The stingless jataí bee lives in a vicious world where marauding robber bees steal its food and plunder its hive. For protection, Jataí worker bees have evolved a specialized variant: the bouncer bee, a burly guardian with massive legs and a surprisingly small head.
Typically, bees fit into three physically distinct castes. The queen lays eggs; male drones mate with the queen; and female workers guard the nest, collect food, and construct honeycomb. Scientists rarely observed physical differences among workers and widely assumed their size was uniform.
But while studying Jataí in São Paulo, entomologist Cristiano Menezes noticed that the females at the hive entrance looked larger than other workers. Measurements from 12 bee colonies confirmed that. Some Jataí, specialized for guard duty [$], are 30 percent heavier, with legs about 40 percent larger than those of foragers. Their heads are oddly disproportionate, only 25 percent larger than foragers’ noggins.
Guarding is a grisly job made necessary by food raids from Lestrimelitta limao, a strong-jawed robber bee. Bouncers chomp down hard on the base of the enemy’s wing. But intruders can twist around and decapitate a guard with a powerful bite. “You’ll often see a robber bee walking, and on each wing is a separate Jataí mandible,” says entomologist Christoph Grueter, who published the work with Menezes. Even when killed, the bouncers prevail: Robbers with Jataí heads on their wings can no longer fly.