Scientists astounded after finding out why female octopuses self-destruct after laying eggs

Time and again, nature proves to be full of bizarre adaptations that humans can’t fully comprehend. Take octopuses, for instance; these marine creatures possess a peculiar metabolism that could be described as theatrical. From throwing ink or debris at their opponents to performing different tasks with each arm, octopuses are fascinating creatures to learn about. One such strange characteristic that has often perplexed the scientific world is the self-destructing nature of female octopuses after they have reproduced. In June 2022, researchers identified the intriguing reason why octopus mothers mutilate themselves after laying eggs and the results are published in Current Biology. 

It turns out these cephalopods are destined to be orphans shortly after their birth. Yes, once a female octopus lays her eggs, she enters a stage of self-neglect. She stops eating, and her self-mutilating behaviors can escalate to tearing off her skin and biting the tips of her tentacles. Sadly, when her offspring hatch, she is no more and just months later, the cephalopod father will meet a similar end. It is terrifying, but true! For ages, this brief and somber lifecycle of the octopuses has intrigued scientists. However, in 1944, researchers suggested that the act of mating triggers a molecular "self-destruct" mechanism in these cephalopods. There wasn't much evidence backing this hypothesis until recently.

A research team led by Z. Yan Wang, a professor of psychology and biology at the University of Washington, finally found a plausible reason. Their study detected changes in various biochemical pathways related to cholesterol metabolism and hormone production in female octopuses after mating, per Science Alert. "We know cholesterol is important from a dietary perspective, and within different signaling systems in the body too. It's involved in everything from the flexibility of cell membranes to the production of stress hormones, but it was a big surprise to see it play a part in this life cycle process as well," Dr. Wang told EurekAlert. They found that higher levels of cholesterol precursors might lead to behavioral impacts like self-injury and ceasing to eat, even in humans. 

The same has happened with these cephalopods. In 1977, one study attributed these predestined octopus deaths to the presence of an optic gland that functions similarly to the human pituitary gland, reported Science. Located between the eyes, the optic gland is involved in sexual maturation and aging. In a remarkable discovery, when it is removed from a female octopus, she can live several months longer after laying her eggs. Now, years later, Wang and her team analyzed the direct investigations of the molecules secreted by the optic gland in both mated and unmated females. Their findings revealed that after mating, the optic gland indeed releases elevated levels of sex hormones, insulin-like hormones and cholesterol precursors that lead to self-mutilation in female octopuses after laying eggs.

Looking forward, Wang and her colleagues plan to delve deeper into the biochemical processes involved so that additional molecules responsible for the cephalopods' programmed death can be found. "What's striking is that [octopuses] go through this progression of changes where they seem to go crazy right before they die," Clifton Ragsdale, a neurobiologist from the University of Chicago and a part of the research team, told the media channel. "The important parallel here is that what we see in humans, as well as in octopuses, is that high levels of 7-DHC are associated with lethality and toxicity. And that, to me, is really interesting, just because of how evolutionarily divergent these two animals are," Dr. Wang told New Scientist.