Octopus Reproduction: Why They Die After Mating

Octopuses die after mating because of senescence, a self-destructing behavior. Female octopuses die after time the eggs hatch while males die a few months after mating. This behavior is attributed to the optic glands that produce hormones that drive octopuses mad.

The octopus is generally a short-lived animal. Not because they can’t live long lives, but because they self-destruct after mating.

This almost unprecedented feature raises many questions: How do octopuses mate? Can octopuses survive mating? And why do octopuses die after mating?

These and many other questions are answered in this article.

Why Do Octopuses Die After Mating?

Octopuses die after mating because they enter a state called senescence. After mating, both the male and female octopuses produce hormones that trigger this self-destructing life stage.

Octopuses tend to be cannibalistic.^[1] If they do not die after reproduction, it is entirely possible that the parents eat their children.

In order for the babies to survive, the parents must perish.

The reason for the octopuses’ death after mating is probably evolutionary, although there is no definitive academic evidence. 

The life stage following mating is called senescence. It is an extension of the adult life stage and is only triggered by mating. 

Octopuses that do not mate do not enter this life stage.

What is Senescence?

Senescence is a biological term referring to deterioration with age. This process is not unique to octopuses, as it merely describes biological aging. 

Humans also go through senescence, with wrinkles being a prominent characteristic.

Octopus senescence is characterized by different behavior patterns. When they enter this life stage, the following patterns are triggered:^[2]

• Loss of appetite
• Retraction of skin around the eyes
• Self-destruction, tearing chunks out of own body
• Erratic movement
• White, unhealing lesions

Dying after mating only once is called semelparity.^[3]

How Do Octopuses Mate?

Octopus males have a special arm called hectocotylus which is used to transfer a pack of sperm into females. Males attach themselves to females or detach their arm and give it to the female.

Octopuses are solitary and only go out to look after other octopuses when they want to mate. They mate only once in their life and then die after. This is called semelparity.^[4]

Depending on the species, octopuses are sexually mature at a couple of weeks to three years old. Males have a special arm called a hectocotylus. It is used to transfer sperm into females. 

The males of select octopus species detach the arm during mating as they won’t use it again. If the mating is unsuccessful, the arm will grow back.

Here is the process of octopus mating:^[5]

1. Octopus reaches sexual maturity (anywhere between a few months to three years).
2. Goes out to look for a partner.
3. When the male finds a female, it chases it.
4. Female fends off the male at first but accepts it eventually.
5. The male attaches the hectocotylus to/detaches the hectocotylus and gives it to the female.
6. Sperm is released into the female’s mantle cavity.
7. After the female is fertilized, the two parties part ways.

How Do Octopuses Give Birth?

Female octopuses lay eggs. They search for sheltered places, such as crevices or the underside of rocks to lay the eggs. Depending on the species, females lay up to 140,000 eggs the size of rice grains.

Females lay tens of thousands of eggs because of the survival rate of the offspring. From one batch of hatchlings, only one percent survive the larval stage.

Egg Count	Up to 140,000
Where Are The Eggs Laid?	Seaweed, rocky dens, small crevices, sheltered spaces, the underside of rocks
Egg Size	0.1-0.3 inches (a grain of rice)
Egg Appearance	Elongated, small capsules, milky-white to transparent, attached to surface
Egg Hatching Time	2–10 months, depending on species and water temperature (eggs in colder water hatch later)
Female’s behavior during egg laying	Frantic search for egg-laying space, weave eggs together, clean them and guard them, stop feeding, die soon after the eggs hatch.
Male’s behavior during egg laying	Separate from female, behave erratically, endangering themselves, and die a few weeks to a few months later after mating.

Can Octopuses Survive Mating?

No, octopuses cannot survive mating. Their death is inevitable. This might be an evolutionary block for octopuses, so they do not eat their children.

Senescence is irreversible and unavoidable. Once the chemicals in the optic glands start to overproduce, octopuses are sure to die soon.

It’s important to note that senescence is not a disease. It is a natural conclusion of the octopus’ life. 

The reason why this life stage appeared in octopuses is probably due to their cannibalistic nature. Octopuses are known to eat each other. Even hatchlings in the larval stage consume one another, therefore they are cannibalistic. 

If females survives for long after the eggs hatch, it’s possible that they would eat their children. The molecules produced during senescence also prevent the parents from consuming the eggs.

Do Female Octopuses Eat Males?

Yes, some female octopuses eat males. This is another characteristic of senescence. Females eat males to survive longer and to prevent males from eating the offspring.

Although males leave females after mating (and lose their appetite), some females kill their mates. They often use their arms to strangle them and eat them afterward.^[8]

Octopus males die a few months after mating anyway, but females killing them might be another behavior of senescence. 

Some females kill and eat their mates for the following reasons:

• To prevent males from eating the eggs.
• To sustain themselves for the duration of egg-brooding.
• Due to the frenzied state females enter after mating, they perceive males as a threat.

Conclusion

Octopuses die after mating when they enter a life stage called senescence. It is characterized by self-mutilation, lack of appetite, and erratic behavior. Males die a few months after mating, while females die around when the eggs hatch. 

Senescence is triggered by an overproduction of molecules in the optic glands. This might be an evolutionary preservation mechanism, as octopuses might eat their offspring if it weren’t for senescence killing them.