Echolocation

Perhaps it is not surprising that bats, which sleep by day, feed by night and swoop through the darkness as erratically as moths, are among the least understood group of mammals. Yet one of the most poorly appreciated facts about them is their global success. They have a near universal presence across six continents and are amazingly diverse, with 1,500 species, representing almost a quarter of all mammals. We can blame our negative attitude towards them on a certain Victorian novelist. The representative of a British environmental group once recalled how they frequently received questions such as: ‘Do all bats drink blood?’ Here, fortunately, is the book to counter Dracula

In his satirical Devil’s Dictionary, Ambrose Bierce defined the ocean as ‘a body of water occupying about two thirds of a world made for man – who has no gills’. Bierce may have been right to poke fun at human arrogance, but he underestimated the importance of the seas. Averaging almost 3,700 metres (12,000ft) deep, the ocean constitutes around nine tenths of the habitable space on our planet. It plays a commensurate role in the Earth system, not least as an engine – a ‘blue machine’ in the phrase that also titles an excellent book by the physicist and science presenter Helen Czerski – that moves heat around the planet.