They're So Adolescent!

At a recent staff meeting, Life Sciences staff commented that the naked mole-rat chambers have been looking grubby lately, even shortly after a fresh cleaning. At first this was simply meant as a slightly rueful observation. But as we discussed it, it became clear that the behavior of one group of animals is creating most of the mess.



The youngest colony members are now as large as the smallest of the adults in the colony. As they transition from juveniles into fully active colony members, these animals are showing behaviors that will help them be accepted in the group.

To a human, some of these behaviors may sound odd. The youngsters go into the communal latrine area and roll in the waste material they find there. Then they run through the tunnels tracking this mixture of bedding and debris. Wherever they go, there is a mess.


What could be the social advantage to a young naked mole-rat in coating itself in liquid from a communal potty? The answer starts to form when we think about where they live. Naked mole-rats’ habitat is underground in near total darkness. In their tunnels, it is impossible to recognize colony-mates by sight. One of the primary forms of identification is odor. Animals that smell like the colony are accepted; those that smell different may be rejected or worse, attacked. So rolling in the most odor-intense area makes a certain amount of sense.

As babies and youngsters, the mole-rats may have been so unthreatening that the colony accepted them without much difficulty. But as they become larger, it is important to the older colony members to recognize them as friendly.


For readers who have never had the pleasure, we can try to describe the odor of the colony. Naked mole-rats get all the water they need from their food, so their urine is extremely concentrated. It is pungent but not ammonia-y. It has a top note of sawdust and mouse, with a musky base note.

In the harsh outdoor habitat where they evolved, leaving the colony is extremely risky. Staying in the colony is much safer – if you don’t mind the smell.


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Tricks & Treats

Join the party animals at Pacific Science Center this weekend and watch our naked mole rats celebrate Halloween! Costumes are encouraged but not required.

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Having a Ball!

It’s easy for us humans to get swept up in football season every fall, but have our naked mole-rats also caught the same football fever? After feeding our colony recently, one mole-rat was observed scurrying around from chamber-to-chamber-to-chamber with a little green ball in its mouth. While we watched we couldn’t help but be reminded of a NFL receiver running for a first down. Are we really witnessing naked mole-rat football?



First, we noticed one mole-rat with the green ball held firmly in his mouth as he scampered non-stop through the tubes and chambers, heedless of the other mole-rats.

When the ball carrier finally stopped to eat some food, another mole-rat took over. This ball-carrying mole-rat repeated the same peripatetic activity to the delight of our guests.


At one point, the ball was in a scrum between several other naked mole-rats. Eventually, “Hairless Houdini” emerged with the ball in his mouth. While the others were distracted with food and basic mole-rat sniffing behavior, Houdini took the ball, buried it in the potty chamber then nonchalantly returned to his chums. Game over!


As you may have guessed, the “little green ball” is actually a solitary grape that Animal Caretakers include in the food assortment that we give the colony. We’ve never seen them eat the grape, but they sure have fun playing with it.

As much fun as it is to witness this adorable game, we can’t help but wonder what’s going on in the mole-rats’ activity. Are they showing competitive behavior, performing a social function or merely having fun? What do you think?

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Our Most Recent Babies!

Readers might recall that our last article about our naked mole rat colony discusses the complexity of pup life and their survival. We were once again reminded of these facts when our two queens recently gave birth to litters within six days of each other.



On September 7th, Elphaba gave birth to eight pups. Of the eight, six were either stillborn or died shortly after birth. The remaining two died within three days without any signs of having been nursed.

Then, Galinda gave birth to 26 (!) pups on September 13th. All were extremely small and underdeveloped. Sadly, none survived their first day.

Here are some interesting observations:

• This six-day difference is the shortest time span yet between the two queens’ litters. Readers might recall that at one time their litters were born 45 days apart.

• Previous to the last two births, we’ve been able to accurately predict the queens’ “due date” – 90 days for Elphaba, 80 days for Galinda – making Elphaba 19 days late and Galinda just four days late.


If they both follow their historic trends, Galinda will give birth on December 2nd (day 80) and Elphaba will give birth on December 6th (day 90). Should some survive, this four-day difference will make the closest aged cousins in the colony. It will be interesting to observe how they interact and whether the colony treats the pups from each litter differently.

But there are a lot of reasons to suspect that more time will pass before Elphaba’s next pups –if any – are born. Why is Elphaba’s gestation becoming longer? Is this connected to increased competition between the two? Has something changed in their environment? Elphaba may not actually have longer pregnancies – more likely she does not get pregnant for the first ten days. Galinda may interfere with immediate mating and Elphaba "sneaks in" mating opportunities as she can. The queens have a receptive cycle that dictates when they can be pregnant. If Elphaba misses her first opportunity, the next will occur about 10 or 11 days later. If Galinda delays her yet again, it will be another ten days or so until she is again at a part of her cycle that allows her to become pregnant. With fewer opportunities to mate, we would see smaller litters spaced further apart in time.


As December nears, the Animal Care team will be busy preparing for pups. We want to provide the healthiest and most welcoming habitat possible for them. The rest is up to the two queens. Stay tuned!

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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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Colorful Characters

The following cryptic notes appear in the Animal Care log:

• Purple front was found outside of the chambers this morning. Everyone else was safe inside.
• Black back is definitely looking pregnant.
• Please observe blue/green front’s weight closely, he is looking thin.
• The new pups have caught up in size with brown front.

Who are these colorful characters?


A careful look at the naked mole-rat colony answers the question. The colors are markings the animal care staff uses to identify the colony members. Each animal is given a unique marking – a single color or combination of two colors, either on the shoulders (front) or the lower back.

By marking each animal, we are able to log their weight changes and behavior over time.

Gradually, this information helps us piece together important roles within the colony, and understand why individual animals behave in certain ways.

Some of the animals have distinct physical characteristics or behaviors that have helped earn them titles or descriptors beyond their color markings. Over time, it becomes possible for Animal Care staff to recognize some of the animals at a glance. But without the color markings, it would be harder to monitor their daily behavior or learn their unique physical traits.

We’d like to introduce you to some of our more standout naked mole-rats by sharing their color markings and nicknames.

Black back is one of the two queens. Her nickname is “Elphaba”. Elphaba’s weight ranges from 52 grams non-pregnant to 72 grams pregnant.

Purple/orange front, “Galinda”, is the other queen, who has produced the last successful litter. Galinda currently weighs about 60 grams, she can be much heavier during pregnancy.

Blue/green front is nicknamed “Skinny Guy”, due to his unusual body shape. His appearance makes him a likely candidate for the breeder male, who usually fits this physical description. Skinny Guy weighs 48 grams.

Purple front, on the other hand, is our plumpest animal, and is the dispersing morph. His nickname, due to frequent attempts to escape, is “Hairless Houdini”. He weighs in at an impressive 81 grams.

Brown front is nicknamed “Toothless” for probably obvious reasons. He was part of a litter born just before the colony experienced health problems in 2006/7. At 19 grams, Toothless and his two surviving littermates are smaller than other workers, and are now smaller than some of the pups born in 2009. Their development may have been slowed down by the same circumstances that caused other problems in the colony. Despite the absence of teeth, he still loves to gum on soggy apples and dough balls. However, it is possible that Toothless will always be small.

The next time you're visiting Pacific Science Center, see if you can locate these or any of the other colorful characters at living in our colony.

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Queen Galinda?

On Friday May 21, naked mole-rat Elphaba gave birth to a litter of 20 pups. These individuals were smaller than usual and did not do well; by Monday we had lost the entire group. Either because the pups were not viable or for more complex reasons, the colony did not give this litter the same care as it has for the last several births.




While this sounds like unfortunate news, it may not be. Naked mole-rat colonies normally have only one reproductive female, making ours the anomaly in having two. Most other exhibitors have predicted violent fighting between females, which perhaps still lies ahead. But maybe not.

If one female is more successful in reproducing, the other can revert to a non-breeding state. The ovaries and uterus of a naked mole-rat that stops breeding would become smaller, as in an immature female. Her behavior would become more like that of a worker and less like that of a queen. Yet should the primary queen be lost, she would be able to resume breeding once again.

At this point, we cannot confirm that one female has emerged as the queen, but we can be on the lookout. If Galinda is validating her status, we will see her engaging in dominant behavior towards Elphaba and possibly preventing her from interacting with breeding males. Some studies show that this, rather than the pheromones she produces, is what prevents other females from getting pregnant.

Interesting times lie ahead.

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Reflections of an Animal Care Intern

Ever wonder what it would be like to be an Animal Care Intern? Discovery Corp member, Kayla has had that very opportunity for the past 9 months. Below are Kayla's impressions of working on the Animal Care team.





I initially applied for the Animal Care internship to extend my knowledge and experience of the tide pool. But after I began doing all the tasks, I realized that exotic zoology would be a better fit for me. So even though I learned a ton about the tide pool, I actually ended up finding a field that I am even more passionate about!

I believe that the one thing I learned that will be most helpful in future school or career situations was independence. When I first joined the animal care team, I did not really know how to create my own schedule and do things without being told. But throughout the time I had with my internship, I learned how to plan my own day and be my own boss, even when I had superiors around me. The independence I gained with Animal Care will follow me with whatever I choose to do in life.



I do not think that there was much I was unable to do during my internship because I believe I took full advantage of every aspect of it. I learned about snake handling, feeding all the animals and improved my interpreting skills by learning tons of new information on such great animals! But I do have to admit, the one thing I would have loved to do before my internship was over is tide pooling. It looks like such a great experience to go out and actually see our tide pool animals in the wild.


Of all the animals I dealt with during my internship, the axolotls made me the most uncomfortable. In the very beginning of the internship they actually terrified me. I am not quite sure why, but the thought of putting my whole arm in a tank of axolotls horrified me. But I soon overcame my fear of them and finally began feeding them myself! I actually am quite fond of them now, and hope to own a couple in the future!



During the internship my favorite place to interpret was, without a doubt, the naked mole-rats. Everything about them fascinates me, from the different roles of the colony, to how they raise their young. Some days I would find myself interpreting there for hours. And on many occasions I found myself talking and researching about them when I was not even at work. Someday I actually hope to go to Africa and study them up close in their natural habitat.

I think the most important thing to share about my internship was that it was truly a life-changing experience. It helped me improve on tons of great skills and guided me to a career path that I am passionate about. I will carry the experiences I have had from this internship for the rest of my life. I hope that the next person takes full advantage of every opportunity given with their time in Animal Care, because I am truly grateful that I did.

We are grateful to Kayla for her enthusiastic and inspiring service in our program. The Life Sciences program has surely benefitted as much as she has from her time working in it. We wish Kayla every success in her future undertakings, and expect to hear great things from her.


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Mole-Rat Siblings

Pictured in the family portrait above are representatives from the three recent naked mole-rat litters born to Pacific Science Center.



The largest mole rat at the bottom of the picture is from Elphaba’s litter born on August 26, 2009, the first successful pups this colony has had in over two years. The mother gave birth to seven pups of which two still survive. These two remaining pups have thrived and grown to about 33 grams in the past eight months. As most of our adult naked mole-rats weigh between 50-60 grams, this means these guys are over halfway full-grown! Not too shabby!

The second-largest naked mole-rat (top left) is from the September 20, 2009 litter, which was the first successful litter for Galinda. From her litter of seventeen pups, six pups have survived and they are just trailing the members of the August litter in weight and size. They are now ranging between 24 and 32 grams. Our biggest problem is trying to tell them apart!


The smallest guy is from Galinda’s March 16, 2010 litter of nineteen. There are thirteen pups from that litter that are still alive and thriving today! We have not yet weighed them because they’re so small and we don’t want to injure them. However, they appear to have just about doubled in size since birth. They seem to be growing at a pretty healthy pace, comparable to the members of the older litters.

How big can our naked mole-rat colony get? Stay tuned because it looks like Galinda is pregnant again!


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Cecotropes

What is that naked mole rat doing? Pacific Science Center's mole rat colony provokes this question frequently, but never more so than when animals solicit cecotropes.



The cecum (pronounced see-kum) is a portion of the digestive system in some species of animals, located between the small and large intestine. When food passes into the large intestine, the indigestible fiber is passed through as normal feces. However, portions that still contain nutrients are pushed back into the cecum where they are broken down into starches, sugars and vitamins. This material is then passed as cecal pellets or cecotropes, which the animal reingests.

Yes, the animal eats them. To a human, this is a strange concept. But to a naked mole rat with a diet high in fiber and low in calories, every bit of nutrition must be captured. By recycling nutrients that cannot be absorbed the first time, the animal is able to survive on a diet that would not support many other species. You can often watch a mole-rat assume a curled up sitting position allowing their head to reach far enough to ingest their own pellets.

Cecotropes are more than just nutrient-rich pellets. They also contain beneficial live cultures which the mole-rats need to properly digest their food. Baby naked mole-rats do not yet have these microbes and need to get them in order to survive. So as they begin to eat solid food, they will solicit older animals and beg for cecotropes. Late in her pregnancy, when her mobility is limited, the queen will also demand pellets.

Mole-rats do not normally produce these pellets on demand, and donor animals may be seen jumping or shaking violently in the process of producing them. Often when pups are involved, it looks as though an older animal may harm a pup, when in fact it is helping.

The ability and need to produce cecotropes may be part of the reason naked mole-rats are eusocial. All mammals need nutrition from their mother in the form of milk. For mole-rat pups, cecal pellets are a second form of necessary nutritive care, and one that can be provided by any member of the colony. This ability gives the queen a shorter turn-around time to focus her nutrient store on producing the next litter, while workers continue to provide for the existing pups.

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(Another) Birth Announcement

On March 16, Galinda, one of our two the naked mole-rat "queens," gave birth to a litter of 18 pups. It is our policy to send out announcements of births until at least five days after the pups are born, as the first five days are a critical time period and many litters do not survive.

We are happy to announce that we still have pups.




As of March 23, 2010, there are 13 pups still alive in the colony, an indication that Galinda is producing milk and the babies are being allowed to drink it. Galinda has been observed nursing the pups every day, sometimes for extended periods. In a few cases we can see milk through the thin stomach walls of the babies. Some of the pups are gaining weight more rapidly than others, perhaps due to better competition for milk.

If the first week is challenging, so are the next 14 days. During that time the pups will learn to use their eyes and ears, and to eat solid food. We are cautious in our expectations.

On the other hand, with previous litters, our only success with rearing involved an extremely involved process of removing the queen and her litter from the rest of the colony and gradually reintroducing them. If the colony can rear the pups without this removal, it will allow them to function in a more cohesive manner and may help the two queens sort out which one should rule.

Stay tuned for more details!


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USDA Inspection

On March 3, the Life Sciences staff meeting was interrupted by a walkie-talkie call from the receptionist. A government inspector was here to see the naked mole-rats.


Pacific Science Center’s Animal Care program maintains permits from two completely unrelated branches of the United States Department of Agriculture (USDA). Our butterflies and some arthropods are permitted by the Plant Pest and Pathogen department. These animals are seen as possible threats to agricultural crops, and are monitored to prevent escapes.


Mammals, on the other hand, are under the jurisdiction of the Animal Care branch, which inspects mammal care facilities to make sure that animals live under adequate and humane conditions. This day, a USDA mammal care inspector arrived for an unannounced inspection of our naked mole-rat colony.


The mammal inspector looks at the animal’s housing. She is looking for signs that they have proper ventilation. Is food available to them at all times, or according to their species feeding habits? Is there water? In the case of the naked mole-rats, the answer is no. Our inspector needs to see evidence that we do not provide water because these animals are able to use the moisture in their food. Otherwise we can be cited for not providing for their needs.


Animals must be housed on surfaces that can be kept clean, and in enclosures that are safe from pests such as mice and ants. Our USDA inspector may ask for a closer look to see what measures we have in place to keep our animal’s housing clean – what disinfectants we use and our schedule for using them.


She checks the animals’ records. We monitor humidity and temperature twice daily and record weights, births, deaths and medical conditions of all the animals. The Avian and Exotic Veterinary Hospital provides a program of regular veterinary care and the invoices to prove it.


Inspectors want to see how food is stored and may ask how it is prepared. Our roots and veggies are kept in the refrigerator, and are peeled and diced before feeding. We mix nutritionally dense dough of baby cereal and ground rodent chow as a supplement.

At the end of the inspection, the USDA inspector sent us notification that we passed. “No non-compliance” was the complete text of our rating – the highest possible score!

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