When we survey the coral reefs we are lucky to see hundreds of fish with beautiful patterns. The map pufferfish, emperor angelfish and lyretail grouper are some of my favourites. Of course these patterns are there for a reason; to attract a mate, provide camouflage or warn a predator. Equally pretty patterns are found all over the animal kingdom for these very same reasons. Less known however is how these patterns come to be formed. This is the story of how the puffer got his pattern.
Image courtesy of Jen Freer
The story begins with an unlikely person you may already be familiar with; Alan Turing. Turing was a celebrated British mathematician, who during World War 2, worked as a code breaker. He was part of a famous team at Bletchley Park who decrypted the German naval ciphers. But in 1952 he published an article with his theory on how patterns formed in nature. Only in March this year did experiments finally confirm the theory, 60 years after Turing’s death. Little did he know the impact it would have to the scientific community.
So what is this amazing theory? It is full of complicated formulae but the basic idea is very simple. Within cells there are two chemicals with opposing goals. The first wants to make more of itself, the second wants to stop the other from increasing. What is important is how the two chemicals interact and diffuse. When these chemicals diffuse at different rates, the generate instability and the formation of patterns.
Image courtesy of Megan Coughlin
This was Turing’s break through. That instability caused stable patterns over a space. He was the first to realise that biological systems could self-organize from an initially uniform starting point, influencing mathematical and theoretical biology.
Since then, computer models have advanced and improved the theory to simulate patterns we see in nature.
Animal like patterns similar to these have been computer simulated using the basis of Turing’s theory. Images courtesy of Jen Freer
From leopards to landscapes, spatial patterns in nature are ubiquitous. All underlying processes are essentially the same, regardless of the type of pattern being investigated; diffusion through an environment. In animals it is chemicals that diffuse. In landscapes it can be nutrients and vegetation. For example, in semi-arid lands, vegetation arises in predictable patterns due to water limiting plant growth. Animals themselves can be the diffusive force by migrating and dispersing through a habitat.
Landscape formations such as these ones in semi-arid land can be explained with Turing’s ideas.
So thanks to Turing for breaking through another code we now know how the puffer got his pattern. But the story does not end there; we can now use this information to investigate and understand other patterns at very different scales. From animal movements to landscape formation, patterns in nature are everywhere and I hope this helps you notice them a little bit more.
By Jen Freer, ARO on Tanzania Marine Conservation & Diving