Kayleigh Flint of Balclutha Primary School asks :-

Why are elephants grey?

Jean Arnott, of Massey University's School of Veterinary Science, responded.

To date the most plausible reason for elephants being grey stems from the elephants need to regulate their temperature. Because they are such a large animals, they have a problem getting rid of body heat. The colour grey seems to be the best compromise between black and white. Black radiates heat well but unfortunately also absorbs it quickly. At the other extreme white reflects heat but is far less efficient at radiating it. Hence grey appears to be the best colour for large animals - and we do have grey hippos and rhinos which supports this theory.

Colour is sometimes used for camouflage, warning about unpalatability/toxicity or to lure a mate. However it is difficult to understand why an elephant would need to hide or even what animal it would need to worry about being eaten by. As for finding mates, elephants rely on a keen sense of smell and sounds.

Having read all this you may find yourself wondering why a small mouse is also grey. Remarkably the many coat patterns follow a single mathematical formula, which vary depending on the size and shape of the region where they develop. No pattern is formed on very small embryos such as the mouse. Slightly larger embryos will be stripped. A little larger and spots will result. Embryos that are too big result in no pattern (as in elephants).