Squid anatomy question (& albatross diet)

[francisco]

Hello everyone:

I have noted that the jaws of the beak of some octopus are diferentiated in a lower and a upper jaw, it is possible to know for example from an unique jaw (of squid) to know if it is the lower or the upper one?

Do exist a form to know the size of the animal in basis to beak measurements?

Is the rostral length of a beak the measure from the tip of the beak to the jaw angle?, it is a straight line?, which is the proper form to measure a squid beak?

Considering the finding of rests of squid beaks in albatross regurgitations, how did the albatross got this kind of deep organisms matter?
Do Albatross feed on washed ashore squid carcasses?.

Thanks in advance for your help.

Juan Francisco Araya.

 

[Steve O'Shea]

Re: Squid Anatomy Question.

Hi Juan
Great questions!

First, images of the upper and lower beaks of a squid can be found at the following (it is very easy to differentiate upper from lower beaks of both squid and octopus):
http://www.tonmo.com/images/content/measure-fig6.gif

Based on lower beak rostral length there are many equations out there to determine the size/weight of a given squid species (not so many for octopus, because the beaks generally are more difficult to identify, less-variable between species, and less work has been done on them). Links will be posted later.

I thought there was an image online to show how to measure a beak, but I've yet to find it. Will post something shortly.

Albatross eat considerable commercial fishing trawl discards, and this partly explains the occurence of deep-sea species in their stomachs (or regurgitations). Many of these supposed deep-sea species of squid also occur in the upper few metres of the water column (at night), also explaining the incidence of them in albatross stomach/regurgitation contents. Sperm whales regurgitate the contents of their stomach (including all of those accumulated squid beaks) every couple of days (according to theory); if these/undigested squid remains were ingested by albatross then this too could explain their incidence in albatross regurgitations/stomach contents. Some of the deep-sea squid could have been secondarily ingested in stomachs of other fish species that the albatross ate. Finally, many of these deep-sea squid species are positively buoyant (at death), and their floating carcasses could be consumed by the albatross.

There is probably no one answer to your question, and undoubtedly more possible ways that deep-sea squid are ingested by the albatross than identified above. There's a body of literature discussing this.

Will post additional information soon.
Steve

 

[TPOTH]

Re: Squid anatomy question (& albatross diet)

I hope i don't say anything stupid (for a change) not that Master O is present on this thread...
Oh well, here goes:

Do exist a form to know the size of the animal in basis to beak measurements?

I believe there is a Beak Database on Cephbase (http://www.cephbase.utmb.edu/).

Considering the finding of rests of squid beaks in albatross regurgitations, how did the albatross got this kind of deep organisms matter?

As said, human activities might have a role in this, trawl and also jigging at night would bring squids to the surface waters and albatrosses would likely feed on the bycatch thrown back by fishermen (not target or undersize).
Not all species of squid are deep-sea, some shallow waters species exist too and it would be as easy as catching regular fish (and we all know how "easy" that is ) for the albatros.

Spawning events could also be considered. As O mentionned, dead squids will float to the surface, consider the "spawn and die" strategy and a lot of dead (but proud) squid parents coming up on the surface is bound to attract scavengers

TPOTH
--hoping he doesn't get beaten up by O tomorrow....*shivers*

 

[Steve O'Shea]

All valid points master TPOTH

You learn fast

jedi Master

 

[Infusoria]

Re: Squid anatomy question (& albatross diet)

I hope i don't say anything stupid (for a change) not that Master O is present on this thread...

Well, like that's ever stopped me :P

Spawning events could also be considered. As O mentionned, dead squid will float to the surface, if one considers the "spawn and die" strategy, then many, perhaps dozens, of dead (but proud) squid parents coming up on the surface are bound to attract scavengers.

I'm glad you mentioned this as I had visions of insomniac Albatross, and we (almost) all know what happens in 'Fight Club'.

 

[francisco]

Thanks!

Very interesting, thanks very much.
specially about photographies.


Juan Francisco Araya.