Graduate School of Frontier Sciences, The University of Tokyo Department of
Integrated Biosciences

Why do males and females show great differences in morphology and behavior? Why do individuals show great variations even in the same sex in the same species? How do environmental conditions affect such intraspecific variations? To answer those questions, I am studying sexual selection in cephalopods. Why cephalopods? To be honest, I was not especially a big fan of squids and octopuses. But I found that they are very interesting organisms to study sexual selection. They have highly developed eyes, brains, and cognitive abilities, and they communicate with each other with visual signals such as body color patterns and postures which they can change instantaneously. Males in cephalopods transfer sperm by hand with capsules filled with sperm to the female's body, and the females store the sperm until spawning but discard it after copulation in some cases. In addition, cephalopod life history traits, such as growth and maturation, vary greatly depending on environmental conditions. These characteristics make cephalopods a good model for studying pre-copulatory sexual selection for mating opportunities and post-copulatory sexual selection for fertilization opportunities.