Sense of smell

Fish that swim backwards – and other natural wonders

In the Zhuangzi, a collection of tales attributed to the eponymous 4th-century BC Chinese philosopher, a frog that lives in a well boasts about its comfortable way of life to a visiting sea turtle. When the turtle describes its own existence in the vast expanse of the ocean, however, the frog has no idea what to make of it. The story is, of course, a humorous parable about typical human limitations and the possibility of stepping beyond them. But it could serve almost as well as an introduction to Ed Yong’s new book, which confirms in rich detail what Zhuangzi intuited: the nature and range of different forms of animal