Lepidoteuthis - with scales.

[Phil]

The old 1896 woodcut I have just bought (photo on the Antique Ceph Print thread) mentions on the reverse an unusual squid covered in scales known as Lepidoteuthis. I was not aware that any squid had such a feature. I have looked up this animal on the Tree of Life project and there are indeed some interesting photos that confirm this.

I was wondering what exactly is the function of these scales or 'dermal cushions' as they are referred to, as this is such an unusual feature?

Photos here, if anyone would like to take a look:

Lepidoteuthis Tree of Life page

 

[Steve O'Shea]

Phil, there's a rather interesting paper due out in August that deals with Lepidoteuthis .... very interesting that you should bring this, of all genera up at this point in time. Another genus with scales/dermal cushions is Pholidoteuthis, and we're in the midst of preparing a paper on this genus also.

Both Pholidoteuthis and Lepidoteuthis used to be placed in the family Lepidoteuthidae, but Pholidoteuthis was separated out some years back and is now in its own family, the Pholidoteuthidae.

The scales could have several functions. Lepidoteuthis is quite closely related to species in the Octopoteuthidae (Octopoteuthis and Taningia)..... another family of squids that we're working away on (have several specimens of a giant Octopoteuthis to try and name, and a few other quite confused species to tag names to ... but the group is really quite complex and the systematics in disarray). More to follow, some soon, a little in a few months.
O

 

[Phil]

As a bit of a historical aside, Lepidoteuthis appears to have a quite interesting story concerning its discovery. It was actually discovered on a ocean-going expedition by the Crown Prince of Monaco Albert Grimaldi (Albert I) (1848-1922) and was named by a naturalist companion in his honour, literally ‘scaly Grimaldi squid’.

Despite being a veteran of the Franco-Prussian war and heir to the throne, Albert was apparently an accomplished mariner and oceanographer, mapped the gulf stream and commissioned a map of the seafloor in the Atlantic. He collected thousands of marine specimens and made surveys of plankton in the Atlantic. He even had a series of four large steam yachts built for the purposes of marine research! Albert dissected the first recorded Lepidoteuthis after seeing it vomited from a sperm whale stomach. Another squid was named after him was caught in the Azores in 1898 called Grimalditeuthis. It’s a pity that the travels of this ocean-going royal personage came to an end with the outbreak of World War I, he was too sick to continue his explorations in 1918.

It’s hard to imagine a modern Royal engaged in scientific research these days. I can’t really see the Queen of England poking around a sperm whale stomach contents or hauling in a deep water trawl net. Pity.

 

[Steve O'Shea]

...a great pity indeed. They seem more concerned with polo than deep-sea exploration; with all of that money they could fund some pretty spectacular expeditions.

Perhaps I should invite Queeny along?

 

[Fujisawas Sake]

Cool.

So here's my two cent question: why the scales? I wonder if they're an evolutionary throwback, i.e. "reverse-evolution" (I hate that term too, but I can't think of any better ones right now) point mutations along Hox genes? Or are they some kind of adaptation, like a mutant variety of skin cell?

Sorry about the "throwback" remark, but I still think that there's some ancient mollusc link that still might be encoded in deep time DNA.... Some link to the past and where exactly they came from.

Oh well.

Anyway, this post is related to an earlier post on the Fossils and History section. I wrote something under "New Article on the Cephalopod Page" about the evolutionary theories behind molluscs (at least the ones with which I'm familiar) and I wonder if the scales might have to do with the evolutionary history of cephs?

Sushi and Sake,

John

 

[Steve O'Shea]

Funny that you should raise that question today John - I was reading up on the exact subject matter this afternoon. ..... Morrow I'll transcribe the theory advocated by Roper & Lu, a few years ago now, in a comparative study of dermal scales in a few genera (Lepidoteuthis, Pholidoteuthis ... could have been more).

As an aside, for a future discussion, here's a term for you: atavism. What do you make of this?

Back to the subject at hand though, we're working on both Lepidoteuthis and Pholidoteuthis at present (and this rather bizarre, possible synonym, Tetronychoteuthis .... although I'm not entirely convinced); only Lepidoteuthis has the 'real' scales. Keep your eyes on the JMBA website for an upcoming article/August release ..... it will help explain a few things. Tony has a sneak advance copy, so the minute it's out we'll have it online here anyway.
Cheers
O

 

[myopsida]

It’s hard to imagine a modern Royal engaged in scientific research these days.

Emperor Akihito of Japan has published extensively on pufferfish taxonomy (Fam. Tetraodontidae). But since he got the job full-time he's been otherwise preoccupied with other things.

 

[Fujisawas Sake]

As an aside, for a future discussion, here's a term for you: atavism. What do you make of this?

Point well taken.

That's a tough one. See, I think that there is a possibility, however remote, that ancestral traits "lost" along the evolutionary path are still encoded in DNA. albeit sleeping between relatively recent STOP and START codons. There is a lot of so-called "junk" DNA in our systems that many scientists believe is the sloppy work of viruses trying to get a foothold in our cells. Then there are small, quiet mutations, etc. that can occur. Its a mess, but probable.

My take is that maybe the scales may be an atavistic expression of earlier model teuthoids or their molluscan ancestors, brought to the surface and recombined with current features. Or maybe, they are further proof that the squid is the molluscan raptorial "fish" form.

Just what are the scales used for anyway?

John

 

[Steve O'Shea]

I'll probably have to correct this post tomorrow coz I'm indulging in a much-needed

I recall reading that the scales were actually vacuolated (some neat SEM shots), and the theory advocated by Roper & Lu was that these vacuoles were full of ammonium ions, thus rendering the animal neutrally buoyant in the water column. Now I could be totally up the creek ( ) in a little canoe, as Kat is as we type, but I'll check it out again tomorrow and post away.

The atavism comes in later .... watch this space
O

 

[Steve O'Shea]

But since he got the job full-time he's been otherwise preoccupied with other things.

What's his new job that keeps him from his science? I mean, like what does an emperor do all day? Oooops, too much

Toodles, O

 

[myopsida]

I mean, like what does an emperor do all day?

Looks for his new clothes?

 

[Fujisawas Sake]

The ammonium vacuoles would make sense as a buoyancy adaptation, although its eerily looking more and more fishlike. What's next, swim bladders? Gee...

Why wouldn't they just retain the ions in their flesh? And is this the case across the entire Pholido- and Lepidoteuthidae families?

Heh heh... These body plans just get weirder and weirder. If in the future I'm sitting on a tropical beach somewhere, and some scaled octo comes out of the surf, slides up to me to ask me for some raspberry sake, I'm quitting!

Sushi and no sake for octo!

John

 

[Steve O'Shea]

There is an octopus with a 'swim bladder' - a very bizarre arrangement. It is found in the female of Ocythoe tuberculata, but I'm not sure if the male also possesses this structure (the female is considerably larger than the male); family Ocythoidae, monotypic.

I've only ever dissected one mature female (they're quite scarce); they also brood embryos in their distal oviducts - another very bizarre attribute for a cephalopod.

I agree with you John that they might as well distribute ammonium ions throughout the body tissues if achieving buoyancy was the sole purpose of these scale-like structures in the Lepidoteuthidae and Pholidoteuthidae. Lepidoteuthid squid are way-cool (and very rare, at least in collections) squid!!!
Cheers
O

 

[Phil]

There is an octopus with a 'swim bladder' - a very bizarre arrangement. It is found in the female of Ocythoe tuberculata, but I'm not sure if the male also possesses this structure (the female is considerably larger than the male);

Steve, I know this is not my section so I hope you don't mind me posting this, but I could not resist!

I've just looked Ocythoe up on the Tree of Life Pages, there is a nice diagram of the swim bladder here:

Ocythoe Swim Bladder

It does appear, from this site, that this structure is only present in the females. This species displays extreme sexual dimorphism with the male at about 30mm being about a tenth the length of the female. It also mentions that Ocythoidae are the only octopus family that bear live young, with the juveniles hatching in the oviducts. Is this truely a unique approach amongst the cephalopods, or are there others?

The male has also been known to hide inside the bodies of salps (free swimming sea squirts), leaving the protection when approached and retreating when the threat has passed! (Source here: Mark Norman's Cephalopods: a World Guide).

It really is quite astounding the sheer diversity of body plans and differing functional mechanisms within the cephalopods. So many different approaches to the same problems, and so many resolutions.

 

[Phil]

See, I think that there is a possibility, however remote, that ancestral traits "lost" along the evolutionary path are still encoded in DNA. albeit sleeping between relatively recent STOP and START codons.

Hope you don't mind me risking sidetracking this interesting discussion about Lepidoteuthis, but I once saw a fascinating TV documentary that demonstrated your point, John. I am not exactly sure how it was done but a certain section of DNA coding was chemically 'switched off' somehow in an embryonic chick. The section that was turned off controlled the formation of the beak. When the chick was X-rayed a few days later it seems that instead of a beak fully forming, rudimentary teeth began to develop along the jaw. The idea here was to demonstrate the dinosaur/bird link and that 'fallback' structures are indeed encoded in DNA. Atavism indeed!

I freely admit I do not understand genetics in any detail. Would the sequence of genes that caused the teeth to form been a recessive trait?

You might like to look this up, the experiment was three or four years ago. Anyway, back to the squid........