Octopus Mothers Die After Laying Eggs

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Octopus
Courtesy of Sean Gerety (Flickr CC0)

Numerous species of animals die after reproduction. Octopus mothers stop eating when the eggs come close to hatching. After, she moves from the protective crowd over her offspring and turns to self-destruction. She may eat parts of her own arms, throw herself into rocks, or tear her skin.

Discoveries of chemicals that can control the deadly frenzy were made by researchers. Following an octopus laying eggs, her body deals with changes in the creation and use of cholesterol. This makes the creation of steroid hormones rise, which causes self-destruction. The changes might indicate processes that describe generalized longevity in invertebrates, according to Assistant Professor of Biology and Psychology at the University of Washington, Z. Yan Wang.

Wang explained that they are interested in linking them to individual differences and behaviors to how animals show their actions.

Even while Wang was an undergraduate student majoring in English, she was interested in the reproduction of females. As she moved into graduate school to study science, she maintained that interest. She was also shocked by the extraordinary deaths of mother octopuses following laying eggs.

Thoughts Behind Octopus Self-Destruction

The purpose of these behaviors is unknown. Speculations involve the thought that the displays of death would get predators away from the eggs and the possibility of nutrients being released from the body that goes into the water to nurture the eggs. Wang says that it is most likely that death protects the eggs from the older octopuses. The species are cannibals, if the older generation stays in their area they could eat the offspring, Wang explained.

Octopus
Courtesy Elias Levy (Flickr CC0)

A study conducted in 1977 by Jerome Wodinksy, a psychologist with Brandeis University, discovered the mechanism that causes self-destruction is in the optic glands. These glands are located near the eyes of the octopus and are similar to the pituitary gland in people. Wodinsky also discovered that if the glands were damaged, the mother would abandon the eggs, begin consuming food again, and stay alive for approximately four to six months.

However, no one had knowledge of what the gland was doing to contain the flow of self-harm.

Octopus Optic Gland Experiment

Wang explained that she was receptive to performing experiments from the beginning. The experiments consist of getting fluid from the glands and then recognizing the components of the liquid.

Her coworkers and she studied the chemicals made in the glands of two-spot octopuses out of Califonia after laying eggs. A genetic examination of the same octopus displayed that after laying eggs, the genes in the glands that create steroid hormones began working harder. Using the study as a guide, the experts focused on the steroids as well as chemicals related to the production done by the glands in the two-spot species.

They discovered three different chemical changes that happened near the time the mother laid eggs. The first was a spike in progesterone and pregnenolone, which are two chemicals related to reproduction in many species. In people, the hormone progesterone goes up at the time of ovulation and early pregnancy. The second change was the mother octopus started to create more building blocks of cholesterol known as 7-dehydrocholesterol (7-DHC).

People create 7-dehydrocholesterol while making cholesterol as well. However, they do not hold it in their system very long. The chemical is toxic.

Written by Marrissa Kay

Sources:

Live Science: Octopuses torture and eat themselves after mating. Science finally knows why.; by Stephanie Pappas
Independent: Scientists discover why female octopuses self-mutilate to death after laying eggs; by Vishwam Sankaran
The New York Time: The Trigger That Makes an Octopus Mom Self-Destruct

Featured and Top Image Courtesy of Sean Gerety’s Flickr Page – Creative Commons License
Inline Image Courtesy of Elias Levy’s Flickr Page – Creative Commons License

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