• Question: What are rhinos horns and elephants tusks made out of? please answer my question :)

    Asked by katiemcgorryy to Aled, Ellie, Fiona, Kev, Willem on 11 Mar 2014.
    • Photo: Kevin Arbuckle

      Kevin Arbuckle answered on 11 Mar 2014:

      Elephant tusks are made of ivory, which is a tough material made of lots of minerals and other things, mostly calcium phosphates (similar to bone and tooth enamel) and magnesium.

      On the other hand, rhino horns are actually made of a protein called keratin. Keratin is also the protein that makes up hair, nails, hooves, and the scales of snakes and lizards!

    • Photo: Fiona Heesen

      Fiona Heesen answered on 11 Mar 2014:

      Hi katiemcgorryy,

      To the best of my knowledge Kevin is right – they are made out of two different materials, ivory and keratin. I had no idea that keratin was also a protein that made up the scales of snakes! How cool.

      Thanks all!

      Fiona

Comments

  • Photo: katiemcgorryy

    katiemcgorryy commented on :

    Oh okay thankyou! How come that our hair and nails are quite weak, but elephants and rhinos horns are so tough? Why are they different if they are made up of the same thing?

    • Photo: Kev

      Kev commented on :

      It’s related to the structure of the material – how hair vs horn is built up using keratin. In the rhino horn, the keratin is really tightly compressed (squished together) which makes it really hard, and the whole structure is much bigger than a single hair.

      You can think of this like paper. You might think paper isn’t very strong, and indeed you can easily tear a sheet of paper. But if you put 5 sheets together and hold them tightly together, you’ll find it much more difficult to tear it. If you have 20 or more sheets of paper squished together then it becomes practically impossible to tear the bundle – it’s just too tough.

      Another example of how structure can be really important in determining the strength of something is carbon. Carbon is an element that makes up lots of things (including a lot of our body). Carbon (and only carbon) also makes up both diamond and graphite (the stuff you get in pencil lead), but diamond is remarkably strong whilst graphite is very weak and ready breaks up, which has the handy benefit that you can write with it when you use a pencil. The difference is that in graphite, the carbon atoms are stacked in layers with each layer only weakly connected to the layers above and below it, so they can be easily broken. In diamond, the carbon atoms are each tightly bonded to 4 other carbon atoms to make a very strong shape that is difficult to break apart. There is more information on this example here: https://www.enmu.edu/services/museums/miles-mineral/diamond.shtml