The naked mole rat must be one of the strangest mammals in existence. They live in underground colonies like those of ants and bees, with a fertile queen lording over sterile workers. They feel no pain in their skin, they live unusually long lives, they can cope with chokingly low levels of oxygen, and they seem to be immune to cancer. Their sight is poor, they can’t control their body temperature very well, and their teeth jut out beyond their lips. And they look like wrinkled sausages.

Now, just when you thought they couldn’t get any weirder, we can add another bizarre trait to the naked mole rat’s extensive list: they have really rubbish sperm.

Gerhard van der Horst form