Marvellous moles

To understand the underground moles have developed super sensitive faces...
21 May 2015

Interview with 

Dr Nick Crumpton, Natural History Museum, London


This week we're asking what's the most amazing animal? Talking to Ginny Smith, Nick Crumpton from the Natural History Museum, did his PhD on moles.

Nick - For starters, how about their strength? Now, these animals are pretty incredible. They are super strong. If you have a look at their arms, you open up their arms and have a look at how big the muscles are, they're absolutely ginormous. Now, their humorous bone which is the top of your arm, that's actually as wide as it is long. And that's all for muscle attachments. So, these guys are really, really strong indeed. Now, we know that some species of moles can exert a force that's 24 times their body weight. Now, that's like a 12-stone person. It's a little bit more than me, like moving a 1.8-ton block. Now in addition to that, think about where they live. These guys live under the ground. They live in tunnels. So, that not only means that you have to move all that soil out of the way. That also means that you've got to make a living where you can't see but also, where breathing is actually really, really difficult. We know that the concentration of carbon dioxide in tunnels is 10 times greater than it is at the surface. We also know that the amount of oxygen found down there is less than half what we're used to breathing. Now to deal with that, that means that moles actually have twice as much haemoglobin in their blood. So, haemoglobin is the stuff that makes your blood red and it's the stuff that actually soaks up oxygen into your body.

 Ginny - Moles are well-known for being blind. Being blind doesn't sound that amazing to me. What's so good about them?

 Nick - Oh Ginny, that's because you've got such amazing eyes. You are using them all the time and there are lots of other ways that you can find your way around without using the eyes. There are an awful lot of blind animals. But moles use their tactile sense.

 Ginny - How good is their sense of touch compared to say, yours or mine?

 Nick - The front of their face is more sensitive than our fingertips.

 Ginny - So, we've got a little demo to do to show you just how sensitive your fingers are and what it might be like to be a mole. What's your name?

 Gavin - Gavin.

 Ginny - And how old are you?

 Gavin - 9.

 Nick - So, I've got some stuff in this sack right here. We've got some objects and you're not allowed to look at them. So, I want you to maybe - look at the audience, they look like a friendly audience. That's good.

 Ginny - Close your eyes as well just to be sure.

 Nick - I want Gavin to use his sense of touch and try and work out what this object might be. Now first of all, we're going to use a part of your body that maybe you don't use an awful lot for touch and that's going to be your elbow. Gavin, show me your elbow. Yes! And then after that, we're going to see how good you are at working out what this object might be, using your fingertip. Now, I'm going to push this against your elbow and see if you can tell me what this might be.

 Ginny - Gavin, if you want to move your elbow around, you can do that and sort of try and feel what it might be. What can you feel?

 Gavin - It feels smooth. It's very tiny, some spikes.

 Ginny - Some spikes. Okay, any ideas what kind of shape it might be?

 Gavin - It might be like a circular cone shape?

 Ginny - He's not doing too badly. Shall we see how well you do with your hand?

 Nick - So, don't open your eyes and I'm going to put this in your hand. So, here you go sir.

 Ginny - Okay, now see how quickly you can tell me what that is, feeling with your hands.

 Gavin - It's like a type of car toy?

 Ginny - It's a car toy. A round of applause! So, once you were feeling with your fingertips, was that fairy easy?

 Gavin - Yes.

 Ginny - Do you think you ever would've got it with your elbow?

 Gavin - No, because my elbow is quite bigger than my hand.

 Ginny - No matter how many times you'd put that on his elbow, I don't think he ever would've got it. And yet, our fingertips work really, really well. So, why is that?

 Nick - That's because of the amount of touch-sensitive receptors we have on our fingertips. Now, in terms of moles, they have very, very sensitive faces. On the front of their face, they have some really, really special touch-sensitive organs which are called Eimer's organs. No other creature has Eimer's organs. We know that there's lots and lots of them. If you use a really, really high powered microscope and you look at the skin on the front of their nose, you'll see them, and they're little bumps, they're little mounds. We know that every single one of them is super, super sensitive and can tell the brain what's going on in that area. Now, in fact we know that the brain maps that whole front of the nose area. So, a tiny little shape, even if it's just brushing across the front of the face, they know what kind of shape it is. They know if it's edible. Now, this has taken into an extreme, in an amazing kind of mole called star-nosed mole. It has 22 fleshy appendages coming off either side of its nostril.

 Ginny - Fantastic! Well, I have certainly learned an awful lot about moles. What about you guys? Over to our judges now.

 Georgia - Thank you, Nick. I have a question. I completely agree with you. Moles are fantastic, but if they had to develop all these traits to deal with underground - the low oxygen, having to dig - why go in the first place?

 Nick - Well probably, because it's really safe because if you go under the ground, there are not very many predators. Big predators are going to follow you down there. And also, there's loads of food. If you go down before anybody else then you're going to have access to all those worms and all those beetles, and all those other things that are down there. So, it's a pretty smart move evolutionarily.

 Ginny - Let's get our scores from the judges now.

 Max - 8

 Georgia - 8

 George - 10

 Ginny - Early 10. I think it's about time we saw how the leader board is shaping up. So Heather, how's our leader board looking?

 Heather - Well, the sticklebacks were doing swimmingly with an amazing 21.5, but the moles have really dug in with their impressive 26...


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