Largest marine creature ever

Originally posted by rider We can't really get a comparision if we don't have a picture of a human standing by the animal... so... can we get one? And the largest marine creature ever is the USS Enterprise...

Actually, the BBC show used, lets say, some gigantic artistic lincense regarding the size of the Liopleurodon - They just came up with the size almost out of the blue. They even half admit it on the walking with dinosaurs page (Don't know if it's still there.)

I think this is the longest, the ribbon worm:

I guess there is the chance of discovering a sauropod larger than the blue whale. However, with that sheer mass comes fatal ramifications in the bone structure, muscles and circulatory system. Also, for something that huge to stand up, its legs would need to be a lot larger than stated on the website.
Nevertheless, we should never dismiss the idea, and it would certainly be a pleasant surprise to come across something of gargantuan proportions...

- Knights -

That is a strong possibility, but I am more concerned about they weight and structural arrangement of an animals able to grow larger than a blue whale, and live on land. I don't think most bone would be able to withstand such pressure, especially during locomotion.
Air has very little buoyancy, while water is rather buoyant, allowing for the monumental mass of the Blue Whale, as it supports the huge build of it. Being less downward thrust on the blue whale in water, less stress is placed upon its bones and organs.
Here's an example, when a large whale such as a Sperm, Humpback, Blue or even Killer Whale become beached, there are two serious problems that need to be attended to:
Firstly, and most obviously, dessication/dehydration. The whale is susceptible to drying out if water is not administered regularly. This is the case for smaller cetaceans such as pilot whales, porpoises and dolphins.
Secondly however, air having next to no buoyancy, a great deal of force due to gravity is placed upon the whale. This can be a serious ramification for anything in excess of 5-10,000kg. With such force being put upon the large mass of the whale, internal organs begin to suffer. Many can rupture, and blood vessels can burst - which is very serious indeed.
Keep in mind though, a terrestrial animal does have leg bones to help support it to an extent.

So basically, my main concern with any terrestrial animal weighing 200,000kg + is the force placed upon their huge mass, and the detrimental consequences on organs, bones and circulation.

- Knights -

Yes that's the thing, while the oceans harvest billions and billions of krill/phytoplankton/zooplankton, just floating, and there for the taking by a behemoth like the blue whale, the atmosphere does not contain such nutrients and organisms, to allow huge animals to feed. I mean, of course there is the grass, but didn't sauropods tend to be browsers?
Still, I will not rule out the possibility of such a gargantuan organism, living on land.
Digestive and respiratory (cellular and breathing) efficiency is definitely a major factor needed to be taken into thought. While the food might be there (grass, or even browse...), whether the organism can digest efficiently. Ruminants counter the problem of thick cellulose and lack of nutrients in vegetation with their four stomachs, the caecum and 'chewing the cud'. There are several other advantages to chewing the cud, but won't delve into them...
So if oxygen levels were sufficient, necessary physical and physiological adaptations (even behavioural) were adhered to, and there is a plentiful food supply, I see it as plausible.
The only major obstacle to me still, is the structural/bone ramifications.

- Knights -

I believe the Russian Typhoon Submarine (the class, at least) is the largest sub, and there are plenty of subs larger than Blue Whales.
The Typhoon is 175m long and weighs almost 50,000t underwater, to the Blue Whales 30m and up to 200t. Just a tad bigger...

The largest vessel in history is the Norwegian supertanker "Knock Nevis" I think. It is 458m long, 69m wide and can weigh up to 647,955 t with a full load...pretty huge!
http://www.designcowboys.net/Yamato/Images/allships.jpg

I would say the larger the animal the nearer to extinction. Why have a gigantic creature when packs of smaller creatures can evolve and adapt to take them out? Why the blue whale survived I don't know, perhaps it's ability to dive to escape danger and the enormous power of its tail. The krill feeding is a  survival advantage in that it cannot deplete the stocks of other fish and so destroy the food supply chain for it's own species. Across scores of millions of years that has happened often enough.  

They truly are colossal aren't they! However, I've always thought one of the most mysterious and evil looking of the creatures of the deep was "Vampyroteuthis infernalis". Literally, the "Vampire Squid from hell".

http://www.tolweb.org/Vampyroteuthis_infernalis