The Trigger That Makes an Octopus Mom Self-Destruct

The majority of octopus species live for a year. The deaths of octopus mothers have been a scientific spectacle for a long time.

It's not clear why the self-harm that leads to the death of the octopus mothers happens after they reproduce. A study published Thursday in the journal Current Biology uses the California two-spot octopus as a model to explain the strange behavior.

The author of the study explained that the female of the species goes through three reproductive stages.

The mother handles her eggs with care after she mates. She carefully strings each egg into a strand. She keeps the eggs in her den by blowing water over them to keep them oxygenated and protect them from predators.

She stops eating. She is spending a lot of time away from the eggs. Her eyes become damaged and she loses her color and muscle tone. Many mothers start to hurt themselves. Some rub against the gravel of the seafloor, scarring their skin, while others use their suckers to create lesions along their bodies. They eat their own arms.

Scientists have known for a long time that the reproductive behavior of the octopus is controlled by the animal's two optic glands, which are similar to the pituitary in mammals. The animal's eyes are the location of the optic glands. They don't have anything to do with vision. If both glands are removed, the female abandons her brood, starts eating again, and has an extended life span.

The study describes the chemical pathways that govern reproductive behavior.

Pregnenolone and progesterone are produced by many other animals to support reproduction, which is unsurprising.

One of them makes bile acids that promote the absorption of fats. Many animals have 7-DHC. It has functions in humans, but is toxic and linked with disorders like Smith-Lemli-Opitz syndrome. Dr. Wang and her colleagues believe that 7-DHC may be a factor in triggering self-destructive behavior that leads to death.

A senior scientist at the Marine Biological Laboratory in Woods Hole, Mass., who was not involved in the study, said that the study addresses a longstanding question in the reproduction and programmed deaths of animals.

Dr. Wang said that she was most excited to see the parallel between the two.

She said that the death is very different than the molecule. Human death is seen as a failure of the organs or function.

The system is supposed to be doing this.