Brooke Tremaine, of Balclutha Primary School, asks :-
Why are some animals camouflaged and some not?
Simon Pollard, a spider biologist at Canterbury Museum who is a RadioNZ science correspondent and the author of a number of books for children, responded.
Everytime I am in the tropics, I feel like all the animals I see are pretending to look like something else. Stick insects look like sticks, some butterflies look like dead leaves, some spiders look like bird droppings and some caterpillars have a face that looks like a snake. One of my favourite examples of animal camouflage is a wasp I saw in Sri Lanka. When it lands on vegetation it changes its shape so it looks like a dead wasp that is covered in fungi. And that is a good look, if you can fool a predator into ignoring you, because it not only thinks that you are dead, but that you are covered in mould.
Animals have evolved a startling array of features so they can hide from prey and predators. Any change over time, that makes you blend better into your background or look like something else, makes it more likely that you will survive, and will become more common in future generations. This is called natural selection and it is the engine that drives evolution. A wonderful example of natural selection at work happened during the Industrial Revolution in England in the nineteenth century. A light-coloured moth used to blend in with the light bark and lichens of trees and this camouflage made it more difficult for birds to see them and eat them. About two percent of the moths born were actually dark coloured and they were more likely to be seen and eaten by birds. However, as the soot from coal fires blackened the trees, the light moths were more visible to birds and were less likely to survive than the black moths. Consequently, black moths became more common because they survived and had dark coloured offspring who also survived.
Animals that are not obviously camouflaged, and may actually stand out in the crowd, like a bright red millipede, may have evolved an outrageous fashion sense because they want to advertise to predators that they are poisonous and not good to eat. It is not surprising that there are animals that have evolved bright colours to fool predators into thinking they are poisonous, when they are perfectly edible.