This squid’s birth month determines how it mates forever. Do you still laugh at the stars?

Some squid appear destined to become stealthy or aggressive mating partners, depending on the time of year they were born.

If you have a scientific mind, you may not care much about horoscopes and their predictions about your future, even if they are based on the positions of the stars and planets in the sky on the night you were born.

And probably, you are absolutely right.

However, according to a new study, some squid appear destined to become mating partners. “stealth” or “fighter”depending on the time of year they were born.

The results of the study were presented in an article published this Wednesday in the journal Proceedings of the Royal Society B Biological Sciences.

During the study, the marine biologist Shota Hosonofrom the University of Tokyo, and his colleagues, studied Japanese squid (Heterololigo bleekeri) and discovered that the Male reproductive tactics depend on the month in which they are born.

The squid that hatched at the start of the breeding season, between early April and mid-July, had grown comparatively larger by the time of mating and have become “fighters”: squids that fight rivals to impregnate a female and then guard her while she lays her eggs.

The squid that hatched laterbetween early June and mid-August, were typically smaller and became “stealthy” – secretly depositing his sperm outside a female, close to where she lays her eggs, in the hope of fertilizing them.

Those that hatched in early July were equally likely to be “stealth” or “fighter.”

This phenomenon is called relative age effect and can be clearly seen in the way the children born at the beginning of the year have a better chance of becoming professional athletes than others in their age group because they have more time to develop before selection.

However, prior to this squid study, this “date of birth hypothesis“, as it is also known among biologists, had only been tested on several species of teleost fish and in no other taxonomic group in the animal kingdom other than humans.

“Typically, large males adopt the tactic of competing with mating rivals, while small males adopt the tactic of stealing fertilization opportunities from large males”, explain Hosono and colleagues in the article, after studying 201 male squid and 68 mature females.

This is the first time evidence has been found of the “birthdate hypothesis” in aquatic invertebrates, suggesting that males of H. bleekeri They are locked into mating behaviors from birth.

Even when male squid born earlier in the season failed to grow as expected, did not go against the anniversary trend and opted for the stealth approach; They postponed mating completely and continued to grow until they were big enough to be a consort.

“Our results showed that the hatching date determines the entire life trajectory of this species”, he states. Yoko Iwataa marine ecologist at the University of Tokyo, in a statement published on the university’s website.

Furthermore, these mating tactics are not simply inherited from the paternal line, argue Hosono, Iwata and their colleagues.

“Female squid store sperm from fighting and elusive males throughout the breeding season and use a mixture of sperm from both sources to fertilize their eggs during a spawning event,” the researchers explain.

A genetic variation resulting from reproductive tactics Alternatives can influence the mating behaviors of animals, including birds and damselflies, although documented examples are rare.

But Hosono and colleagues’ findings suggest that males’ mating tactics H. bleekeri are probably determined by a mixture intoxicating combination of physical, biological and environmental factors at birth.

In beetles, for examplethe availability of food is a determining factor in the physical traits linked to sexual success later in life.

This seasonality also occurs in humans: the season in which we are born leaves its mark on our DNA, affecting the chances of us suffering from allergies, for example.

“The difference in hatching date means that the squid experience environmental conditions different early in lifewhich can influence the growth trajectory”, says Iwata.

The squid are very sensitive to environmental conditionsparticularly water temperature. If an extreme event, such as a marine heatwave, occurred during the hatching season, it could affect the size of the squid’s mature body and its subsequent mating tactic.

However, the growth rate in early life It wasn’t much different. between fighting and stealth squids, despite having grown in different seasons.

Therefore, say the study authors, further study is needed to unravel how environmental factors can affect squid mating behaviors.

However, we can rest assured. The peculiar behavior of squids is a question of sizenot from the influence of the stars.