SHELTER SHARING AND CHEMICAL COURTSHIP SIGNALS IN THE LOBSTER HOMARUS-AMERICANUS

In a 3.7-m Y-maze flume study of social odor-mediated behavior of matu re lobsters (Homarus americanus), females preferred male- but not fema le-occupied shelters over empty shelters: they detected them from a di stance and spent much time trying to enter. Males did not show distant detection and preference for female shelters but did spend much time trying to enter female but not male shelters once nearby. Sheltered re sident males showed strong aggression toward visiting males but only m ild aggression to visiting females; intermolt and premolt females coul d enter resident male shelters, cohabit for at least 7 h, receive mati ng attempts, and sometimes mate. Premolt females or females with sperm plugs resisted mating attempts. Visiting females released more than f our times and males more than seven times as much urine during a shelt er approach compared with an equal time in isolation. Females with or without urine release entered male-occupied shelters successfully, but mating attempts rarely occurred when female urine release was blocked . Female urine block resulted in greatly increased resident male aggre ssion toward her, reaching the same levels elicited by visiting males with or without urine block. The results show that female urine signal s reduce male aggression and facilitate mating.