Why is the Giant Squid so giant?

[Steve O'Shea]

....and there you have it

Welcome aboard Armstrong; you were rather busy there yesterday weren't you ... tiz hard to keep up right now.

Are you studying cephalopods, or is this a hobby of yours?
Cheers
Steve

 

[Fujisawas Sake]

ALERT!!! NEOTENY NEWS!!!

D'OH!! *slaps head*

Sorry folks... upon further review of my notes, I should re-state the neoteny thing...

Paedomorphosis and Neoteny are pretty much the same... Neoteny is the retention of juvenile characteristics during and beyond sexual maturity... its the SAME as paedomorphosis.

BUT... there are two types:

Obligatory: Where juvenile characteristics are always retained

Facultative: Where environmental factors affect the neotenic characteristics and metamorphosis...

Thanks for your patience folks!

Sushi and Sake,

John

 

[Steve O'Shea]

Tiz all good stuff John! No head-slapping reqd
O

 

[Steve O'Shea]

Another explanation for giant squid 'gigantism' is copied below, taken from the link:

http://www.cnn.com/2003/US/South/01/23/arkansas.fossil.ap/index.html

Wherein "The professor said the cephalopod found by the students is a pathological giant, which possibly suffered from parasitic castration. In other words, parasitic algae destroyed the reproductive organs of the creature and the creature continued to grow."

....but for acquired gigantism like this to be passed from one generation to the next, as in inheritance of acquired characteristics, one would need one's reproductive organs .... and the likelihood of these being available (or existing) following 'parasitic castration' is pretty remote (having trees in your tubes sounds painful). Guess our good giant nautiloid was a dead-end in evolutionary history. I do wonder why the report singles out parasitic algae though ... have these a habit of infesting cephalopod reproductive systems?

 

[heydiddlesquiddle]

G'day Folks,
Thoroughly fascinating subjects you guys have here. I have been lost for two days in this site now and still cant find the will to move on!!!
Anyways, I am a non educated guy when it comes to scientific research, but I have spent hundreds and hundreds of hours reading everything i can about what makes animals and physics tick.
I noticed here the refections of how a squid uses his tentacles.
I am a very keen fisherman and every winter here in south east Queensland, Australia the squid come in to breed. Most of my catches of squid have been with the use of prawn style jigs or scoop nets, both used at night. I am yet to catch a squid by the tentacles on its first attack of the jig. They move in for the kill immediately with its arms as thier first attack. If I miss setting the hooks on that attempt, the squid will use its tentacles to "taste" the jig to see if its edible. If it decides its not worth trying again you will in no way entice it into another take.
As for how it postures while actively hunting under the lights, i have noticed that the tentacles will in most cases be retracted short and held slightly wider than thier arms.
There are two main types of squid here that I have access to. The most prolific is an Arrow squid, and the second is what we call a tiger squid.

I do have a question tho.

Do squid and octopus have an olfactory system of sorts for detecting scents?

I should have stayed at school and followed my childhood dream and become a biologist i think. A little late now to start uni for a degree at 38.

Keep up the fascinating studies folks, Take care and keep smiling. )

Tony.

 

[Architeuthoceras]

In the article by Manger, Meeks & Stephen I refered to in this thread (Dr. Manger is the professor interviewed in the news article above). They refer to living Giant cephalopods as phyletic giants with a reference to Cope's Rule. They also refer to living pathologic giant gastropods that have been castrated by nematodes (I dont know where the algae fits in). Alot of Actinoceroid (Rayonnoceras) fossils have been found in Arkansas that are less than 1 meter long, I think the fossil in the article is only the second Giant Actinoceroid found.

Dwarf ammonites have also been found. I have a picture on my site.
http://ammonoid.topcities.com/turonian.htm
The Pteroscaphites is considered a progenetic dwarf offshoot of the larger Scaphites.

 

[Steve O'Shea]

Do squid and octopus have an olfactory system of sorts for detecting scents?

Heydiddlesquiddle, aka Tony, howdo. I have a lot riding on this very question myself. I am aware that pheromones have been identified in Sepia (cuttlefish)......but just how many squid release pheromones I don't know (yet). This is something we are to look at this coming year.

Neither squid nor octopus have an obvious 'nose', but a system is in place, somewhere. More to follow soon.

That parasitic algal business being responsible for neutering the aforementioned beast is probably another example of the press getting things all wrong. Thanks Kevin.
O

 

[Jean]

Hiya Heydiddlesqiddle, I'm certain that arrows ( Nototodarus spp anyway!) have some sort of olfactory system, no real evidence to support this, but on the odd occasion we've held live ones, they've been held in a very large and dark tank (Steve you'll know the ones I mean, the big concrete ponds under the lab building at Portobello!) Anyhow when we've fed (or attempted to feed) them they will be nowhere in sight but shortly after the food (usually filleted fish, until such times as we can get the fish traps out to catch live food!) hits the water they appear out of the gloom. Now unless they have some sort of super xray vision, my feeling is that they smell the fish.

BTW it's never too late to enrol at varsity, my Mum has this year and she's 64 in May!!

J

 

[heydiddlesquiddle]

Thanks Steve,
I'm glad to be here learning more and more each few mins

Thanks also Jean,
I have noticed that squid can react to other senses incredibly quickly.
I fish for squid always on the new moon nights as they are the darkest and i fish on piers which have lights on them. I generally dont fish under the lights due to crowds so i move away 30 feet or more and jig the shadowed areas for better results.
During mid winter here when the squid are around, if the action is slow I will tie on a pair of bean sinkers about 2 inches long on separate loops so they rattle together with the retrieve, and cast them out as far as i can. The retrieve i make is as fast as i can wind while jigging the rod furiously. Within seconds of the sinkers leaving the water the squid will start to appear. I have counted 23 squid appearing after one cast once before but that was outstanding, usually its 6 or 8 squid that appear. This sort of brings me to thinking they use a sense of vibration as well as extremely good vision for thier major hunting techniques. I have tried fish scents in the water before and the squid only appear after the bait fish begin to school around. That's what was making me wonder.

As for going to uni and changing careers Jean, I would dearly love to do that but unfortunately atm money is my biggest hurdle. The costs for uni to obtain a degree then a masters is out of my price range until i pay this house off.

Thanks for the replies folks and i will be looking for results of more ceph data in the future.
Keep up the excellent work guys and girls )

Tony.

 

[Fujisawas Sake]

Heya!

Well, time to throw my two "scents" in (groan!) . "Smell" is kind of a relative term here, mostly since taste and smell are chemoreception, and therefore are related. I tend to think of them as pretty much the same underwater, where traditonal definition of smell doesn't quite apply here. Chems in the medium (water) are detected by cephs by a system of chemoreceptors on the suckers. So they do "tastesmell" the water.

An interesting side note: Many molluscs have small patches of sensory epithelium located near the gill or mantle wall called osphradia. These are chemosensory, and perhaps serve in bivalves as a sediment detectors. However, the only ceph with osphradia is Nautilus. I would theorize that the suckers of cephs are so specialized that osphradia would be unecessary.

Oh well... Sorry if this is a confusing post. Its late, and I can't sleep, so I decided to post. I'm wierd that way...

"Aye, breach thy last to the sun Moby Squid!"

Sushi and Sake (and Hello Panda! crackers),

John

 

[Jean]

As for going to uni and changing careers Jean, I would dearly love to do that but unfortunately atm money is my biggest hurdle. The costs for uni to obtain a degree then a masters is out of my price range until i pay this house off.

Don't I know it!!! I could buy a pretty fancy house in an upmarket part of town with my student loan!!!!!!!!

I agree that squid seem to be exeptionally sensitive with other senses, but we were keeping them with no other tankmates and out of curiousity we put the food in with a minimum of splashing. So I still feel that scent, taste, chemorecpetion .....whatever! plays a part. But vibration (& sight!) are also hugely important. When we put live baitfish in the squid appeared much faster, boy can these guys move!!!! there was definitely a different response time. With the live fish the squid "noticed" them far faster than with the fillets!

J

 

[Fujisawas Sake]

Jean,

Actually I agree wholeheartedly with you about sight and vibration. The cephalopod eye is unequaled among invertebrates, and vibration makes perfect sense considering the medium in which the creatures live. I personally believe that the squid is the molluscan "fish", that is, the molluscan answer to the ecological niche need for a raptorial predator. If you think about it, the shapes are similar, and the types of prey are also pretty much the same. Yeah, its not as convergent evolution as the shark/dolphin/icthyosaur, but pretty darn close.

I guess I tend to see patterns in nature...

Now why am I so lousy at calculus?!??!

Sushi and Sake, and Gnarly Teriyaki,

John