Squid sp identification? Please help...

mcscholl

Larval Mass
Registered
#1
Good morning...

Yesterday I encountered a large Squid of the southern coast of South Africa and I was wondering if someone could help me identify the Squid Species...

As you will gather from my web site, I am not a Cephalopod specialist, but rather a Shark biologist.

Anyway, here are some pictures of the Squid in question:

http://www.WhiteSharkTrust.org/gallery.html

Then click on page 5 of April 2004, and you will see some photographs of the Squid I am trying to identify (note: I wrote there that it was a Diamond Squid from early confirmation, but after looking up some info on the web about these Squid, I have my doubts about the true identity of the Squid).

I thank you in advance for your help and I look forward to hear from you...

Take care and have a very nice Easter Weekend!

Friendly yours,
Michael Scholl
 

Steve O'Shea

Colossal Squid
Supporter
#5
It certainly is a species of Tremoctopus, a female (the male being considerably smaller), but which one I would be reluctant to say, based on the images alone.

Thomas (1977) reviewed species of the genus Tremoctopus and recognised two valid subspecies of T. violaceus, T. violaceus violaceus and T. violaceus gracilis, and a second species, T. gelatus. I (O'Shea 1999) resurrected another species, T. robsonianus Kirk, 1883, from synomymy of T. v. violaceus, so that three species were recognised, T. violaceus with the aforementioned two subspecies, T. gracilis and T. robsonianus. Males of T. v. violaceus and T. v. gracilis can be distinguished by the number of distal transverse sucker pairs on the hectocotylised arm: the former with 15-19, the latter, 19-23; the male of T. gelatus was unknown (in 1999, when I researched the group; I don't know whether it has been described yet, but I doubt it); T. robsonianus has 27 or 28 distal transverse sucker pairs on the hectocotylised arm.

Female Tremoctopus species have proved difficult to distinguish. The distal oviducts of T. robsonianus are exceedingly long and convoluted, differing markedly from those of T. violaceus violaceus, T. v. gracilis and T. gelatus (in each the distal oviducts are depicted as short, each having a pronounced distal dilation).

You mentioned something about the animal carrying eggs. This is of great interest. I don't suppose you have any pictures of this do you? Female T. robsonianus do brood the eggs in the distal oviducts (as eggs contain embryos, indicating fertilisation is internal, occuring within the ducts somewhere (or possibly even in the ovary sac)). If they brood eggs in the oviducts then it is also of great interest that they brood eggs in the arm crown (I assume this is what was happening, unless there was a discharge of eggs from the mantle cavity during trauma associated with collection).

I'll find out the geographic distribution of Tremoctopus species to assist with placing a name on this particular specimen, although precise identification (based on those characters/character states that we recognise differentiate the various taxa) would really require the body (anatomy) of the animal be examined. T. robsonianus is presently known from New Zealand waters only, but it could well have a considerably more extensive distribution than presently recognised (very likely into South Australian waters also).

Refs:
O'Shea, S. 1999. The marine fauna of New Zealand: Octopoda (Mollusca: Cephalopoda). NIWA Biodiversity Memoir 112: 280pp.

Thomas, R.F. 1977. Systematics, distribution and biology of cephalopods of the genus Tremoctopus (Octopoda: Tremoctopodidae). Bulletin of Marine Science 27: 353-392.
 

Members online

No members online now.