Avatar 2: The Way of Water II: whales, gill mantles, corals...

In the previous post on 'The Way of Water (TWOW) I discussed the skimwing, and had to conclude that it couldn’t work as an enlarged flying fish because of scaling effects. Simply said, they overdid it and made it impossibly large. Making animals too large is a recurring theme on his blog. The underlying reason is probably that the effects of scaling on mass and weight are not intuitive at all. Speaking for myself, even after years of considering animal size, I still sit back often and think that 'That is too much and can’t be right…'. For example, would you have guessed than making a man twice his original height of 1.75 meter would increase his weight from 80 kg to a staggering 1440 kg?    
 

But anyway, today's species will not involve any calculations at all. Let's have a look. 

 

Click to enlarge; copyright 20th century studios

The tulkun
The tulkun looks so much like a whale that we will just call it that here. To quote from the book ‘The Art of Avatar TWOW' by Tara Bennett: “… it’s very much written like a whale and functions like a whale. But how whalelike do you make it?” 

Click to enlarge; copyright 20th century studios

Well, apparently some early designs were not whale-like enough, and the book offers some glimpses what might have been. Here's one. I would have preferred something more alien, but the audience would probably not have connected the resulting much more alien shapes  with the emotions associated with whales on Earth (I am referring to the sympathy and enthusiasm for whales in most of the West, not the sentiment "Let's have a big whale steak!"). The Avatar film makers obviously intended to evoke whale enthusiasm. I like whales too, but felt that the film makers overdid it when tapping into sympathy towards whales. This particular whale species happens to have a clear yellow fluid in its head that stops human ageing, serving as background to have a scene in which villains enthusiastically harpoon the whales to get that mystery substance.

Do we need to discuss the plausibility of an alien biochemistry producing a substance for its own good that by an apparent coincidence also just happens to stop human ageing? Human ageing does not appear to be a process depending on just one simple biochemical trigger (although that cannot be dismissed with complete certainty). If there would be one, you can expect a massive effort to identify the substance, and shortly afterwards it could be manufactured on Earth simply and cheaply. Let's also not discuss how you would find out that some fluid inside an alien animal's head stops human ageing. Did someone stumble upon this liquid and thought "Let's just see what happens if I inject myself with this"?

The tulkun is supposed to be extremely intelligent: it appears capable of understanding the spoken language of a completely different species. That's quite something! Humans take a very long time to learn another human language, but maybe we are just more stupid than Pandoran whales. But even the brightest whale could only extract meaning from spoken words after gathering a massive amount of data to correlate specific sounds with objects, questions, tenses, nouns, verbs, etc. etc. Another big question is how and why intelligence would evolve in such a being. I personally do not think that you need hands or something similar to develop intelligence. I always rather liked the view that social interactions played an important role in evolving human intelligence (including gossiping), and perhaps such interactions were important for these whales too.  

Anyway, the tulkun looks like an Earth whale. So much so that I do not doubt it would function well as an organism, except for one thing: why is it not streamlined? It can obviously move fast, so streamlining is not a luxury, but a necessity. The animal has a rough texture with  grooves and ridges. There is also its headgear that doesn’t help streamlining either. Are these details there only there to make us think that it’s a whale, but not one of ours? If so, I am a bit disappointed. Streamlining fast aquatic animals should be compulsory to achieve some biological believability.

 

Click to enlarge; copyright 20th century studios

The gill mantle
The gill mantle is an animal that latches onto the Metkayina (partially aquatic Na’avi), meaning Pandora’s native humanoids. The gill mantle allows them to breathe underwater. That is quite a feat. If the Matkayina’s metabolism is like that of Earth mammals, they need lots of oxygen and a way to get rid of CO2 (and, seeing they can dive deeply, ways to deal with pressure to avoid the bends). The gill mantle can do all that, it seems, which is quite a feat. The problem here is that gas exchange needs a very large area, usually obtained by folding the gas exchange surfaces right down to the microscopic level. For instance, estimates of the total area of human lungs amount to 100 square meters. But the mantle looks smooth; I don’t see any kind of subdivision offering the requested area, nor does it transparent nature suggest that the mantle houses the rather considerable blood flow needed: in humans, the same amount of blood flows through the lungs as through the rest of the body, meaning some 4 litres per minute.
But the real tricky question is why any animal would evolve such a feature? How does it benefit from this ability and how did its evolution start? 

Click to enlarge; copyright 20th century studios

Coral
You might be surprised at my choice, but the image in the TWOW book that caught my attention longer than all other ones was not one showing a big spectacular animal, but a coral fan concept by Jonathan Bach. Here it is (page 191). It is very well wrought. The connections between its branches caught my eye.  The ends of the arches are merged, forming a complete connected structure. This means that the arches do not form the typical branching structure familiar to Earth life, from lungs to corals and oak trees, but a net. The easiest way to form a biological net is probably to start with a sheet, or a series of planes in 3D space, and then to make holes in it, leaving just the arches. However, plants and Earth corals grow branches with ends, and branch ends do not typically merge if they touch one another. There is some evidence that Earth trees can do that though, and I designed Furahan thorn shrubs that did so, resulting in a truly impregnable wall of thorns. I have not used that design yet, because I felt that little hooks would work just as well and would not require an organism to open its tissues to the outside world. 

Click to enlarge; copyright 20th century studios

The ilu
I am not yet certain what to think about the ilu yet. It looks a bit like a plesiosaur with a small head and a long neck. But whereas plesiosaurs have slender fairly stiff fins with rounded narrow tips, as do turtles, seals, and mosasaurs, the ilu has very long somewhat floppy fins that appear to get broader towards their ends. Are there Earth analogues for such a design? If not, is there a good reason for that? I'll have to think more on that, so perhaps there will be third post on TWOW.

So, what did I think of the animals in TWOW? I felt the same as I did about the first film in the series: the images were very pretty. I will watch the film several times and enjoy it every time. Still, I again felt a bit disappointed about the lack of biological plausibility. Would the audience really object to more plausible or more alien shapes?