Naked mole-rat

Wrinkly, pink and almost hairless, the naked mole-rat looks unfinished, but it is dressed for life in underground tunnels. Its lips close behind its big front teeth, so it can dig with its incisors without getting dirt in its mouth. Workers form a digging line, one gnawing at the front while the others push the soil back. It is not quite naked: sensitive whiskers and hairs on the tail help it find its way in the dark. Unusually for a mammal, it cannot hold a steady body temperature, so colonies huddle together and bask in shallow, sun-warmed tunnels instead. Each colony is run by a single breeding queen.