Releasing a steady stream of urine to attract a mate and then fighting off anyone who still dares to approach you doesn’t seem like a great idea for getting sex. But this bizarre strategy is all part of the mating ritual of the signal crayfish. A female’s urine, strange as it sounds, is a powerful aphrodisiac to a male.
Fiona Berry and Thomas Breithaupt studied these courtship chemicals by organising blind speed-dates between male and female crayfish, whose eyes had been covered with tape. They also injected a fluorescent dye into the animals’ bodies, which accumulated in their bladders. Every time they urinated, a plume of green dispersed through the water.
