PEOPLE often wonder why mammals are not so brightly coloured as birds and insects.
The reason is that mammals are colour blind and birds and insects are not.
Vision involves two types of cell. Rod shaped cells deal with black and white vision whilst cone shaped cells deal with colour. Mammals eyes only have rods.
The eyes of birds and insects are not similar apart from the cells.
Birds have two eyes each with a lens and a receptive retina.
Insects only seem to have two, but these are rightly described as compound eyes.
Each can contain as many as 25,000 little lenses and so insects like butterflies have excellent vision, but should be compared to a jigsaw.
If insects had to see an optician the poor practitioner would soon be driven mad!
One thing is sure, insects such as butterflies are perhaps even more sensitive to colour than we are.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article