question: Octopus vulgaris distinguishing characteristics

[dreadhead]

what are the charateristics oa a vulgaris?like webbing,mantle vs arm lenght,etc...

 

[Animal Mother]

Look at www.cephbase.org

 

[monty]

what are the charateristics oa a vulgaris?like webbing,mantle vs arm lenght,etc...

Some not-that-helpful stuff from the "Cephalopods of the World" FAO report (ToLweb is much less helpful on octopus than squids for some reason):

Diagnostic Features : Medium to large sized; animal chunky in appearance. Arms stout, of about equal length and thickness, dorsal pair of arms slightly shorter; shortened right arm III of males hectocotylized by modification of tip into a very small, spoon-shaped ligula; ligula index (length of ligula expressed as percentage of length of hectocotylized arm) less than 2.5; 7 to 11 gill lamellae on outer side of gill, including terminal lamella. Geographical Distribution : World wide in temperate and tropical waters; limits unknown. Habitat and Biology : A benthic, neritic species occurring from the coastline to the outer edge of the continental shelf (in depths from 0 to 200 m), where it is found in a variety of habitats, such as rocks coral reefs, and grass beds. It is inactive in waters of 7 degrees C and colder.

and

Size : Maximum total length 1.2 m in females and to 1.3 m in males; maximum weight 10 kg; common to 3 kg. In the western Mediterranean, mantle length at first maturity is about 9.5 cm in males, 13.5 cm in females.

Norman describes vulgaris as a complex rather than a single species, says:

...longer second and third arm pairs with the front arms being the shortest. The skin sculpture consists of regular or irregular pavements of raised patches separated by distinct (and often darkened) grooves. There is a diamond of four large fingers of skin (papillae) that can be raised on the upper body... some species are "ocellate", meaning that their colour pattern includes a pair of false-eye spots in the skin over the bases of arms 2 and 3...

Nixon & Young report enlarges suckers in males, "two or three conspicuously enlarged suckers on arms II and III".

Nesis doesn't have much to add, except gory details of the hectocotylus anatomy.

None of my references mention webbing relative to any other species, although I know TONMO folks find it helpful sometimes to distinguish some species. 's memoir on octopoda of NZ mentions the taxonomic muddle of vulgaris in that there is no preserved animal or geographic distribution for the taxon, but he describes Octopus oliveri as a well-described species that's useful for comparison. I hope I'm not mangling my understanding of the terminology, but my read is that Steve thinks the qualities Robson thought distinguished oliveri from vulgaris or Octopus(sensu strictu) were things that vary between individuals. Some relevant stuff about oliveri that, I guess, might help with IDing vulgaris are: lateral keel or fold of skin absent, ventral longitudinal groove or depression frequent; brachial crown very robust, wider than head and mantle; arms thick, square in section, very short to very long (female 73-87% Total Length; male about 51-91% TL), gradually tapering to blunt-rounded tips; web shallow to deep, about 11-34% longest arm length with thick, well-developed web extension along dorso- and ventrolateral surfaces of each arm almost to tip; web formula variable, sectors A and E usually shallowest, sectors C, D, and B deeper, with no consistent disparity in sector depths; suckers biserial, with 11-13 suckers between beaks and web margin on dorsal arm pair 1; distal arm-tip suckers not markedly reduced in diameter. He also describes papillae (bumps the octo can raise when it wants) as "wartlike conical mounds" and not the "superocular cirri" ("horns" above the eyes) that some species have... I think this applies to vulgaris in general that they have lots of pimply bumps but not any "horns."

At Mote, I don't remember the vulgaris being very bumpy during the time I watched them, but octos seem to prefer being spiky when sitting still, and they were moving about the tank while I was watching.

Although it's not 100% clear that Biddle is a vulgaris, Carol has some great pictures in this thread that at least show why it's hard to nail down a "look" for vulgaris because they change so much (note, though, that there are two pics of G2, her bimac, mixed in, showing an eyespot and a that bimacs can be spiky, too.)

 

[monty]

Look at www.cephbase.org

I've been getting a lot of errors on cephbase lately; today, I get java/ coldfusion database errors when trying a species search, and some links take me to the old www.cephbase.utmb.edu which doesn't usually work. Is this just me, and it works OK for everyone else?

 

[monty]

I changed the title to be more specific, in the hopes of catching the attention of more of the busy-but-helpful experts... of course, that means Steve is more likely to me for not comprehending the terminology in his memoir....

 

[dreadhead]

thank you for your help.my little guy is crawling out of on of his rocks right now(for the second time).do you think i should wait awile to take any photos the flash may scare him.no?and no its not just you i got the same message.

 

[monty]

Some octos are fine with flashes, but some do freak out and ink and hide from the flash. If you can turn off the flash, you can take a long-exposure pic if the octo is still, but if it's moving at all (or you move the camera... a tripod would help with that) it'll be blurry. Extra lighting with a lamp or flashlight is a more gentle way to not startle your octo if it's not too nervous being out in continuous bright lights but it's startled by sudden ones like flashes, and the extra lighting can make the no-flash pictures come out better.

What kind of camera do you have?

 

[dreadhead]

we have a few cheap digital cameras,but my wife has one that i cant work yet so im sure it can take what ever kind of photo i need it to.but i think i'll wait i've only had him a week and this is only the second time he's been out.he was out during the day under lights at the pet shop but i've only seen him in the evening since i've had him.

 

[Nancy]

I doubt if you'll be able to determine the species in a very small octopus.

For a good look at O. vulgaris, watch Octopus Volcano on Animal Planet, a whole hour of wonderful shots of that species.
There are photos and videos on the Animal Planet site, too.

Nancy

 

[DWhatley]

There are also some unprofessional shots of the vulgaris at Mote under the TONMOCON thread