By mating, octopuses sign (alas) their death warrant

• Octopuses (or squids) “let themselves die” after reproducing, according to our partner The Conversation.

• Males stop feeding when they have reached their maximum programmed age, while females do so once their eggs have been laid and “protected”.

• This analysis was conducted by Eduardo Almansa Berro and Catalina Perales-Raya, both scientists at the Spanish Institute of Oceanography.

Octopuses reproduce only once in their lifetime.

The common octopus lives only one year, and its life cycle ends after a single reproductive event.

This is not a phenomenon specific to octopuses, but a strategy found in most species of cephalopods, with the sole exception of nautiluses (they reproduce several times during their life, which can last more than 20 years).

Sexual maturation in cephalopods is poorly understood, but it is known to be controlled by hormones produced in a part of the brain called the optic gland.

As in many other animals, this gland integrates information about the animal's growth, body reserves, and environmental factors such as photoperiod and temperature to select the appropriate time to initiate maturation and lay eggs.

The female stops eating and dies after caring for the eggs

However, one characteristic that distinguishes cephalopods from most animals is that this regulation is strongly integrated with the regulation of appetite, so much so that the female stops feeding once the eggs are laid, which inevitably leads to her died from starvation after caring for the brood.

This sort of "programmed suicide" also seems to occur in males, because when they reach their maximum programmed age (usually a year or a year and a half), they also stop feeding.

​Females store spermatophores from multiple males

In cephalopods, courtship is accomplished with the aid of elaborate and visible changes in body coloration and pattern, although in octopuses the foreplay is usually fewer.

Males "pack" sperm into capsules called spermatophores, which are transferred to the female by modification of one of her arms (hectocotylus).

In the common octopus, the hectocotylus of the male forms at the end of the third right arm and allows the spermatophores to be deposited in the oviductal gland of the female, where they will remain stored until the conditions are right for the reproduction.

Observations made in our laboratory have shown that females are able to store sperm for several months before using it to fertilize oocytes and trigger spawning.

Genetic studies have shown that a female can store sperm from multiple males, resulting in multiple paternity broods, although each of them attempts to eliminate spermatophores deposited by previous males.

A numerous and orphan offspring

The care and devotion that the female octopus gives to her brood are other behaviors that are infrequent in the animal kingdom.

The females hang the eggs (several hundred thousand) in clusters inside a safe place.

They usually use a rock hole or hollow of appropriate size and darkness, but may use any spot with similar characteristics, such as some octopus traps common in artisanal fisheries targeting this species.

For several weeks, the female protects the eggs from potential predators, while cleaning them with her suction cups and keeping them airy and moving thanks to the jets of water produced by her siphon.

This process was reproduced in the laboratory without the presence of the female.

Temperature is critical and affects both the duration and the quality of embryonic development.

Temperature increases consistent with climate change have been observed to reduce clutch quality.

Once the embryonic development is complete, thousands of small paralarvae about 2 mm long hatch, equipped with jaws (or beaks) with teeth to hunt, and will travel in the open sea carried by the ocean currents until their final installation. as juveniles.

Towards sustainable production

Rising consumer demand for octopus around the world adds to other threats to wild stocks, such as overfishing, pollution and climate change.

All this has led to the search for alternatives that guarantee sustainable production, including the challenge faced in recent decades: aquaculture production.

The main bottleneck to achieve this has always been the early stages of life.

At these early stages, it is very complex to ensure that the paralarvae receive adequate food and nutrition.

They also have special requirements related to environmental factors such as light.

Following these lines of research, the latest advances made by the Spanish Oceanographic Institute in its centers in Vigo and Tenerife have improved their breeding in captivity.

Achieving their breeding in captivity opens the door to better management of their production for human consumption, both in aquaculture and fisheries, as it also facilitates the study of their biology and ecology.

Our "OCTOPUSES" file

However, significant challenges remain in terms of sustainable production and ensuring animal welfare.

This has always been the objective of the scientific projects of our Octowelf group or of the European CephsInAction network.

Sustainable production and animal welfare must continue to be a priority objective in future research projects.

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This analysis was written by Eduardo Almansa Berro and Catalina Perales-Raya, both scientists at the Spanish Institute of Oceanography.

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Declaration of interests

• Planet

• Video

• The Conversation

• Animals

• Octopus

• Reproduction

• Oceanography

• Sea