Evolutionary advantage of death at childbirth for octopi?

I’ve been reading on Octopi and apparently the females starve themselves while taking care of her eggs, dying at childbirth. Why do this? Why not live for another round of spreading her genes?

Also, apparently males only live for a few months after hatching their young, but I don’t know the mechanism of their death.

There has to be an evolutionary advantage, otherwise it would not be existent on a species level. I think the female who starve and die at childbirth has a higher rate of spreading its genes than those who do not do so. She put all her energy into spreading her genes in one go, giving an advantage over those who do not. And rememebr living means surviving, if one lay 4 eggs and shortly after the birth she got eaten by predator, it would not be as good as investing all energy and lay 8 eggs and die, just an example.

Investing all of the resources of the adult in the production of the next generation is not uncommon in nature. Annual plants do it, salmon do it, some spiders do it.

It means that the parent can divert more effort and energy to the survival of the offspring.

Although once established, it can also just be a founder effect that a species gets stuck with.

To me it seems a lot more efficient to do it more than once. When being born the octopuses, depending on the species, have to wait years before reproducing and then dieing. If adult octopuses could procreate multiple times then the species would spread a lot faster, as well as the genes of the parents.

The “more efficient to devote all of its energy to the survival of its offspring” is too vague to me. Why do octopuses need to do that and in what form (of energy) do the eggs need “all of the energy of their parents”?

I can think of a few possibilities:

  1. Octopus eggs are too tasty for other sea animals, so the octopus has to devote all her time to defending them. I don’t buy this, the male could get the female food or the octopuses could only leave for a little while to get food, while hiding their eggs, which octopuses are good at becuse even huge ones can squeeze through extremely tiny holes. Heck, I know that octopi are solitary creatures but it seems easier to evolve some kind of rotation where the octopus goes to look for the food and the other protects the eggs and vice versa.
  2. Some natural physical limitations in the biology of octopi that would cause them to not be able to live much longer anyway, thus it is more efficient to just focus the last of their life on taking care of their eggs full time.

To Griffon’s argument: so why would it be more advantageous to them to reproduce only once with a little smaller risk, than reproduce 10 times more offspring over time with a little more risk? The argument does not satisfy me. There’s more to it.

Any more ideas? (or facts)

Do the young eat the parents?

And, yes, I am serious–seems like a good available source of protein.

I don’t think so. I know that some animals do that, but I didn’t come across that while reading about them, and I couldn’t find anything about that being the case.

One thing to always bear in mind for this sort of question is: if this wasn’t a viable strategy for the octopus, we wouldn’t have any of that species. Evolution doesn’t always find the optimal solution to any problem - just solutions that happen to work well enough.

But in cases where the offspring (be they eggs, seeds, larvae, etc) are not nurtured by the parents, any energy and resources reserved for the survival of the parents is energy/resource not available to the next generation - in practice (and all other variables being equal) this means that if the parent must survive, there will probably be fewer offspring, or they will be weaker.

Once a species has developed that reproductive strategy, all of its descendants will have a tendency to follow suit - and the strategy can become so embedded that even when some other way would be theoretically better, there’s no way to get to there from here.
Imagine you’re a mountaineer; climbing toward the peak of the nearest mountain probably won’t get you to the peak of the tallest mountain in the world, unless you descend and try another one - and in many cases, descending would mean starting over from scratch - this is the founder effect - you can only reach the summit of the mountain you’re actually climbing.

Doesn’t matter if it sounds efficient to you or not. You’re not God you are not supposed to know everything. The fact that this phenomemon exists on a species level means it is a working model. Whether it is efficient is irrevalent and efficiency itself is vague if you don’t put it into a context. For instance humans are not efficient when it comes to victamin C but this does not make humans inefficient, it all depends on what variable or circumstances you are looking at. The octopus’s model is working model that is all that matters. If some other species of octopus have the multiple-birth model and they out-compete the octopus with single-birth model then you can say the latter are inefficient when it comes to spreading of their genes.

Thanks for all your answers, I am too much in the habit of assuming that evolution always finds the perfect solutions, but then life would probably be a lot less varied on Earth.

Octopi are extremely intelligent and resourceful and even process feelings such as love and empathy which are normaly traits of mammals. Very possibly they would be far too successful if they lived past one breeding and this very well might be the one weak link needed to ensure the survival of the species.

Evolution is never about the survival of species. It’s not even about individuals. It’s all about the spread of genes. You still understand evolution based on Charles Darwin, but his ideas are far outdated. For modern evolution theory you need to look up Richard Dawkins.

There is no “perfect solution”, only “solutions” (I don’t like this word because it implies intent/purpose) that works. Evolution has no meaning, intent, or purpose , it is nothing but a natural phenomenon.

Not true. Commonly believed, but not true. All something has to be is not significantly disadvantageous, which is a whole 'nother thing.

Oh, and it’s octopuses or octopods for the plural.

For something as major as dying after reproducing, it does imply an advantage. It’s not as the same as whether a seagull having red feet or blue feet.


This Wiki articlediscusses these things.

No, it doesn’t.

They are very efficient predators. The mother’s death may well leave more food in the environment for the offspring to survive on, because they will not be competing with a larger, wiser, more efficient predator. Just one possibility among many…

Is there a way to prevent a female octopus death? For instance, if it’s isolated from its eggs, either by a scientist or because the eggs are eaten by a predator (I’m assuming it’s conceivable even with the mother guarding them), will it still starve to death?

I don’t know about the females, but I was at the Seattle aquarium and saw the male giant octopus there. It was lethargic and not eating, and the experts there explained that it had mated recently and would die within a few months.

It sounds like the not-eating is a behavioral issue rather than a symptom of “old age” or something more tangible. In any event, the male isn’t involved in guarding the eggs with this species, so it wasn’t a result of that either.