Terminal species

[Koshmar]

Cephs are what got me into saltwater aquariums in the first place, specifically cuttlefish. Ever since visiting forums and looking up information on them, I have always wondered why they are terminal breeders (why they die after giving birth or mating). I would like an evolutionary and biological reason but I just can't find an answer. Even at the public aquarium I volunteer at, the keeper that takes care of the GPO does'nt have an answer to this elusive question. Is it because they are such efficient predators that if they lived after mating they would over populate the ocean or is it simply that the energy required to create such an advanced organism is too much for the parents to handle?

[Animal Mother]

Good question.

Generally it does take everything the parent has to produce and care for the eggs. The females lay eggs at the peak of their health. It's just the way nature built them. I think of it like this. When food is most abundant is the most ideal time to have babies.

Hopefully someone with some real biology education will chime in.

[philter4]

It has been shown that cephalopods that do not breed survive longer then a year, some if they don't breed up to 3 years. There is also some research to suggest that if they would feed they could survive longer. In some studies, food was presented to the female while she was guarding eggs, if she ate she survived several months after the eggs hatched instead of weeks.

IMO it is the energy required to reproduce that causes the death of the animals, and it isn't just cephalopods, there are several groups of animals that expend so much energy that they die, salmon for instance.

[a7oneal]

I have a background in ecology, and I was intriqued by the question without even knowing a heck of a lot about octopuses.

Octopuses are classic r-selected strategists when it comes to reproduction. They have high mortality of offspring and often live in environments of varying stability.

Preliminary searching unearthed an article by Wodinsky (1977) that states that secretions from the optic gland may result in the death of octopuses, and that removal of the glands resulted in increased feeding, longer life spans, and lack of brooding. The question posed here was why evolutionarily... and this article suggests it's a population control mechanism.

I would propose this with a caveat, namely that this article is 30 years old, and I'd want to see if the theory has changed with more recent literature (for example, I found another one by Anderson et al. from 2002, that I do not currently have access to, which discusses ecological implications). I would be curious if this increase in hormone production is triggered by physiological changes in the octopus due to decreased feeding... in essence, induce death before starvation.

[Gonodactylus]

I won't tell you the answer(s) because I (and no one else I know of) have yet to put together a complete explanation. I will throw out two bits of information with respect to octopus to add into the equation.

1. Males seem to die at about the same age and size as females. We don't yet know how sexual activity affects this.

2. Some species of octopus such as Octopus chierchiae are not semelparous and lay several clutches of eggs over several months.

Roy