Square Cube Law and The Titan Whale

Question

Alright, whale first, question after.

The Titan Whale is a massive cetacean that superficially resembles a blue whale with a few notable differences.

1. The Titan has four fins, (not including the dorsal fin) roughly corresponding to the position of limbs on a terrestrial quadruped. These fins are proportionately larger than those of a blue whale.
2. The Titan possess two blowholes arranged in a line along its dorsal surface.
3. The whale’s final life stage sees it grow to massive sizes > 1,000 feet up to ridiculous size (TM).
4. The whale is capable of eating a much wider variety of foods, including plant and animal matter.
5. The Titan possesses a special organ in its mouth and throat that unfurls into a very large, branching, tree-like filament structure that filters small food from the water, entangles larger prey items, participates in respiration by absorbing oxygen and releasing CO2, and releasing heat, thus cooling the whale.

The Titan whale behaves very similarly to blue whales and sperm whales until it reaches its final life stage. As it begins to reach its maximum size it becomes more solitary and spends the majority of its time floating lazily in the open ocean, passively absorbing food and nutrients and only rousing for more worthwhile prey or to graze on aquatic mega-flora.

So I know that a creature this size is a bit ludicrous, and that it has a lot of issues due to the square cube law, but I would like to reduce the necessary amounts of hand waving and unobtainium. My question primarily concerns #5 on the list above. Basically an extendable organ that is both a digestive and respiratory organ all rolled up in one. This should help cool the animal and aid the issue of getting enough food and oxygen. So now here comes the question,

Is an organ like this biologically possible? Of course, all extra information and opinions on how it would look and function are welcome. If the organ isn’t possible as described, why not and what could be done to fix it?

PS: Sorry for the long post and extra info, but I may link back here later and I don’t want to have to type all this over and over again.

Answer 1

Totally Possible

First, this is a fictional world, maybe a fantasy world, so we don't care so much about the square cubed law. The world is what it is; the creature is what it is; and it's our job to deal with it!

Baleen
As described, you're multifunction organ is analogous to the sea water straining fibres of baleen that many whales already use to capture food. Real baleen is keratinous, like hair or finger nails, and is thus biologically "dead".

What your titan whale will have is some kind of semi-rigid structure, it could be keratinous or perhaps cartilaginous, that will be covered with a tough gum-like tissue (for strength) and a gas exchanging mucosal layer (like gill or lung tissue).

Making the structure "extendible" can be done in a couple ways. Perhaps this whale has a pair of accessory / lateral tongues from which the gill plates extend. So when feeding, the plates are close together in the mouth, like baleen, so food can be filtered; but when used as accessory respiration, the whale sticks out its tongue and fans out the plates.

This kind of whale could have plates that arise from the mandibles, maybe split (non-fused) mandibles that could open in a terrifying display of reddish pink ship swallowing horror!

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Note: we dó like The Square-Cube Law!

Answer 2

Animal cells mostly consist of water. Oceans consist of water. This is why bodies in water seem almost weightless. In theory, aquatic animals could grow to any arbitrary size. The main factor limiting size is the cost of the increasingly large amounts of food that are required, while the value of getting bigger is in increased safety from predators, more efficient heat retention, and the ability to kill prey. As filter feeders, baleen whales ignore the last one. And to survive in sub-zero temperatures, the size of a narwhal or beluga has proven to be enough. So the only factor baleen whales really concern themselves with is protection from predators. "Smaller" baleen whales like humpback or Greenland whales seem to be doing well enough already as surviving against predators is concerned, so that alone doesn't explain the much larger size of blue whales. Perhaps its the increased safety for their young which are already born massive and have almost nothing to fear.

If you want to justify a giant whale creature, then I think the only thing needed is some kind of predator that requires such a size to be fully safe.