The Red Queen: Sex and the Evolution of Human Nature

by Matt Ridley

Even for microscopic animals, the bdelloid rotifers are peculiar. They live in any kind of fresh water, from puddles in your gutter to hot springs by the Dead Sea and ephemeral ponds on the Antarctic continent. They look like animated commas driven by what appear to be small waterwheels at the front of the body, and when their watery home dries up or freezes, they adopt the shape of an apostrophe and go to sleep. This apostrophe is known as a “tun,” and it is astonishingly resistant to abuse. You can boil it for an hour or freeze it to within I degree of absolute zero—that is, to -272 degrees Centigrade—for a whole hour. Not only does it fail to disintegrate, it does not even die. Tuns blow about the globe as dust so easily that rotifers are thought to travel regularly between Africa and America. Once thawed out, the tun quickly turns back into a rotifer, paddles its way about the pond with its bow wheels, eating bacteria as it goes, and within a few hours starts producing eggs that hatch into other rotifers. A bdelloid rotifer can fill a medium-sized lake with its progeny in just two months.