Malacology - H.G. Wells Style

[Fujisawas Sake]

Hi,

Well, this thread is my split and an apology for getting off the previous subject of "Why Are the Giant Squid so GIANT?". A little background: I was curious about what the past held for cephs (their evolutionary lines, especially ammonites - SERIOUS controversy there), as well as what size and forms cephs have today and what shapes they may take in the future.

*ahem* Anyway... When last we left off, I was wondering about the possibility of ammonites being paraphyletic, or just what form or forms they could have taken, as well as the weird "The Future is Wild" idea of land squids and such. Only time will tell....

[Phil]

Hi.

I think you will enjoy these fantasy constructions of possible ammonite descendants:

http://users.macunlimited.net/n.monks/ammonites.html

Neale Monks is a palaeontologist at the Natural History Museum in London who specialises in ammonites. I'll write something a bit more detailed soon (bit busy at the momnent, for once).

Phil

[Fujisawas Sake]

Schweet! Thankee-sai, Phil!

Well, I'll click on that link ASAP. I was hoping to find some more info. I have an invert zoo text that might be helpful. Its at home, which is about 1800 miles away right now :cry:

Steve, if you read this post: I was thinking about a land walking Ceph a-la "The Future is Wild"... At the 100 million year mark is the Swampus, which can survive for up to four days out of the water...

Here's my two cents: What about the evolution of a closed, negative-pressure mantle, and a "book lung" modification of the gills? I guess it would be a type of pulmonate ceph, and it would have to be small, but if the mantle was modified into a "lung" like the pulmonata, it could be done. As far as movement, muscular hydrostats only go so far, but a small form might make it. Any thoughts?

Sushi and Sake,

John

[Steve O'Shea]

It is possible (this lung business), but that there terrestrial squid would be one lethargic thing; not sure what sort of acrobatics pulmonates can get up to, but I don't think they're the most exciting (behaviorally) of molluscs. Probably the lungs ratio of surface area (for O2 absorption) to volume would not allow the terre-squid to get up to much, except maybe chase fungii.

Having said this, a colleague at work recently returned from a wee trip to collect copepods from leaf litter ... and basically dry leaf litter at that. In minute droplets of water on these very dead leaves she found a startling diversity of copepods (I wouldn't have thought it possible). So, maybe, just maybe, a small octopus-like animal could slither its way through more moist leaf litter in some futuristic rain forest environment. Just one problem, and that is no ceph occurs in fresh water, but so as long as it rains salt, the ground is salty, or the ceph one day can tolerate non-marine conditions then you just might encounter them. If you do I sure hope they have the equivalent of the rattlesnakes thingymajig, coz I'd like to know if something like that was slithering around my toes.

Phil, I think we're going to have to design our own ammonites!
Cheers
O

[Fujisawas Sake]

Steve,

Actually, that doesn't surprise me. Copepods are one of the most adaptive Crustacean groups you can imagine. They're also found in peat moss as well as marine and freshwater habitats. Also, the Phylum Tartigrada (water bears) are always good for a few "oohs" and "ahhs" (as well as the occasional "Aww, that's so cute!") from a class, and they're found around areas like that. If you have the time, study the body plans of the parasitic copepod species... WOW!!! I mean, talk about bizarre.

Discovery Kids had a ceph special today, and showed a very diverse selection of ammonite shell designs. They also mentioned the belemites, which seems to point out squid evolution, but I'm wondering about the Octos and Vampyros and such... I wonder when they came about?

Anyway, I'm absolutely STOKED!! I went to the Houston Museum yesterday and saw a maned wolf, Chrysocyon brachyurus. Its a really tall canid that hunts in tall grasslands in South America. I've only seen them in pictures! I took some photos! I can't wait to get home and download them from our digicam.

Well, I may not be posting until Friday, as I have to head back to California tomorrow. If I don't see you before, have a great New Years!

P.S. "Rattlesnake Thingumajig"?

[Steve O'Shea]

.P.S. "Rattlesnake Thingumajig"?

You know, the bit wot rattles down the non-bitey end (not quite the blunt end - snakes seem to have two pointy ends :) ). What do you call it? A rattle? Must have a better name than that - the dictionary describes it as "loose horny segments on the tail", but I'm sure someone has come up with a more techo term than rattle.
O

[Fujisawas Sake]

Its pretty much "rattle"... sorry... If it makes you feel better, the rattlesnake subfamily (Family Viperidae, Subfamily Crotalinae) is considered the most advanced species of Viper.

[Fujisawas Sake]

Steve,

Here's the skinny on "The Future is Wild": The big 8-ton land walking squid is a biomechanical puzzle... I read the companion book to the series, and while I get it, it does sound wonky at best. Using a system of circular and vertical muscles to compensate for skeletal muscles....
W E I R D ....

Honestly though, do you see freshwater tolerance as a future step for cephs? I mean osmoregulation aside. What about communal behavior?

[Fujisawas Sake]

Oops.. another thing:

How old is the Phylum Mollusca? Around what period did they appear?

[Phil]

How old is the Phylum Mollusca? Around what period did they appear?

That is indeed a very interesting question. Mollusca are represented in the early Cambrian period (550-490 mya) in very simple cap shapes, though most of the 'modern' forms of mollusc appeared during the late Cambrian/early Ordovician radiation. What is debated, as far asI know, is whether the 'later' more complex forms represent a continuation of the early lineages or whether the early Cambrian forms were not directly ancestral.

One fascinating creature worth looking up was a strange creature called Wiwaxia that has been found in rocks of middle Cambrian date (525mya). This creature was hump shaped, had a foot like a mollusc and was covered in scelerites or scales with two rows of spine-like blades running across its back. It was believed to be a very primitive mollusc though recent work has placed this creature on the lineage that led to the annelids. Microscopic studies of the scelerites reveal basic structural simularities to the chaetae (stiff hairs or bristles used in locomotion) in polychaete worms. From this it seeems that the molluscs and annelids may have a close ancestral affiliation in the early Cambrian. As for what the actual common ancestor looked like, no specimen has yet been found and educated guesses can only be made as its appearance.

As for cephalopods, the earliest creature that I am aware of was called Plectronoceras which dates from the upper Cambrian and was found at Shantung in China. Shells of this 2 inch long tiny creature were horn shaped but show clearly defined chambers with a siphuncle. A reconstruction I have depicts gills, tentacles and the classic molluscan foot. It was believed to be a creeping bottom dweller as opposed to being an active swimmer.

Hope this is of some interest, Phil

[Fujisawas Sake]

Phil,

Thanks a lot! I wouldn't doubt the annelid-mollusc link. An old invert. zoo instructor I had was a little too cladogram-happy, BUT his links between phyla did pique my interest.

The "cap" shapes I'm assuming are shells? Maybe ancestors of the Monoplacophora? I still think that there may be a distant relation between the Molluscan Aplacophorans and Caudofoveatans with the coelomate worms like the Sipunculans and Echiurans... Any thoughts out there? The "aps" and "cauds" are more "simple" (*shudders*) but I have no idea if they're more ancestral or derived.

Sorry about the shuddering :D Its just that I have found myself defending evolutionary theory lately to more and more people and many either cannot or will not (more likely the latter) try to understand that "simple" and "complex" are pretty relative terms in evolution and that forms evolve to suit the best niche. Heck, look at parasitic copepods! They are SOOOOO simple in form yet are the product of countless generations of specializations. For a really creepy crustacean, look up the Rhizocephalan. It starts out a cyprid, and ends up a decapod's worst nightmare... I doubt even H.R. Geiger could come up with something that scary - and he created the Alien.

Sorry about the rant, and I mean no offense to you by it. I always use the words "simple" and "complex" and seem to get them thrown in my face again... :lol: I can imagine my old zoology instructor spinning in her grave... and she's far from dead! :lol:

Interesting thing about the early ceph. Kind of a "gastro-ceph". I wonder what intermediate forms looked like? If you have any more mollusc art links, can you hook me up? Thanks again Phil!

Sushi and Sake,

John

[Fujisawas Sake]

Addedum: I think that the Caudofoveata bear some more investigation. An annelid link sounds pretty reasonable too. I think it would have to do with the chaetae-like structures mentioned earlier. "Cauds" also have imbricating calcareous(?) scales and/or spicules....

Hmm... definitely a pattern forming here...

As far as the cephs and their forms and history go, his leads to a very interesting thought; the diversity of the molluscan bauplan and its evolutionary history leads me to believe that they were once pretty much large and in charge, right? I mean, adaptive radiation of this sort seems to mean a dominant spot in the ecosystem if I'm not mistaken. Any thoughts out there?

(Sorry if I'm sounding like an overexcited kid here. Keep in mind, I'm not a malacologist, let alone a zoologist... Yet! :lol:)

[Architeuthoceras]

I think the Ordovician period was the age of Nautiloids (Molluscs), 500 to 440 mya. The largest animal on earth was a 9 meter (30 ft) endocerid (that number is probably passed around like the 60 ft architeutis). There were more familys of cephalopods then than any other time in earth history. Their radiation was possibly in response to being able to float above their food source, Trilobites. And as fish started to appear in the next couple of time periods the nautiloids began to diminish. I think most of the other molluscs had a great radiation in the Ordovician as well.

:nautilus: :snail: IMHO

[Steve O'Shea]

NINE METERS :!: :!: :!:

Kevin, we've got to get to the bottom of this!!!! I am rapidly losing interest in Recent cephalopods!!! Can you provide further details?

[Fujisawas Sake]

Okay, NOW I'm embarassed.... what is an endocerid?

*looks it up*

Well... Now I know... Darn, shoots my pteropod theories out of the water. I still think that there is more than meets the eye here. What does a 30 ft endocerid eat (besides the obvious answer -- "anything it wants")? Somehow I wonder just how much more diverse the mollusc bauplan was before? Just HOW many forms did they take?

Strange... cephs have become so streamlined in design... Without the teleosts, they might have been even more of a dominant force in the oceans. Or maybe they are yet to have their time in the proverbial sun.

*yawn* Only time will tell...

Sushi and Sake,

John

[Phil]

John,

Thanks for the info about the Rhizocephalan. I know one shouldn’t be emotive about behaviour patterns but what a horrific creature! Hadn’t heard of that one before; much to my regret I read about it whilst eating a prawn sandwich. Bad idea.

Going back to the origins of the mollusca there have been a few interesting finds in recent years, notably a strange beast known as Kimberella that was described about five years ago and was discovered at the White Sea in the Arctic circle on the north coast of Russia and dates to about 550mya. This places it almost immediately before the Cambrian ‘explosion’ that gave rise to modern bauplans in a remarkably short space of time. (hotly debated, most estimates say about twenty million years). Kimberella is interesting as it is difficult to interpret but is thought to be an early mollusc. Physically it looks like a jellyfish without the tentacles but has bilateral symmetry and a tough (non-mineralised) but flexible shell. Some fossils apparently display a mollusc type foot and although no radula has yet been found associated with this animal, as far as I know, not all mollusc fossils do.

Trace marks and scrape marks in some late Precambrian sediments may well have been caused by a creature such as this or even its ancestor. Trace marks date from 565mya or even earlier so there must have been some ancestral creature that lived in a mollusc fashion scraping up algae at this even earlier date possibly as far back as 620mya.

Other early (probable) molluscs are evident in the Tommotian faunas from Siberia (about 530mya) which largely consists of many tiny shells, many of which resemble monoplacophora. There are many varieties of cone, spiral, horn-shape and tube evident though whether or not they were molluscs depends on how a mollusc is defined, I suppose. Try doing Google searches under Tommotia, Yochelcionella or Latouchella if interested. Following this is the sudden evolution of modern body plans during the Cambrian ‘explosion’ including the arthropods and although probable molluscs were evident (re: Wiwaxia above) the relationships of these creatures to each other animal groups has been the source of much debate and study recently. All very complex.

I still have not discovered a cephalopod earlier in date to Plectronoceras (Upper Cambrian). I attach a copy of its anatomy here. I had to copy it from a text book to avoid copyright problems duplicating it here. It is quite probable that Plectronoceras evolved from something very similar to Latouchella as they do look similar (from drawings in textbooks, that is!)

On a different note, I think that 10m long Nautiloid was called Cameroceras. Must look that one up.

Phil

(PS If I have made any mistakes above I apologise. I have never actually studied zoology or palaeontology and am working out of a few books at home. All very interesting, isn’t it!)

[Fujisawas Sake]

Phil,

HA HA HA HA!! :lol: Well, if it makes you feel any better, the favorite host of Rhizos seems to the "dungees" (Dungones Crab(sp?)) Cancer magister here.

Yeah, the Rhizocephalan is a +100 on the freaky scale... but nontheless a miraculous lifeform. Just a testament to the power of life and its many forms. How hardy life on Earth can be!

Thanks for the info and the pic... I'm going to find some more information, now that I have some (scientific names).

Sushi and Sake,

John

[Steve O'Shea]

Here's an interesting link to Cameroceras:

http://www.palaeos.com/Invertebrates/Molluscs/Cephalopoda/Endocerida.htm

Hooked on fossils
Cheers
O

[Architeuthoceras]

Steve,

I can't find a specific reference to the 9 meter (30 ft) Endocerid, but almost any book on fossil cephalopods quotes that number. Even Teichert (1964, Treatise on Invertebrate Paleontology, Pt K, Mollusca 3,) mentions The 9 to 10 meter number only in the introduction to a couple of chapters. Manger, Meeks, and Stephan, 1999, Pathologic Gigantism in Middle Carboniferous Cephalopods, Southern Midcontinent, United States, in: Advancing Research on Living and Fossil Cephalopods, edited by Oloriz and Rodriquez-Tovar, Kluwer Academic/Plenum Publishers, have a nice summary of giant fossil and extant cephalopods with many specific references (but they only refer to Teichert for the 9 meter Endocerid). The longest Endocerid I have found is only 450mm. You can see a picture of an Endocerid on my web site

http://ammonoid.topcities.com/whiterock.htm

:nautilus:

[Fujisawas Sake]

"Archi" and Steve,

Thanks for the links!

Well I'll be a monkey's siphuncle! There are more ammonite sites than I thought....

[Steve O'Shea]

Perhaps someone a little more familiar with the web/with ammonites could compile a list of ammonite or ammonite-related sites. :)

[Fujisawas Sake]

I was doing a little pleasure reading yesterday. My old invert zoology book Invertebrates by Brusca and Brusca has several branches of possible molluscan phylogeny, but nothing concrete. The funny thing is I have the feeling that there's a lot more to the origin of the cephs than ammonites and belemites, but I'm not sure what that may be.

Evolution: The itch you just can't scratch without a little spectacled beagle and a Way-Back machine...

Still though... Does there seem to be any indication of punctuated equilibrium along the cephalopod line? Any quantum leaps in ceph evolution over the last few hundred million years?

Sushi, Sake, and Pocky

John

[Architeuthoceras]

I think phyletic gradualism in ammonoids is what makes them such good index fossils. Except for "punctuated" radiations after major extinction events, the ammonoid line is fairly smooth from their appearance in the Late Silurian?/Early Devonian, until their disappearance at the end of the Cretaceous.

Coleoids (with hard parts) appear in the Early Carboniferous. Could a cephalopod without recognizable or unfossilizable hard parts or without hardparts at all have evolved at the same time? Or even before? The great diversity of living cephalopods makes me think......

Where is that Wayback Machine?

:nautilus:

[Fujisawas Sake]

Maybe this is a weird question, but why aren't there any freshwater cephalopods? I mean, considering that others molluscs managed to colonize freshwater and land, it stands to reason that at least a FEW species of ceph might have tried... Any thoughts?

Sushi and Sake, and the occasional glass of Kirin Rose Life Milk Tea,

John

[Fujisawas Sake]

Heads up!

Starting July 8, "The Future is Wild" will be shown on Animal Planet as a new weekly series featuring all new weirdies from the far future! All hail the molluscan overlords! Who'll be making pearls NOW?!?!?

Sushi and Sake, but hold the Tako-Yaki

John

[Clem]

All,

Well, I'll be a monkey's nephew...

Just learned that H.G.Wells was a pupil of Thomas Huxley's. A nifty biographical detail, isn't it?

Clem

[Phil]

Are we talking Huxley as in Darwin's Bulldog? The man who destroyed Richard Owen?

Who wouldn't have loved to present in the great debate between Huxley and Bishop Wilberforce, IMHO the first and greatest direct clash between religious doctrine and emerging evolutionary theory. Oh, to be a fly on the wall (in a top hat).

Didn't know that!

Phil, (not at all in a pretentious mood).

[Clem]

Are we talking Huxley as in Darwin's Bulldog? The man who destroyed Richard Owen?

The very one.

The authors of the recent book "The Mistaken Extinction" had a little fun with poor Owen, presenting his own personal evolution in photographs: from strapping young man to hollow-eyed wretch. A wicked "in" joke, but payback's a-

:wink:

Clem

[Phil]

Sounds great, I'll have a look out for that one.

Was it written by Gideon Mantell's great-great-grandson by any chance? Just desserts, methinks! :twisted:

[WhiteKiboko]

Are we talking Huxley as in Darwin's Bulldog? The man who destroyed Richard Owen?

The very one.


would that be any form of kin to the writer aldous? (i know he came from a biology/science oriented family)

[Clem]

WK,

That's a damn good question. I'll go a-hunting.

:?:

Clem

[Clem]

would that be any form of kin to the writer aldous? (i know he came from a biology/science oriented family)

WK,

:notworth:

I went a-hunting, and you guessed right: Aldous was the son of Leonard Huxley, one of Thomas's children. Quite a little science and letters dynasty, those Huxleys.

Clem