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CHALLENGE

tonmo

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And I wonder how easily an Architeuthis can recover from having one of their two tentacle clubs bitten off, or would this be likely to be a fatal injury? i.e., does Architeuthis entirely rely on its clubs for feeding? Do they "grow back" as in an octopus arm?

One more question -- can someone summarize here what we *do* know about the Architeuthis mating procedure? As I recall, we have very little knowledge on this.
 

Steve O'Shea

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Howdo Tony. Can't keep a secret from you ay! There's actually a paper on this very thing:

Aldrich, F.A.; Aldrich, M.M. 1968. On regeneration of the tentacular arm of the giant squid Architeuthis dux Steenstrup (Decapoda: Architeuthidae). Canadian Journal of Zoology, 46: 845-847.

The loss of at least part of the tentacle club is not likely to be fatal; they can regenerate.

Phil, you can't ask questions like that online! They're not appropriate :wink: :lol: Sure it's possible; we think it likely in fact.
Cheers
O
 

Tintenfisch

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Well, the gut contents MS is out of our hands for the moment. Thought you guys might like to see a clearer representation of the fragments and Mystery Rings we found in there, so here are our illustrations...

 

tonmo

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Thanks T!

Also, FYI for everyone: a few posts back I asked for a summary of what we know about Architeuthis reproduction... Dr. O'Shea has provided a fascinating summary complete with anatomical photos which I will be posting soon; tonight, I hope... Tremendous thanks to Steve and T for their efforts here!
 
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Amazing article! It appears that Archis have reproduction habits that rival the Surinam Toad's in weirdness. What I'm not clear on (due to my own non-professional status rather than any lack of clarity in the paper) is whether this indicates conclusively that Archis are terminal breeders. Just wondering....

:twocents:
My Two Gold Doubloons
 

Steve O'Shea

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Howdo Tani.

I'd say that they did spawn several times within any breeding season, but that they do not survive that season. I had initially thought that several hundred thousand eggs might be contained within a single gelatinous egg mass (based on the phenomenal number of eggs, several hundreds of thousands, in the mature female's ovary), although I now have reason to believe the number is significantly less (and that she may release a number of these gelatinous egg masses with somewhere in the order of thousands of eggs contained within them instead). That's slightly off the topic though.

A statolith (see Fig 1 attached here) is a tiny bone located within the cartilage of the head (inside a chamber called the statocyst). In a mature Architeuthis of mantle length ~ 2 m this bone is about 2-3 mm in greatest dimension (i.e. it is very tiny). Thin-section light-microscopic analysis of the statolith's structure (counts of rings) has proven a good tool for aging squid. When the number of rings in the statolith of mature Architeuthis are counted we see ~ 470 rings (see Fig. 2 attached here; don't worry about the letters on the image). Each ring is supposed to be deposited on a daily basis (this has been validated for a number of shallow- and warm-water species of squid, but not for deep-sea cold-water species; there is a lot of debate). If an Architeuthis was to spawn off West Coast South Island (Hokitika region) in the months of July and August, then live a further six months, during which time it migrated to the East Coast of South Island (off Banks Peninsula) to spawn again, I would expect there to be a further ~ 180 rings deposited on the statolith (when sectioned and counted). I don't see this; the ages of both East and West Coast specimens are comparable.

This suggests that the animals are either terminal spawners, or that they migrate outside of the New Zealand region once they have spawned, either to die OR to live longer and return to spawn another season. The latter is unlikely, as again you do not get statolith ring counts of ~ 550 rings (and you do not get considerably larger females, which you would expect if they lived for several seasons). The former also seems unlikely, because if something is exhausted why waste residual energy to migrate away only to die.

It is all indirect evidence, but it certainly suggests that the animals are terminal spawners. Moreover, the evidence supports the existence of two spatially and temporally separate populations of Architeuthis in New Zealand waters (however, the DNA evidence ... more to follow soon .... does not support the existence of two separate species).

What has always confused me, if Architeuthis is so common in New Zealand waters, is why more strandings are not found (if they are in fact terminal spawners). I am aware of only two strandings in the past 8 years (my how time flys), and both specimens looked as if they had been discarded by trawlers at sea (as opposed to natural mortality post spawning).

There are so many interesting questions to address yet when it comes to this animal!!



 
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Again, fascinating. Do you suppose this implies that the female mates with more than one male during that season, or conversely, that some of the spermatophores from a single mate are retained and "portioned out" over the release of several egg-spheres?

I don't know if I expressed that clearly, but hopefully you know what I mean -- e.g., I've read that some female sharks appear to give birth parthenogenetically (sp?), when in fact they are able to retain sperm from a single mating for extended periods of time, and to release fertilized eggs at intervals depending upon environmental conditions.

From the convoluted thinking
and awkward vocabulary of Tani :bugout:
 

Jean

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Hi Tani,

Several shallow water squids store sperm. N. sloanii store it in the buccal region (round the mouth, a most awkward place for fertilisation, I would have thought!!). I have a vague memory of reading something somewhere that suggested that female Archis had sperm stored in the arms?????? The suggestion was that it had been "injected" by the males :?: :?: :?: :?: :?: Steve do you know anymore about this? I think it was an Aussie specimen.

Cheers

J
 

Steve O'Shea

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TaningiaDanae said:
Again, fascinating. Do you suppose this implies that the female mates with more than one male during that season, or conversely, that some of the spermatophores from a single mate are retained and "portioned out" over the release of several egg-spheres?
This is a question Kat asked several days ago; strange thing, middle of last night, I awoke (as you tend to do when thinking/dreaming about squid, trying to solve a riddle) with a possible solution. I had none earlier.

How they portion it out, if they do release several egg masses, is a problem. If the male has inserted spermatophores into several of the female's arms (and this does happen) then I suppose she need only expose one of those arms to the face of the egg mass at any point in time, thus portioning their release. If she was to cradle the egg mass with all arms then I would imagine there would be uncontrolled spermatophore discharge to the face of the egg mass. It is one possible solution Tani, but I don't know for sure what happens.

The male of ommastrephid squid, the likes of Todarodes and Nototodarus, insert spermatophores around the females mouth and beaks :roll: (they do this with a hectocotylus, whereas Architeuthis does it with his 'terminal organ' (= penis) into the arms). At least Todarodes does (or can) release a spherical egg mass; cradling the egg mass in the arms, proximal to the beaks, probably does result in uncontrolled spermatophore discharge, but I believe Todarodes that have spawned in the laboratory have released a single egg mass only (prior to death).

There's not a lot known about this sort of thing - all the more reason to immerse yourself in the subject and try and figure out what really is happening.
Cheers
O
 

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