Question: What colours represent reptiles?

Hayley Evers-King answered on 12 Mar 2013:

Hello, I’m not quite sure what you mean, but I can explain my work a little more and maybe that will help. We can use colour to tell us about what lives in the oceans, but not really to look at individual organisms. We first use the colour to tell us how much ‘primary production’ is in the ocean – this is kind of like looking at a field or a forest and estimating how many plants there are in that area. In the ocean, the primary producers (who take energy from the sun during photosynthesis) are called phytoplankton. Like land plants, they contain a pigment called chlorophyll – the way chlorophyll absorbs and scatters light from the sun makes plants look green. So when we look at the ocean we can measure how green it is to tell us how many phytoplankton are there – there are usually quite a lot, so although they are very small they can change the colour of the ocean quite a lot – sometimes they can even make it go red, but that’s another story!!

We can use this information to tell us a bit about the other things that live in the water too. We can use computer models to estimate how many fish/whales that ocean could support.

If we had a huge number of salt water crocodiles in a patch of ocean (1000’s of them maybe) you might be able to pick up their colour – which would probably be something like a greenish/brown, but I don’t think there’s anywhere where you get these sorts of creatures in big enough numbers to see them from space.

But satellites can be useful for looking at individual organisms too, in a slightly different way. In South Africa, we attach little tags to our great white sharks. These tags can communicate with satellites and tell us where the sharks goes, how deep it swims etc. We’re also now starting to use these tags to attach little instruments to animals as well. One of my colleagues attaches tags to seals and they can measure lots of things – temperature, how salty the water is and how much chlorophyll there is.