Perceptive visitors have noticed that we had a very pregnant Naked mole-rat in our colony.
Readers of this blog may recall previous stories about our two queens, nick-named Elphaba and Galinda, and the November report of Galinda’s pregnancy. Pacific Science Center’s Animal Care staff was hoping for a small, successful litter but as the due-date approached, it was apparent that the litter would be large.
Sometime between 5pm closing on December 22 and 7am December 23, Galinda delivered twenty baby mole-rats. In a large litter the pups are competing for nutrients before they are born and not all are expected to survive. Certainly this was the case with Galinda’s offspring. Within hours, some of the smallest and weakest individuals died.
The first five days are always critical for mole-rats pups. Because of this, we are hesitant to announce the new litter until after this precarious period. In fact, none of the twenty pups from Galinda’s December 23 litter survived.
Now we wonder - what’s going on? Each queen now has healthy progeny integrated into the colony but both of their most recent litters have failed. We have scheduled a visit from our veternarian, Dr. Maas at Avian and Exotic Animal Hospital and will be taking a closer look at our husbandry protocols. Watch these pages for updates.
That really is odd! I hope all is well and that its just an unfortunate fluke, or that whatever it is can be resolved! I know most people look at you wierd when you say naked mole rat, but their survival is just as important as any other species! :)
ReplyDeleteThank you Ashley for the encouragement. It can be frustrating to work with this species because some of our assumptions based on other animals do not apply to them. But in spite of this loss, we have actually made some significant strides in improving the colony's health, and I have a lot of (guarded) hope for them in 2010.
ReplyDeleteThanks for the update - our family loves the Mole Rat exhibit. We have been following these health issues and check in on "the little guys" whenever we visit!
ReplyDeleteWhat are some of the assumptions that don't apply to naked mole rats?
ReplyDeleteI like your question, anonymous. Some of the assumptions we have had problems with over the years:
ReplyDeleteDosage for medications can't be calculated based on other rodents of the same size because mole-rats' metabolisms are so different. Some relatively benign medications can kill their gut microbes, which will kill the mole-rats.
Complete isolation of queen and pups makes sense from a hygene point of view but the colony will reject animals that they don't recognize, so workers have to be continually cycled into the pup chamber.
The queens are exerting dominance pressure on each other that we don't understand very well, and that are different from those of reproductive females of other species.
Perhaps the queens are "harassing" each other to the point that theyre are not able to carry a pregnancy successfully? Supposedly it is the same "harrassing" that normally keeps the other NMR's from reproducing on their own.
ReplyDeleteYours sincerely
Jesper K. Boesen
PS. "Harrassing" = continiously bumbing the nose against the others. Perhaps a study in the levels of stress hormones would be interesting and how they affect the pregnancies?
Actually an interesting experiment would be some sort of chamber emulating tunnel exits and above ground area as an barrier between the existing colony and a new temporary one. Too see if one of the queens and/or more of the other NMR's would try to split off and form a new colony. :o
ReplyDeleteBut thats probably not possible in an exhibition. :)
Yours sincerely
Jesper K. Boesen
Hi Jesper, good to hear from you. We miss your very thoughtful posts, which often spur new ideas for us. I will answer both comments in one.
ReplyDeleteRegarding the queens harrassing each other. Given our situation it seems like it must be the case, but we see very little sign of it. I've seen a lot of tooth fencing among workers but it actually involves mostly younger animals or large, known non-reproductives. The queens largely ignor each other or even seem mildly interested in each other's litters. If anything the lack of aggression on their parts is of note, and decidedly unlike reports from any other colony.
Regarding the above ground chamber, we have a simulated air hole in the form of a funnel over a large tube, which they can use as a "volcano" to kick debris out of. But we could probably simulate a real exit simply by leaving the lid open on one of the chambers. A very intriguing idea; I will bring this up at our weekly staff meeting and get back to our readers if we do it.
Hi again Antwatcher.
ReplyDeleteI don't know if my posts are so thoughtfull after all. I'm just born curious ;).
It's intriguing that you haven't observed the queens "battling" it out so far. As far as I've been able to read about NMR's the constant bossying around by a queen was supposedly the reason for only one reproductive female in a colony. Perhaps, as I was wondering, by inflicting higher levels of stress hormones in the workers.
Perhaps there is some kind of unseen "pheromone inhibitor" in a "true" dominant queen that supresses a workers ability to reproduce more than it is direct physical contact. AFAIK all NMR's are able to reproduce if separated from the dominant individuals?
Regarding the "experiment". I read up a bit on some studies that NMR's, even though theyre highly inbred, will mostly choose unrelated mates if given the choice. Additionally there are reports that they in the wild will sometimes exit their tunnel and move as far as up to 2 km above ground to try to find a new colony to join. Quite a frightening experince for a little pale blind hotdog even though theyre gutsy.
It would be interesting to observe this behaviour or any kind og above ground exploration in a more controlled environment.
PS. When reading one of these studies I thought of the poor grad. student watching molerats for hours on end through 8 months. So I thought about the feasibility of using an infrared camera for this. Put it above the colony and perhaps with the right tracking software it would be able to track the movement pattern of each individual of the colony (with markers on the animals) or atleast "traffic" patterns in a colony. Allthough you wouldn't be able to see how the individuals interact I thought it would be a great idea for a larger experiment with room for colonies to split, join or battle it (or what ever NMR's do) out in.
I've been giving these unsuccessfull litters some thought.
ReplyDeleteIt would be expected that a new queen would have a bit of a learning curve in regard to taking care of newborn NMR's but since both queens seem to be quite caring and have both successfully given birth that doesn't seem to be the case.
Would you happen to know whether the early deaths (within a day or 2) was caused due to a lack of milk?
I was thinking along the route that maybe the 2 queens are confusing not only for the pups but also the queens themselves. Theyre both or the wrong (non lactating) one trying to take care of the pups. Offcourse if you are isolating the queen that have been giving birth along with the pubs the point is moot.
The only other thing I can think off, besides a queen powerstruggle, would be some kind of outside influence. An infection? Somekind of malicious chemical in the plastic tubes or the concrete blocks?
Yours sincerely
Jesper K. Boesen
Lack of milk does not seem to be the culprit; we have found dead pups with milk in their bellies.
ReplyDeleteThere is a good chance that the colony does have a virus, something similar to the common cold in the degree of severity on adult and juvenile animals but possibly much more serious in the pups. In that scenario, the litters that survived did so because isolating them reduced the virus load, rather than because it reduced the stress of being handled.
We will be working with the vet to try and get a protocol that lets us knock back the virus to the point where, if the pups are raised in the colony, their exposure to it would be low enough that it should not be a cause of harm. Stay tuned.
Hi Antwatcher. I do hope the colony isn't suffering from something serious. You theory about a virus does sound very possible.
ReplyDeleteIt does still seem a bit strange that a virus would have claimed not only the weakest but all of the latest 2 litters very quickly and not be noticeable in the the adults. Especially if the pups do take nourishment. But perhaps NMR immunesystems are just relatively poor considering their isolated in burrows and non roaming nature.
On a lighter note you mentioned the common cold. Well on the smithsonians NMR webcam I did see a naked mole rat that seemed to be sneezing. So if yours are doing that and the noses red you might have found that culprit. ;) Or it might have been a case of hickups.
Out of curiousity Antwatcher. Do the naked mole rats dream? They certainly look that way when they rest on that webcam. :).
Yours sincerely
Jesper K. Boesen
Do animals dream is one of those quite challenging questions that delves into the history and philosophy of science. The burden of proof is weighted against animals dreaming - you would have to prove that they do.
ReplyDeleteI have read things that convince me that some animals dream, including studies of rodents that remember better if they are allowed to enter REM sleep after learning new tasks. But short of asking them, we really don't know if any non-human animal is conscious of dreaming, or ascribes "plot" to their dreams as we do.
As a human and fellow animal, I think they do, but that's not a very scientific approach.
I do remember the old family dog "dreaming". It was a somewhat strange mix of dachshound and a german wirehaired pointer. When dreaming it would make leg movements that was resembling either digging/swimming or running combined with sleepy barking. So I do think that atleast dogs dream of different aspects of whatever their world view is. Do naked mole rats dream? Well regardless of whether it's a dog or a naked mole rat dreaming I hope theyre sweet dreams of getting the best treats or finding the biggest tuber for the colony... ;)
ReplyDeleteYours sincerely
Jesper K. Boesen