Complicated love life: Study uncovers complex mating behaviour, same-sex pairing in Indian Squid

Kochi: Beneath the waters of the Arabian Sea, the Indian squid has been living a far more complicated love life than scientists once imagined.

A new study by the ICAR-Central Marine Fisheries Research Institute has, for the first time, recorded both heterosexual and homosexual mating behaviour in Indian squid (Uroteuthis duvaucelii), while also uncovering signs of early mating, repeated copulation and the remarkable ability to store sperm.

"The study uncovered fascinating and previously unknown aspects of this squid, including early mating, multiple copulations, and sperm storage," a CMFRI statement said here, quoting the study.

The study, led by Dr Geetha Sasikumar and Dr K K Sajikumar of the Shell Fish Fisheries Division, examined squid samples collected from the Arabian Sea off Kochi.

"Analysis of 232 female squids revealed that 40 percent had sperm carrying structures (spermatangia) attached to their buccal membranes, a fleshy area right around their mouth. This indicates active mating throughout the year with peak activity recorded in October," it said.

Researchers also found spermatangia implanted on the buccal membrane of a male squid, providing the first documented evidence of same-sex sexual behaviour of Indian squid.

Earlier, same-sex mating behaviour had been documented only in deep-sea squids outside Indian waters, where scientists believed the dark environment may have contributed to such behaviour.

Similar behaviour has also been observed in dolphins.

"However, this is the first recorded instance in a coastal squid species," the statement said.

The findings, published in the Journal of Natural History, shed new light on the reproductive biology of one of India's most valuable squid resources, it said.

The study also used statolith analysis to estimate the age of mated squids, finding that mating can begin as early as 98 days after hatching.

Researchers found as many as 385 sperm packets attached around a single female squid's mouth region, suggesting that females may mate multiple times with different males before laying eggs.

According to researchers, this could be linked to dense spawning aggregations where random or opportunistic mating interactions may occur, leading to rapid growth of the squid species.

Researchers believe that understanding the mating system is essential for improving stock assessments and developing effective conservation and fisheries management strategies.

They emphasised the need for further behavioural and physiological studies to fully understand the species' reproductive dynamics.