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.
I had no idea that a pregnant naked mole rat could reabsorb the unborn babies into her system. Fascinating!
ReplyDeleteThank you for your question, Anonymous.
ReplyDeleteAccording to Life Sciences Manager, Sarah Moore: "It is not uncommon for an animal to either reabsorb a pregnancy or abort early so that there is little mess and it goes unnoticed. This may have happened several times in our colony, as the queens became fit enough to become pregnant but were still not capable of bringing a pregnancy to full term."
Hi, these truely are some interesting (and cute) animals. I have a few questions.
ReplyDeleteDid you ever find out what caused the deaths of a portion of the colony?
I've seen multiple references to NMR "chirping" in communicating but also read up on how degenerative their hearing is. Are they really that vocal? And in that case how do they sound?
David Wood (Mill Mountain Zoo) and Raymond Mendez (Work As Play) have written a guide "HUSBANDRY STANDARDS FOR KEEPING NAKED_MOLE RATS IN CAPTIVITY". It is probably an older guide but perhaps these guys would have experience should you ever run into problems again with the colony.
Thank you in advance...
Jesper (Just another NMR fan)
PS. Sorry for poor english. It really isn't my native tongue.
Jesper, thank you so much for your thoughtful comments.
ReplyDeleteWe do use Husbandry Standards, which is still the best. However for our situation, there were bacterial issues that were not covered in the text.
In fact, our big fear was that our cleaning protocol to deal with infection meant cleaning well beyond the limits set in the husbandry standards, which call for retaining some bedding at all times to keep familiar smells going in the colony.
To break a bacterial cycle meant removing everything and using bleach. I was very anxious that this would impede their ability to recognize colony members by smell, but it didn't seem to be much of a problem.
Regarding sound, yes, the mole-rats have many wonderful sounds they make, which sound somewhere between chirping and the squeaks of mice. Some seem to be associated with certain chamber or location.
There is definitely a "guard" noise that only individuals near our concrete blocks use - the blocks are the area where animals excavate new tunnels,and are clearly viewed as different from other areas. Mole-rats also make fierce though tiny protest chirps when we handle them.
Mole-rat hearing is limited to a narrow range, and poor at determining location. Could these limits have actually driven the complexity of their sounds? If the colony can't sense where a noise is coming from, perhaps the noise has to contain more specifics than if they had good spatial locating abilities. Just a guess. At any rate, if their hearing were better, and thus their chirps quieter or higher pitched, we would be missing the pleasure of hearing them, as they are by no means loud to human ears!
Hi, Antwatcher. Thank you for the speedy and very informative reply.
ReplyDeleteI'm glad to hear that the colony is doing well again now. Well even humans have problems with bacteria. Even in hospitals so it's probably something that is only avoidable to a degree.
Did you keep the colony together in a separate location while cleaning their exhibit? That would probably have kept their smell the same?
Speaking of which I have to ask on behalf of my girlfriend. Do naked mole rats or their exhibit smell much?
Also thank you so much for the answer regarding the NMR sounds and communications. I have been reading as much as I could find on the animals that seaches on google could deliver. I've seen dozens of videoclips of them from livecams and youtube but it's hard to get any idea of their sounds when the NMR have radios in the background, crickets near their exhibit or an entire class of children running around (as some of the clips had).
I do think you have a point regarding the complexity of their communications. A simple warning noise would probably not help much if youre blind, doesnt know where it's coming from and whether it's a tunnel cavein or a snake.
Atleast if they can differentiate between those it gives the others better chances of surviving the threat. Or that is what I think.
Thank you for the replies :)
Jesper
Hi again. Sorry for all the questions it's just "awesome" to be able to ask someone who have direct experience in handling naked mole rats.
ReplyDeleteYou mentioned the location specific communications. Apparently the NMR's have a way better spacial understanding of where they are in the colony than I would have thought.
Do you think that more or less every location is identified by a certain smell? Perhaps even to the degree that certain paths between locations can be identified as well?
Thanks in advance again.
Jesper
Jesper, you ask great questions.
ReplyDeleteWhen we remove the colony for cleaning, we keep them all together in a couple of freshly disinfected chambers. While there is always the chance of them contaminating each other, they are in such continuous contact with each other all the time that it is doubtful any new germs are exchanged.
The colony has a strong and distinct smell, which is only apparent when we open up the doors into the enclosure -the public doesn't smell them except when we work in there. I think that's too bad. To me, the smell is part of the colony's identity and knowing that they use it to recognize each other helps me understand them better. Just like watching them is more informative than just reading about them, smelling adds yet another dimension! But if we let the scents out, the heat and humidity would also be lost. Alas.
I don't know whether they use smells alone to mark the locations of parts of the tunnel. They seem to have a mental map of where things are. They certainly spend time getting reoriented when we rearrange things.
They also use cues like the arrangement of tubes. A chamber with only one tube leading into it will rarely be used as a sleep chamber. It is either a latrine chamber if it is big enough, or a place to chew new tunnels if it ends in a concrete block. Sleep chambers are big, have multiple access sites, and are usually the warmest spots. Anywhere with air exchange from above is a place to post guards and also a spot to jettison excess bedding by kicking it out the vent (volcanoing).
They like to have multiple pathways - areas with only one way in and out become hot spots for any aggressive activity; we try to eliminate as many of them as possible in planning layout.
In setups with more vertical space, the elevation of chambers also determines how they are used.
Mole-rats have the ability to sense magnetic north and south too- that probalby helps.
So - long answer, but I believe the communication must be a descriptor that indicates the function of the area, and maybe its position vertically and on a north/south axix. That's a lot of information right there.
Hi again Antwatcher and thank you for another great reply.
ReplyDeleteRegarding the smell, I'd have to agree that it adds another dimension to experiencing animals. I seem to remember cleaning the elefant housing at a local zoo during a school trip. I never could quite look at elephants the same. :)
In the case of Naked Mole Rats it probably keeps people from trying to hold them as pets which would be cruel for such a social creature.
I didn't exactly mean they marked the different rooms with different scents but theyre probably able to quickly smell whether it is a room with a bit of fresh air (guard zone), food area, latrine or a nesting room. Even if they didn't know the tunnels fully.
You mention tunnels ending in a concrete block? Do they actually chew through these or try to?
How about the rest of tube setup and chambers do they chew through those as well?
Do you happen to know if specifically naked mole rats have been tested yet for magnetic sense? All I could find via google was a scientist wanting to test for it and some reseach confirming that regular moles have this sense. Or perhaps I misunderstoof the articles.
Again thank you for all your replies. I'm becoming kinda jealous at you guys for being able to see these little critters live. AFAIK there is no exhibition with NMR's here in Denmark. The closest ones are 500+ km away in either Sweden, Germany or England.
Jesper
Jesper, stay tuned for an article on the concrete chewing all things naked mole-rat toothy.
ReplyDeleteHihi, nice Antwatcher. Looking forward to it :)...
ReplyDeleteSurely can understand why these animals are a hit in zoos...
And again thank you for all your replies.