Marine life

Streamlined, musclebound, warm-blooded and with fins that retract into body slots like a switchblade so it can attain swimming speeds of more than 40 mph, the Atlantic Bluefin Tuna is a wonder of the marine world – the Clan Chief of the Scombridae, that can weigh up to 1,500 lb. It has long been prized by sport fishermen, from Charlie Chaplin to the dentist-turned-bestseller Zane Grey, and there is nothing tentative about a tunny strike. In 1927, after a four-hour battle with one eight-foot giant, Grey wrote: ‘If it were possible for a man to fall in love with a fish, that was what happened to me. I hung over

When we observe the ocean we rarely peek beneath its surface. As Helen Czerski shows in her lively and engrossing account of the physics of ocean spaces, we would not see much anyway. Sounds travel well in water, and blue whales talk to one another across thousands of miles; but light soon disappears, apart from the glow emitted by luminous fish. Historians of the oceans (myself included) have looked at how, when and why people have crossed the surface of these spaces, uninhabitable except in the security of a boat or on islands, such as those in Polynesia with which Czerski begins her book. But we need to dive deeper.