Katherine Rundell

They are not, in fact, hermitical: they’re sociable, often climbing on top of one another to sleep in great piles, and their group behaviour is so intricately ordered that they make the politics of Renaissance courts look simplistic. When a crab comes across a new shell, it will climb into it and try it on for size. If the shell is of good quality but too big, it waits nearby for another crab to come and inspect it. If that crab also finds it too large, it joins the first crab, holding onto its claw until a queue develops – it can stretch to twenty crabs, arranged in order of size from smallest to largest, each holding onto the next: a hermit crab chorus line. When at last a crab arrives who can fit the vacant shell, the first crab in line claims the new crab’s former shell, and there is a flurry of crabs climbing into their neighbour’s home. The crab’s abdomen is soft and vulnerable to attack while exposed, so the whole process takes place with astonishing rapidity.

Pliny the Elder​ was not an easy man. He reprimanded his nephew, Pliny the Younger, for walking instead of letting himself be carried, thereby wasting hours when he could have been reading. But in 77 ce Pliny made the hedgehog the focus of his attention, and produced one of the loveliest myths in natural history. ‘Hedgehogs,’ he wrote in his Historia Naturalis, ‘prepare...

A common swift​, in its lifetime, flies about two million kilometres; enough to fly to the moon and back twice over, and then once more to the moon. Weighing less than a hen’s egg, with wings like a scythe and a tail like a fork, they eat and sleep on the wing. They gather nesting material only from what’s in the air, which means that there have been accounts of...

The word​ iridescent comes from the Greek for ‘rainbow’, iris, and the Latin suffix, escent, ‘having a tendency towards’. Iridescence turns up in many insects, some birds, the odd squid: but in only one mammal, the golden mole. Some species are black, some metallic silver or tawny yellow, but under different lights and from different angles, their fur shifts...

In 1584​, as Ivan the Terrible lay dying, he called from his bed for his unicorn horn, a royal staff ‘garnished with verie fare diamondes, rubies, saphiers, emeralls’. Unicorn horns were believed throughout Europe to have magical curative properties; as late as 1789, a unicorn drinking horn was used to protect the French court, where it was said to sweat and change colour in...