New research from Japan reveals that the hatching date of Japanese spear squid determines their future mating tactics. Squid hatched early in the breeding season become consorts (fighters) who fight off rivals and guard females, while those hatched later become sneakers (sneaks) who surreptitiously deposit sperm near the eggs. This phenomenon, known as the birthdate hypothesis, has previously only been observed in humans and suggests that male mating behaviors are locked in from birth. The study also highlights the potential influence of environmental factors on mating tactics, as squid are sensitive to water temperature and extreme events could impact their growth and reproductive strategies.
