Swimming against the tide

As marvels of the natural world go, seahorses are way up there. They’re the only species in which the males carry and deliver tiny, fully formed seahorses, in broods ranging from five to 2500. They have no teeth or stomachs, and food passes through them so quickly that they must eat almost constantly to stay alive.

But today’s metaphor centres on seahorses’ fully independent eyes: they can look