It's strange, but true: lobsters and crayfish communicate by shooting streams of urine at each other. It sounds disgusting, but it's actually pretty neat. Many animals produce chemical signals for communication. These signals, or pheremones, can carry information about mating readiness or dominance status. Lobsters, crayfish and other crustaceans send these signals packaged in streams of urine.

British researchers studying signalling behavior in crustaceans discovered that crayfish could shoot streams of urine out of pores on the side of their head. Clusters of fan-like appendages near the mouth direct a highly focused stream straight into the faces of others during fights and courtship. The urine contains hormone derivatives that can tell others a lot about the fitness or current state of the shooter-useful information when choosing a mate or when deciding whether to fight or back down.

The researchers studied the role of the chemical signals in fights between pairs of crayfish. They found that "winners" of fights shot more chemical signals than "losers" in fights. But when the urine of crayfish that were normally "winners" was blocked, they started to lose fights. If their urine pores were then unblocked, they became winners once more.

Tune in next time to learn what urine signalling in crustaceans has to do with NASA and odor-tracking robots!