Why the male dies after mating?

[DWhatley]

This thread had started me wondering how many animals with the level of intelligence of the octopus naturally lives for such a short time. Does any one know of a good search engine for scientific research? The most popular produce more revenue sites than informational any more.

 

[monty]

This thread had started me wondering how many animals with the level of intelligence of the octopus naturally lives for such a short time. Does any one know of a good search engine for scientific research? The most popular produce more revenue sites than informational any more.

scholar.google.com is one of the better hardcore academic ones, but frequently points you at papers that you (or your school) have to have a paid subscription to read. Cephbase has a lot of articles on cephs specificially, too. There are a number that universities can subscribe to, but I'm not sure which ones are available to the public. There's not much gray area between "completely pop culture web" and "only academic, peer-reviewed papers," though, so I frequently find I have to look through all the junk in a broad google search to find things that are intelligent yet comprehensible to people without years of learning obscure terminology.

 

[DWhatley]

Thanks, I "bookmarked" it. and did a quick search to see what kind of references it gave. I am glad Google is experimenting this way but their revenue generation stream may not get it past beta. I will be glad when online books are mainstream. I don't mind paying for information I want but I do mind paying just to see if an article contains information I need.

 

[main_board]

Both male and female Salmon die after spawning. Is there some kind of evolutionary advantage to this? To other animals it means more food but to the offspring?

Monty touched on this. To spawn, salmon migrate to rivers and streams that aren't exactly rich in food for the fry. By dying, the adults provide an initial food resource for the fry (and the surronding community). I don't mean to say that the fry hatch and start to pick at the dead bodies of their parents (I think hatching takes too long anyways), but I mean the decomposing salmon provide the starting point of a food web that will produce suitable food for the fry.

Now in octopus, as it has been stated, there is a lot of grey area. I remember watching a documentary on GPO where the female denned up, failed to eat for months, and as a result died just around the hatching time for her brood. It was claimed that her death also provided an early food source for her brood, I'm not sure if directly or indirectly (as in the salmon example). Not all octopus act this way.

Clearly, there are advantages to dying as an adult.

The reason (or so I have read once) female octopus' die after laying eggs is that they generally don't eat while brooding. As a result, to sustain them selves (in some cases over months!) their body systematically digests itself, starting at the least important tissues. By the time the brood hatches, the female is beyond recuperation.

Cheers!

 

[DHyslop]

The reason (or so I have read once) female octopus' die after laying eggs is that they generally don't eat while brooding. As a result, to sustain them selves (in some cases over months!) their body systematically digests itself, starting at the least important tissues. By the time the brood hatches, the female is beyond recuperation.

Occasionally--in O. bimaculoides at least--the brooding female can even resort to eating a festoon of her own eggs. I suppose its worth it if it keeps her alive until the rest of the eggs hatch without having to leave to hunt.

Dan

 

[xarvh]

Thanks a lot to Steve O'Shea for his explanation on spermatophores.
It cleared out a lot of confusion.

[cut]
In blue-rings, we have mated males daily to several different females and they certainly did not drop dead. WIth more controlled experiements, we hope to clarify this a bit more.

Roy

This is what i wanted to read: males do not die as result of mating.
The better answer i found so far, as Nancy pointed out, is that octopuses just die of senescence.
Their lifespan after maturity is very short, and so they apper to die "just after mating".
This implies that they would die regardless of mating, given the same conditions, and that mating triggers no special "program".
Does this make sense?

 

[cthulhu77]

Yes, it is much more likely that the males have reached the end of their lifespan with the advent of sexual maturity, at least measured in days and weeks, not months, until the end.
Different animal species have different reproduction strategies, some reproduce quickly, and die quickly to make room for their own genetic offspring...while others take a long time to mature and produce their young.
In this situation, it is normal for the faster reproducing species to become subdominant in any particular arena, there are certainly more squid being born every year than Orange Roughy, correct ? This may lead to the phasing out of the slower reproducing animals, and replacement by the swifter...which, in turn, then evolve into slower and longer life cycles, only to be overturned in their course by another, new animal species.
So, perhaps in time, we will see octopus that live out a long life span, and have a limited reproduction cycle, although this is maybe a tad unlikely, as they have proved to be so successful with the short term lifespan that has worked out so well for them. The one nice thing would be, with the longer lifespan, they could enlarge their area of occupation to include zones that have less food availability, and without the need to feed almost constantly to maintain the fast lifestyle, they would be able to even live in a freshwater environment.
Just think of the savings in sea salt ! (yeah, I know...millions of years, etc, but I can wish, can't I?)
Greg

 

[Neogonodactylus]

Just to be clear, I didn't say that mating has no effect on male senescence. It may. We just don't have the data to say if or how much mating activity or even exposure to females accelerates senescence. Hopefully in a few months we can provide more information on this.

Roy

 

[xarvh]

Just to be clear, I didn't say that mating has no effect on male senescence. It may. We just don't have the data to say if or how much mating activity or even exposure to females accelerates senescence. Hopefully in a few months we can provide more information on this.

Roy

Indeed, but now the role of mating seems to lose importance respect to age.
Most doubts where cleared knowing that the male can actually mate more than once.

Please keep me updated with your work!
On that and on the mantis too! (I just finished my first amatorial dissection)
Is there any place you're going to publish those results?