The silver ant -- Cataglyphis bombycina -- is the undertaker of the Sahara desert -- a role it has been forced to adopt because of its own body limitations and because of a small lurking, desert lizard that loves to gobble them alive.

Rudiger Wehner of Zurich University began a study of these ants wanting to know how they cope with high heat and why they confine themselves to brief bursts of midday activity. He reports (Nature, vol 357 no. 6379) that silver ants confine themselves to their relatively cool burrows until the temperature at ant height (4 mm off the ground) reaches 45-47oC, by when all other arthropods invertebrate animals with external skeletons, including desert ants, have either found shelter or perished.

Scout ants emerge from burrows early in the morning and monitor the rising temperature. When the temperature is just right, they trigger a dramatic burst of activity, in which a few hundred ants pour into the open and scurry about for three or four minutes. They forage feverishly, gathering corpses of woodlice, spiders and insects that have succumbed to the heat and then scoot back to their burrows before the temperature at ant height reaches 55