! Social enrichment is ever-present with our colony of 63 naked mole rats. Watching them interact, in person or via the web cam, reveals the unique eusocial dynamics and individual behaviors of our naked mole rat colony.

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