Pre-senescence aging

Discussion in 'Physiology and Biology' started by Decay, Nov 19, 2008.

  1. Decay

    Decay Blue Ring Registered

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    this might be a dumb question, but i have recently been wondering if octopuses age in a similar way to humans. do they experience a decline in strength, coordination and cognition or do they simply remain in their "prime" until senescence kicks in?

    should someone feed an older octopus smaller prey items and give it less complex puzzles to solve to avoid stressing it and causing overexertion?
     
  2. Jean

    Jean Colossal Squid Supporter

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    In my experience (at least with NZ species) there doesn't seem to be a huge decline, they seem to slow up on feeding and get a little lethargic then suddenly they're senescent (in males), in females the first sign is usually egg laying!.

    J
     
  3. gjbarord

    gjbarord Sepia elegans Staff Member Moderator

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    In animals where so much energy is placed into reproduction and subsequent egg-laying, the decline seems to differ by sex. The females are brooding eggs for months and tend to decline at a much slower pace. The males seem to start their decline, at least mentally, soon after reproduction and it seems to be a fast change.

    Some octopus will decline sooner than others, just as some humans decline quicker than others.

    Greg
     
  4. monty

    monty Colossal Squid Staff Member Supporter

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    Going on the thin ice of hypotheticals, since cephs only reproduce once, and don't care for their offspring after hatching, it would seem that they have a lot less benefit from staying healthy after reproducing. Not that they have evolutionary pressure to die immediately, but they have a lot less pressure to survive than animals that might reproduce again, or that, like mammals, have to raise their offspring until they can take care of themselves. These sorts of discussions are always more complicated than they seem, though: before reproduction, there's a lot of survival and fitness needs, and there's not a lot of incentive to "switch off" all that, either, particularly since the young migrate away from the parents, so the parent isn't taking up resources the offspring need. There might be incentive for the female to get as fit as possible, then switch off and only take care of the eggs, but it's harder to see that in the males. On the other hand, maybe the males just have inherited the this aspect of the females' physiology, since they don't have reason not to, just like men having nipples...

    Going a bit far afield of the original topic: we don't even know, AFAICT, what genetic or epigenetic or environmental control causes an octopus to be male or female; they don't have analogous X and Y sex chromosomes that anyone has discovered so far, and many of their gastropod relatives are hermaphroditic. Steve O pointed me at an article on a South African squid species where a few individuals show both male and female traits, so there's some opportunity in at least one ceph species for gender ambiguity.

    Since it's been found that the octopus optic gland influences the onset of sexual maturity, I have to wonder if there is or was some evolutionary advantage to having the animals recognize favorable conditions for reproduction, and then flip the switch to go into full-on breeding mode. The mass spawning of some squids seems to be an example of this, but it's less clear why octopuses might do it; perhaps it's carryover from much older cephalopods? Of course, nautlius and cuttlefish don't seem to do anything like this, and lay eggs over a long period, so it's not all cephs. Does anyone know anything about Vampyroteuthis or Cirrate octo reproduction? Or Spirula?
     
  5. cuttlegirl

    cuttlegirl Colossal Squid Supporter Registered

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    My males lived much longer than my females and I think Thales has had some of the same results with some of his batches. So cuttlefish (or at least S. bandensis may not follow this trend. The more we learn about cephs, the less they seem to follow the long held belief of mate once, lay eggs and die...
     
  6. nanoteuthis

    nanoteuthis Larger Pacific Striped Octopus Supporter

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    Hey, that is the same as in humans!

    :mrgreen:
     
  7. sorseress

    sorseress Colossal Squid Supporter

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    Hee Hee Hee!:sagrin:
     
  8. lurker

    lurker Pygmy Octopus Registered

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    Actually, they would have pressure to off themselves... They'd be competing for resources with their offspring. :baby::goodbye: It is essentially the same everywhere. We humans die off after we pass breeding age, too. :sink:

    I read your other thread about the optic gland... I'd be expect it would greatly increase longevity. (Sounds like a Masters/Phd project to me, except that it would take too long to yield results) .... and I'd also be interested to see if older octopi are smarter.
     
  9. gjbarord

    gjbarord Sepia elegans Staff Member Moderator

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    Perhaps I need to put some more thought into having kids. Yikes...:tomato:

    My thoughts on longevity are in terms of wild animals. This discussion seems simililar to one in the past. I would think that senescent males would be eaten before they died of anything else. Animals in captivity have it all so there may be no difference in longevity between sexes. You might say they are spoiled... :roflmao:

    Greg
     

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