Wednesday, October 21, 2009

Something to Chew On

In a recent blog article we mentioned that we provide the naked mole-rat colony with concrete blocks to chew on, and that the animals seem to treat these blocks as new frontiers that they guard and excavate. But can they really tunnel through?

Naked mole-rat’s teeth are big and scary looking, but they are not used for killing prey or chopping things in half. Naked mole-rats use their teeth for eating vegetables and tunneling, also for manipulating objects as we might use our hands. Their teeth are sensitive, versatile tools. They can handle newborn pups without harming them – or chew through concrete by taking many shallow, scraping bites.

This concrete block was flat when we put it in, and the colony quickly hollowed out the inside.

Animal Caretaker Dan Warner wanted something that would last longer and create less rubble. He experimented with concrete until he found a mixture that let the animals excavate, but not very quickly. Chewing concrete takes more than patience – it takes a lot of enamel. Luckily, the teeth of rodents including naked mole-rats, grow throughout their lives, replacing wear and tear so they can keep chewing.

Are they happy with their blocks? We believe that the blocks provide unique enrichment for the colony. The animals treat them differently than other areas. They routinely post an animal there - it is rare to see the block unstaffed by either an excavator or a guard, even when the rest of the colony is eating or sleeping. The mole-rats chew other parts of the exhibit as well – they chew up the edges of all their tubes, and scrape the inside of certain tubes, destroying them over time. But the concrete is by far their first choice.

Recently Dan observed some of our August 6 litter chewing on the concrete. We all see this as a good sign that they are developing well and using their teeth like their older relatives.

We are frequently asked if these cute little critters bite and does it hurt. Good question! Please tell us what do you think.


  1. Great update. With great pictures too.

    So they really chew through concrete. They sure are persistent probably bordering on stubborn. Then again it is in their nature.

    It's really nice to see you're stimulating the animals as much as possible. So that they can be themselves.

    Jesper K. Boesen

    PS. I'm trying to do a bit of lobbying for a NMR exhibit at one of our ZOOs here in Denmark. Have any good arguments I can make?

  2. So I was watching at the naked mole rat exhibit the other day, and I noticed something unexpected. I saw an adult naked mole rat with a piece of what appeared to be bedding in his mouth. He (or she) was very pointedly keeping this object in his(her) mouth and chewing at the concrete with it. What do you think was going on here? How would that help the chewing process? Thanks!!

  3. Hi Lauren, I have read that naked mole rats some times use "tools" like a bit of wood. They place it behind their teeth when they chew on something that leaves small particles behind. Perhaps to keep debris out of the mouth. It was one of the few documented cases of rodent tooluse. This sounds similar but not quite the same. Perhaps this is something new? :D

    Jesper K. Boesen

  4. Lauren, I am fairly sure that what you saw was the same tool use Jesper describes. I saw this behavior and it was very clear that the mole-rat didn't just incidentally have something in its mouth - it dropped the piece of bedding a couple of times and retrieved it before chewing again. I had not heard about the report Jesper read, but from my obsevation, the idea that the bedding was a dust filter seems quite reasonable.

    Jesper, my best arguments for having naked mole-rats are the following:

    They challenge us to question assumptions (such as that mammals are warm blooded and can't be eusocial).

    They inspire more questions than there are answers. Even fairly dignified adults are comfortable not knowing things about animals as unusual as these.

    They provoke discussion. They are active enough to keep people looking. People relate to them.

    They are not bothered by being watched. Their primary focus is on their own social world; the presence or absence of viewers doesn't really alter their behavior much.

    And their looks are a huge draw. People have opinions about them, and get pulled in. When you think about it, there are a lot of very beautiful animals, some sinister looking ones, some that are frankly silly, but very few are quite as odd as the naked mole-rat.

  5. Hi antwatcher and Lauren. I digged through my links list and found those regarding NMR tooluse.

    Heres a scientific report on it:

    And heres a summary of it with a good picture of it:

    Also thanks for the arguments Antwatcher. Lets hope I can convince some zoo people :)

    Jesper K. Boesen

  6. If you spray rataway fragrance it will stop the mole rat from chewing. non-toxic and non-poisonous

  7. Thanks for the fragrance suggestion, Rick. In a large open space where rodent chewing was a problem, this would be a good solution. In a closed colony such as ours, spraying a product in one location would probably permeate the whole habitat - a risk I don't want to take.

    Luckily, we are able to channel the chewing behavior into a few parts of the exhibit and use it to demonstate normal rodent behavior. It is a conversation starter for us, and enrichment for the animals. For the most part we view it as a bonus rather than a problem.

    But maybe rataway would work on the squirrels at my bird feeder...

  8. Antwatcher, You would only spray Fragrance of Rataway on a specific area, not the whole inclosure. you could paint it on with a small brush. People do it all the time in car engines,
    heating @ air conditioning equipment, computers, etc..

    Just where you do not want the little guys to chew.

    The little guys sure cute!

    The link is me doing the Rataway taste test.

  9. The little is look like so cute. But I think its not

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