I don’t think I can put it off any longer. Episode 10 of the much-lauded TetZoo podcast – recorded just the other day and due to go live soon – made up my mind, as did the several science-themed articles about the movie published here at SciAm Blogs and at other science-based sites. Put simply: I have to blog about Pacific Rim.

I’ve seen the movie twice now (once in IMAX) and have spent a lot of time talking about it online and IRL. So, in the spirit of the Tet Zoo article on Avatar, here are assorted thoughts and observations on the movie, focusing on the Kaiju. First things first: SPOILER ALERT. You have been warned.

As usual, I’m not going to pretend for a minute that Pacific Rim is a particularly special movie when it comes to plot, theme, or characters. Personally, I’ve simply enjoyed it as a massive, CG-laden romp based around giant Kaiju* and huge humanoid robots and, indeed, there are several major weaknesses, flaws and absurdities throughout both the movie and the Pacific Rim universe as a whole. At the risk of repeating the opinion already notoriously proffered by my colleague and friend John Conway, the outstanding near-absence of women from the Pacific Rim universe is weird and inappropriate. We see stuff that doesn’t make much sense in terms of materials science, engineering, physics or chemistry, and there are sheer impossibilities like the bit where Gipsy Danger glows red while falling through the atmosphere before landing safely, fully functional and with intact humans onboard.

* Kaiju is a generic term used for any sort of monster, including outlandish ones that are mechanical or floral in nature. In the Pacific Rim universe, the term Kaiju is used specifically for a class of gigantic alien creatures that, via a portal in the Pacific called The Breach, are invading our planet from a base in the Anteverse.



While writing the article you’re reading now, note that I don’t have the movie, nor its script, to hand, thus meaning that some of the details are only half-remembered and quite plausibly inaccurate. Furthermore, I haven’t yet seen or read the prequel graphic novel Pacific Rim: Tales From Year Zero; a shame since it might provide abundant background info on Kaiju origins and biology.

Ah, those good old stereotypical scientists! Why, Hollywood, why!?

Before we get to the Kaiju, I want to say a few things about the two scientists in the movie, Newton Geiszler and Hermann Gottlieb. While – based on the movie alone – we don’t know anything about the background to the involvement of either person with the Pan Pacific Defense Corps (if this term is new to you, it’s used throughout the movie: you often see PPDC badges on uniforms and in buildings), I think it’s reasonable to assume that both are meant to be brilliant and capable experts in Kaiju biology, and hence in biology, physiology, biochemistry and so on in general. It’s therefore weird to hear either of them say dumb things that don’t ring true. Yeah yeah, it’s only a movie but… come on Hollywood, why don’t you ever talk to real scientists and get this crap corrected?! It's very easy to do this sort of thing, it adds extra depth and detail to the movie, and it makes fan-boys and girls love and appreciate you all the more.



So, Newton compares the “second” Kaiju brain to the mythical “second brain” of dinosaurs. I was initially happy to let this go, but given what I just said about him presumably being an all-round biology whizz, it’s hard to be so forgiving, given that no self-respecting expert would ever say this. Yeah, ok, the paravertebral ganglia and so on allow a degree of autonomy as goes various actions performed by the body, but it remains downright wrong to speak of animals having a ‘brain’ in the sacral region. For further discussion of the whole 'dinosaurs had a second brain' thang, see Matt Wedel's article on the issue over at SV-POW! (Matt was quote-mined by a TV company, and there was much appropriate wailing and gnashing of teeth).



In another part of the movie, Newton explains why he thinks that the Kaiju are clones, but why did they have him refer specifically to DNA? Err, hell-o, we’re talking about bio-engineered creatures from another dimension (or universe) here: why would any heritable information be encoded in a molecule with the same composition as DNA? It wouldn’t, it would be something else. Movie people should know this; it would be no trouble to have Newton use some other acronym and explain in passing that that given molecule is the one that serves a DNA-like role. By the way, if Kaiju are bio-engineered we might speculate that they wouldn’t have a DNA homologue at all. Hmm.

There’s a second issue. Newton is obviously meant to be a fairly normal person but the idea behind his character is that he’s gotten himself all tatted-up in order to get away from a nerdish stereotype that he somehow dislikes or is afraid of. Err, excuse me? A self-professed Kaiju uber-nerd who dislikes the idea of being a nerd? Really? Getting tats of your favourite beasts is fine and I’m all for that, but I resent the idea that nerds dislike being nerds and strive to turn into other things. Hell no, puh-leez, norms are boring, sheep-like things that lead unfulfilled lives of tedium.



Things are much worse when we think about the other scientist character, Hermann Gottlieb. He’s a bumbling, upper class loner who’s socially incapable and has rarely, if ever, left his laboratory or secret lair or castle or whatever (though... backstory stuff from elsewhere in-canon, he's in a full-time relationship and his partner/wife has a baby on the way). This stereotype – the socially inept, freak scientist – is damaging and boring, but also full of bullshit since anyone who’s as good as Hermann’s meant to be, or has gotten as far as he’s meant to have done, would – in actuality – be socially skilled, political and unusually outgoing. So, bad job Pacific Rim, you let the side down. This kinda grates more that it should actually because sci-fi movie people really are on the 'same side' as scientists: they're dedicated visionaries, deeply immersed in the awesomitude of the stuff they're interested in, striving to share the wonders of their world and ideas with the masses. Annoying and stereotypical portrayals of scientists are bad for us all. Maybe I'm making too big an issue of this, but such portrayals look like propaganda for the conservative right ("look, scientists are all freaks who don't live in the real world!").

What the Precursors did, and what the Precursors are doing



Kaiju are not just animals, they’re manufactured, cloned bioweapons that have been engineered by an alien culture, sent through a portal in order to kill as many humans as possible and make huge areas uninhabitable. The alien overlords – the vaguely arthropod-like, 3-to-4-m-tall Precursors – aim to rid a planet of its pesky natives (in this case, humans) before moving in themselves (an MO similar to that practised by the hostile aliens in Independence Day). We know that Precursors have tried this before: the wording is ambiguous and I don’t remember it exactly (it comes from Newton’s drift with the brainstem), but it’s implied that they tried this in the Mesozoic with unsuccessful results (were they implicated in the extinction of non-avialan dinosaurs? Or is it that they created dinosaurs? I really hope the latter isn’t part of the storyline – that would be uberlame on a Prometheus-like level).



On 21st century Earth, the polluted, CO2-rich atmosphere, acidic oceans and so on have apparently made conditions more ideal for the Precursors, so now is time to try again. By the way: has Precursor culture really persisted for tens of millions of years (implied by the reference to invasion effort # 1 occurring in the Mesozoic), or is The Breach a portal through time as well as space? I don’t think we know.

Concept art shows that Kaiju are grown by the Precursors in biomechanical cages of a sort. During Newton’s drift, we see a few flashes hinting at the idea that the Kaiju are surgically modified by the Precursors and treated in a brutal, hostile manner perhaps involving pain and general nastiness: they are not treated humanely. We have no idea (so far as I know) as to the sentience or otherwise of the Kaiju, but this treatment raises questions about that issue. More on that in a moment.

We also know that the Kaiju are clones. If this is true, why the massive variation in phenotype? All the Kaiju we see – I assume this goes for all the Kaiju (contra the concept image shown above) – are absolutely different in external anatomy. How can this be so? I don’t know if the answer is revealed in-canon, but we might speculate that Kaiju are surgically modified as they grow, that the Precursors are skilled at manipulating the anatomy of test-tube embryos, or that epigenetic mechanisms somehow produce different Kaiju castes, morphs, or even operate differently for every single individual. My bet is that embryological design of some sort is at play, since the Kaiju seem to become progressively more weaponised throughout their war with humans (they’re successively improved, somewhat like the Omnidroids created by Syndrome in Pixar’s The Incredibles). Leatherback – a Category IV – is even kitted out with an EMP-emitting organ on its back, a structure that the Precursors have apparently built into the Kaiju’s design to deal with the Jaeger response.



Are the Kaiju just automatons that smash and destroy once they get through The Breach? Well, we’re told that they operate “under orders”, that they're connected via “hive mind”, and that some are more intelligent than others (Slattern, the only Category V we see, is said to be the smartest so far). Leatherback even uses a tool (a crane) in its fight with Gipsy Danger, plus Leatherback and Otachi – and Scunner, Slattern and Raiju in the big fight at the end – are supposed to be working together as teams when battling with Jaegers. These aspects of the story either imply that Kaiju are smart (and sentient?), or that they’re controlled by the Precursors. Of course, if the Kaiju are smart and sentient perhaps we should feel sorry for them and wonder why they’re ok with being treated as they are; is it that they've been beaten into submission, like trained dancing bears? Could there be a Kaiju revolution one day where they escape bondage and get to live free lives?

On the issue of sentience and "hive mind", what exactly was Otachi trying to achieve by finding Newton? Did Otachi think that Newton was another Kaiju, did the Kaiju and/or the Precursors now need or want Newton because of his mind-link with their culture, or what? Thoughts appreciated.



We’re told (and shown) that Kaiju are toxic: their tissues, secretions and breath are toxic, at least some of them can discharge insanely powerful acids (Otachi pretty much melts a building as well as the armour of the Russian Jaeger Cherno Alpha), and – even when they’re killed – their blood (‘Kaiju Blue’) pollutes the land, water and air around an attack site and makes it uninhabitable (or does it? Read on). Remember that numerous Kaiju have been attacking the cities of the Pacific region for more than a decade by the end of the movie, meaning that many cities have been attacked and many Kaiju have been killed.



In my opinion then, we should rightly imagine huge areas around the Pacific where hundreds of thousands to millions of people have been killed, and huge tracts of land been made uninhabitable, due to numerous Kaiju attacks. I feel that it was all too easy to forget this by the end of the movie: they should have reminded us that getting rid of the Kaiju menace really was a matter of ‘extinction or annihilation’, since the later part of the film otherwise made it feel as if life was carrying on as normal, bar the occasional Kaiju vs Jaeger battle going on in the background.

Am I right though? Were Kaiju really making the edges of the Pacific uninhabitable? There’s a plot-hole here. Remember the skull-like building, serving as a Hong Kong temple for Kaiju worshippers and shown during one of the scenes where Newton talks to Hannibal Chau? Turns out this really is a skull, specifically of Reckoner, a Kaiju that attacked in 2016. Yet, despite the Reckoner’s tissues doing what a Kaiju’s tissues do, the area has turned more or less back to normal within a decade (the film is set in 2025). That’s not right – they should have stuck with the idea that Kaiju kill an area for centuries.

Kaiju appearance and anatomy



The creature designs in Pacific Rim are great: we owe them to the amazing Wayne Barlowe. In appearance, Kaiju combine a vaguely humanoid profile (note that virtually all are shown at some point standing bipedally, the thoracic region being held vertically or nearly so) with various features being reminiscent of assorted sharks, reptiles and other animals. Of course, it’s difficult to create an imaginary creature and not have it be at least somewhat reminiscent of a real creature, so while there’s obvious novelty and cleverness in the Kaiju designs, several of them enough recall real creatures that they look to be based on them. Knifehead has a head reminiscent of a goblin shark’s, Onibaba is a huge crustacean, Otachi has pterosaur-like wings, Leatherback is gorilla-shaped, Raiju looks like a super-powered cross between a crocodile and a pangolin, and Slattern has a hammerhead… head.



I wish we had better views of Slattern. It’s the only Category V we see in the movie, but the fight scenes and fast-paced action mean that we never get a clear look at the whole creature. It has a tripartite, weaponised tail, a few tentacles, thick, rugose armour and sharp triangular spines projecting from the shoulder and back. It's also difficult to appreciate Slattern's size - it towers over the Kaiju we see earlier in the movie.



Having mentioned Otachi, I noted even when the trailers were all we had to go on that it seems to have a Clover-esque look, by which I mean that it’s quadrupedal and has slender, sprawling forelimbs. We now know the reason for this: Otachi is partially bat- or pterosaur-inspired, with tightly furled wing membranes that are stowed away on the sides of the forelimbs. During Otachi’s flight, we see that the wing membranes connect to the sides of the body, not to the hindlimbs. They must be composed of some insanely thick, resistant tissue, but just how this withstands flapping without breaking to bits is unknown. Otachi also has a prehensile tail with a tri-pronged grabbing organ at its tip, a lower jaw that can be split apart along its midline, and a bioluminescent, lure-like tongue (or tongue-like organ) covered in glowing bulbs. Deepsea fish, anglerfish in particular, come to mind.



What do we know about Kaiju internal anatomy? We know that they have bones or bone homologues since we see skeletal remains (including skulls and what look like vertebrae) on a few occasions in the movie, and we also see what look like guts – plus we’re told that Kaiju produce shit, in which case they must eat and have a functional digestive system.

Massive, strongly curved hand claws present on several Kaiju look semi-inspired by those of big-clawed theropod dinosaurs like Spinosaurus (though I don't see any inward-facing palms on the Kaiju, the normal condition for theropods). Then again, how are big, curved claws on prehensile hands gonna look if not like that?



While the Kaiju are diverse in form and certainly in head shape, there are a few anatomical features that hint at the idea of some sort of relatedness. Look at the forelimbs of Scunner, Slattern and Knifehead: in all three, it seems that the primary forelimbs represent fusion between two pairs of original, slimmer limbs, since there’s an oval-shaped gap in the lower arm. Concept art shows that this was also originally true for Karloff (a Kaiju that attacks Vancouver), but it looks different in the film (and in Tales From Year Zero), with slim forelimbs and slender, pointy-clawed fingers. Karloff is seen briefly in the prologue (if you look at Karloff’s head, I think it’s pretty obvious why it has the name that it does). Anyway, this forelimb feature reminds me of a similar gap seen in the primate-like Prolemuris creatures from Avatar.

Actually, I’m not sold on the idea that the Kaiju ‘arm gap’ represents fusion at all – it might just be a neat-looking (and alien) gap that the designers incorporated for the hell of it (I note that a similar gap in present on the tail of the concept version of Karloff). Furthermore, the idea of arm fusion is obviously contingent on the existence of evolution in Kaiju, and if the Kaiju are designed for a job, they most likely are not breeding and evolving.



But – hold on, Otachi is pregnant and produces an offspring (who stayed after the credits started rolling?). Furthermore, the baby was a baby Otachi, not a generic Kaiju that looked different from its mother, so Kaiju forms appear to breed true. What could this mean? Does it mean that at least some Kaiju are allowed to roam and breed before coming through The Breach? Does it mean that Kaiju are parthenogenetic and might pop out babies at any time? Does it mean that Otachi is a special case? Of course, I don’t know.

Huge blade-like structures, used as weapons in combat and clearly good at breaking into Jaeger hulls when opportunity allows, are shared by the heads of several Kaiju. Trespasser has an axe-like blade on top of its head, Knifehead has a blade-like snout, Mutavore has an aft-curving chin blade and backswept cranial horn, Scunner has paired lateral horns, and so on. Each of the Kaiju are really distinct in head form, however. I drew little sketches because I thought I might be able to link them in a sort of pseudo-phylogeny, but… no. Here’s the result… note that the tree is unrooted, for obvious reasons I think.



Bioluminescence is also a constant theme across the Kaiju; used, I assume, because it looks cool, especially with so many of the Kaiju being shown at night or in dark water. If we imagine movies to be ‘related’ to one another by way of their designers, studios and inspirations, this all seems like an obvious nod to Avatar. Indeed, I really like the idea that the creatures, plants and ecosystem of Pandora are designed by a failing but industrially adept Na’vi culture that have built bioluminescence into everything such that the forests of Pandora are illuminated during the night. If the bioluminescence in Avatar is anything to do with bio-engineering, and given that we know that the bioluminescence in the Kaiju of Pacific Rim is the result of bio-engineering, has this become – or will it become – a new motif indicating the fact that a movie creature has been bio-engineered? Keep an eye out for it in other movies.



On the subject of luminescence, what’s with the fact that Trespasser’s maw glows during the attack on San Francisco? That opening scene was extremely badass but I’m struggling to work out why a creature would look like it had a bonfire going on in its mouth.



Raiju seemingly has a bony, armour-plated head, but what we’re actually seeing is three separate mobile plates that surround the genuine head, protected in the centre but exposed when the plates are opened. Seeing as the real head is vulnerable and (so far as I’ve been able to tell) doesn’t have any special function as a weapon, exposing the head at any point during combat doesn’t seem particular wise, but what the hey.

To the future. Come on, Hollywood, do it right, for all our sakes...

I frequently run against the opinion that you’re over-analysing movies if you think too hard about stuff like the origins, anatomy and evolution of creatures like the Kaiju of Pacific Rim. But, to somebody interested in evolution and biology, questions like those raised above are unavoidable – we have to suspend disbelief when watching a film as outlandish and OTT as Pacific Rim, for sure, but how can we immerse ourselves in the universe of the film without asking those kinds of questions? We want to know; we might even need to know, and when there aren’t any answers because film-makers are too lame or too dumb to think them up (Lost, the ending of Tim Burton’s Planet of the Apes), the film has failed. I don’t think the people behind Pacific Rim are in that category: I bet the answers are there, and it might even be possible to find them out. And thus I must seek out the Pacific Rim books.

And so, time to end. Sequel? Well, maybe yes according to del Toro. It all depends on how well the movie does in Japan, where it opens July 31st.