Popcorn Biology: Avatar (2009)


The Smurfs get an upgrade.

Avatar, the highest grossing film of all time, adorated by legions of fanboys and hated by some intellectuals, especially directors who aren’t as rich as James Cameron. My verdict? In the middle: the story and characters are of course pretty bland and forgettable (and also a rip-off of Pochaontas, as everybody noticed) and the movie was probably too long, but the special effects are of course the most spectacular ever seen, and the action scenes are great. If you want a couple of hours of mindless, stupid, brightly coloured fun then Avatar is for you. Many also praise the supposedly very creative design of the creatures of this fantasy world; while some beasts are indeed cool to watch (especially the flying ones), to me many others seem just a lazy effort to make normal animals look weird only by adding a couple extra limbs and some featherish..things. Also, the color pattern of some animals seems to have been chosen pretty poorly (they look like they have taken part in some wild paintball battle). On the other hand, many people complained that the Na’vi were too human-like, but this didn’t bother me; yes, a weird and improbable example of extreme evolutionary convergence, but I can understand the decision to make the aliens look like us, since they’re the focus of the whole film and we have to empathize with them.And it’s not like the rest of Pandora is much more reality-based anyway.

Speaking of which, I digress. This is Popcorn Biology, I should criticize the biological aspects of this movie: a difficult task, as they are many, and many fanboys of the film have probably analyzed them in detail for years. I’ll do my best.

The first thing, the one that bothers me the most, is that for some reason humans can’t breath Pandora’s atmosphere. Which is incredibly odd since Pandora is largely covered in forests, made of trees with an uncanny resemblance to Earth’s trees (another extreme case of convergent evolution?). They’re green, ergo they have chlorophyll, ergo they do photosynthesis, ergo they produce oxygen. A lot of trees means a lot of oxygen, at least during the day.

Though, to be fair, it’s revealed that, in spite of their appearence, the trees of Pandora are quite different from ours, as they communicate with each other through electric and chemical signals, which means they have an equivalent of neurons, I guess. The trees and the animals of the planet are linked in a gigantic neural net, which of course is a concept inspired by James Lovelock’s Gaia “hypothesis”, which is less of an hypothesis and more of a vague metaphor made to capture the imagination of common people. I think that this SMBC cartoon explains my point perfectly.

Of course people tend to think of plants as a background, and focus on animals. What about the animals of Pandora? Well, as I’ve already said, they’re weirdly colored, as if the evolution on that planet didn’t give a fuck about camouflage, on the contrary of what happens here on Earth (no convergent evolution in this case?). Pandoran animals shown in the movie anyway are pretty big: maybe they don’t care about camouflage,, and on the other hand have evolved a system of communication based on colours and vision. The hypothesis is reinforced by the fact that most of them are also bioluminescent. On a side note, most Pandoran plants are bioluminescent too: do they need it to attract pollinators, or to lure the animals for some other reason? Who knows.

I’ve noticed that many animals on Pandora seem to have a respiratory system based on multiple tracheas that open directly on their chest. Maybe this is an adaptation to make possible their big size: enormous animal, especially erbivores, need to eat constantly enormous quantities of food; if they had to breath through the mouth (they’re not really technical tetrapods, so we’ll just assume that it’s possible that they can’t breath through the nose – do they even have a nose?) they would be forced to regularly interrupt their feeding not to die suffucated. This way, they can eat continuously without interruption, thus being a lot more efficient. It’s interesting to note that snakes have a similar adaptation to solve a different problem: they have to swallow the whole prey, so their mouth is occupied by food for relatively long periods of time; not to suffucate, their trachea is extended in their mouth, under the food, and it’s rigid so it stays open and able to breath even when the mouth is full.

The fact that most vertebrate animals of Pandora (although technically they’re not vertebrates, nor animals: they don’t share any common ancestor with animals, since they’re alien organisms) have six legs puzzles me. As I’ve said before, the creators of the movies designed them to be very similar to real animals (in this case tetrapods, especially mammals) in their shape and movement; so, since they move exactly like four legged animals, what’s the advantage of an additional pair of legs? The answer is: none. On the contrary, there are disadvantages: let’s put aside the fact that it would be more difficult ot coordinate them, every additional limb has a cost in term of energy and resources used to create and feed it: if it’s not useful (and in this case it’s not, since we’ve already estabilished that these six-legged aliens move in the exact same way of their four-legged counterparts on Earth), natural selection will make it “disappear”.

Speaking of legs, one of the nerdy criticisms about the human-like appearence of the Na’vi was that they only have two arms and two legs, while the rest of the fauna have 6 legs. I’ll defend Avatar on this one: first of all, this criticism sounds like “Most mammals have a tail, so humans should have a tail too to be considered mammals” (ironically, Na’vi do have a tail). Most important, the creators of the movie actually show a possible “evolutionary sequence” for the loss of limbs: a group of what are called “Prolemurs”, monkey-like creatures, still have sik legs, but the first two pairs are fused from the shoulder to the elbow. So in the Na’vi, other primate-like creatures, the fusion of the 4 arms to form 2 was complete. Maybe they evolved this way for the reason I explained in the previous paragraph, but it’s kind of strange, considering that they’re probably the only “vertebrates” on Pandora that could actually be advantaged by an extra pair of limbs, seeing how they have hands to grab and manipulate things. Oh, well.

Wow. That was long. Consider it a gift for the end of the year. I’m going to Rome for the holidays, so my blogging for the next seven days may be discontinuous to nonexistent (again). Happy new year folks, see ya in 2012.


Jerry Coyne: because one bio-blogger obsessed with penis jokes isn’t nearly enough

So, just when I was thinking that maybe the density of penis jokes on my blog was too high, super atheist blogger biologist Jerry Coyne makes me feel accepted with a post about animals with huge penises. I knew that the barnacles where the biggest considering the overall size of their bodies, but I somehow didn’t expect a killer whale to be so… let’s say manly. And the picture… god, that’s pretty graphic.

Friday’s Featured Organism: Salinella salve

Is it really an animal? Does it even exist?

The only species in the proposed animal phylum Monoblastozoa (or Celomesozoa), this little bag of ciliated cells seems to be a very primitive animal with anterior and posterior openings, but it doesn’t have real tissues, and has endonuclear mythosis (on the opposite of “real” animals). The best part? Nobody knows if it really exist, or existed. Found by J. Frenzel in the saltplans of Argentina in 1892 and known only by his drawings and descriptions, it has never been found since. Forget Bigfoot, Salinella salve is much cooler.

Friday’s Featured Organism: Hippobosca equina

The little fucker.

by Francesco Lami

This one will be longer than usual.

You know, unlike some people who say to like animals when they only like dogs, horses, cats and pets in general, when I say that I like animals, I mean it. Blue whale or jellyfish, whip scorpion or gastrotrich, they’re all fascinating and beautiful in their own way. Hell, I find fascinating and important even animals that are fucking annoying like mosquitoes or even plain dangerous like parasite nematodes. But if there’s something that I find very hard to like even a little bit, although it DOES have remarkable capabilities, that’s Hippobosca equina.

To Hippobosca equina, I say “Fuck you”.

The common english name for this critter is “forest fly”, and in fact the times I’ve encountered it I was in the woods. I didn’t know exactly what it was at the time: it was certainly a Diptera, and I suspected it was some kind of bloodsucker since it always returned stubbornly to bug me, no matter how hard I tried to drive it away. I discovered the family Hippoboscidae (louse flies) by chance navigating the internet, and it was clear that the mysterious fly was part of it, with its flattened body, long legs and that goddamn bloodsucking stylet. Discovering the exact species was easy because it turned out it was very common here in Italy. I read at Biodiversity in Focus that the reason they are flattened and have many setae on the thorax and the abdomen might be to hold on the feathers (and hair in this case, I guess) of their victims – seems a pretty good explanation to me, and the long, robust legs have probably the same function. I’ve never even been bitten by one of this animals, and they’re much less common than mosquitoes and other bloodsuckers, so why do I hate them so much? Because their ecological speciality is drive you insane. As I’ve already mentioned, they’re extremely stubborn; they take a hold on your skin and even if you force them away with your hand they come back in the exact same spot in less than half a second, like a goddamn living jet-powered boomerang. And that’s not the worst part – they’re indestructible. You simply can’t kill ’em because their exoskeleton is too fucking resilient. I tried with my bare hands, with a book, I even trapped one under a tissue and repeatedly smashed it with an heavy stone, but H. equina wasn’t even stunned, and continued to try to bite me. Mosquitoes and other insects have evolved not to be noticed while they bite you, and so they often succeed leaving you with unpleasant souvenirs; the forest fly just don’t give a fuck: it’s extremely easy to spot it and feel it on your skin, but it counts on the fact that it’s so relentless that you will soon be too tired to continue to resist it (and let’s not forget its near-immortality); and, since its favourite victims are horses and other animals that don’t have hands to continuously defend themselves, it surely works well.

Truth is charismatic too

Comic by “humon”, user of DeviantArt

By Francesco Lami

I post this strip made by an user of DeviantArt because it nails perfectly an extremely important concept: environmental conservation is not some kind of charity for some cute little defenseless creatures that need our help to survive. Envirinmental conservation is an act of self-conservation. We need clean water and air, food, medicines, a place to live, and without an healthy ecosystem we can kiss goodbye to all those things. I know that a lot of environmental organizations use the “charismatic megafauna” (big, widely known endangered animals) approach to earn donations because a lot of people is honestly convinced that “environmentalism” and “ecology” mean only “protection of an extremely limited number of very popular mammals and birds”, and I know that the aforementioned donations are then often used, as it should be, to protect entire ecosystems instead of just one species; but I think that we should try to use truth, and educate people about the real value of the biosphere: it’s not only incredibly beautiful, it’s VITAL. “Vital” in the sense of “necessary if you don’t want the human race to die out, bitch”.  And the most important organisms are often the least loved: insects, fungi, bacteria, worms, small vertebrates… Educating people about the real value of the environment, instead of just showing them only what they want to see (“OH! LOOK AT THE CUTE SEAL! LOOK AT THE CUTE SEAL! MAKE A DONATION FOR THE POOR LITTLE ORPHAN SEAL!) will earn us a lot more support, will show people to appreciate countless natural wonders that often are not even taken in consideration, and will help assure a brighter future for our terrible, awesome species.

And with this, I salute you, and go on holiday for a week. See ya later, bitches.