ANSWERS TO CORRESPONDENTS: Which animal can see the widest spectrum of colours?

QUESTION: Which animal can see the widest spectrum of colours? And, while the human eye will respond to wavelengths of light from about 380 to 700 nanometers, mantis shrimp can perceive a range from deep ultraviolet to far-red and polarised light. Mantis shrimp often inhabit coral reefs, where distinguishing subtle colour variations can help them identify prey, predators and camouflaged threats. Polarised light photoreceptors enable shrimp to communicate via patterns on their bodies invisible to predators, and identify transparent or reflective prey. Nick Fletcher, Malton, North Yorks The Oxford English Dictionary cites early uses of ‘hard-pressed’ from 1562, used in contexts where people were under significant stress, such as in battle.