When you’ve watched the original Star Wars as much as I have, and you have a propensity towards overthinking as much as I have, the thought can creep in unbidden:
What do wild Banthas eat?
I mean, look at the size of these bastards:
It looks like it should be an herbivore, but the desert world of Tatooine seems rather devoid of even the smallest grasses, much less trees and shrubs. For that matter, they’ve obviously been around long enough to become integral to the culture of the native Sand People, and yet if they are also native to Tatooine, what’s with all the hair? They look better suited to somewhere like Hoth. Was Tatooine once a much cooler and more floral place prior to some undefined climate cataclysm? If so, it seems like the Bantha should have been one of the creatures that died out in the aftermath of that.
The short answer to all this is, “Presenting a valid planetary ecosystem isn’t the point of Star Wars. Shut up and enjoy the movie.” It’s only because of the longevity and popularity of the film anyone might even grow to care, because it’s a good enough piece of entertainment to cook along and carry your immersion right through any logic gaps. I’m sure Banthas in the original production had no explanation beyond Rule of Cool, although that hasn’t stopped people from attempting more reasoned analyses in the decades since. Your mileage may vary on whether such reasonings deepen your understanding or are just so much unnecessary Voodoo Shark, a la the “midichlorians” concept introduced and then summarily abandoned after The Phantom Menace. Turns out most of us really didn’t give a crap how The Force might work from a biological standpoint and just wanted to see dudes shoot lightning and throw stuff.
Anyhow, back to ecosystems. Complicated stuff. Mess with any of it and you’re pretty much messing with all of it, and it’s difficult for even professional ecologists to predict the outcome, much less your average poor writer of speculative fiction. Mind you there are certain things that should seem obvious given even a little thought, like what should happen as a result of Stephenie Meyer deciding that the vampires of Twilight kill and feed only on apex predators of Washington state. I’m sure this is a conceit no doubt meant to make them seem nice since they not only stay away from humans but also only eat nasty, nasty mountain lions rather than cute little Bambi deer, and yet all I can think of is how the forests of Forks should be far more barren after several years of this and the resulting deersplosion it would cause. That doesn’t happen because it’s not important. Unfortunately, Twilight isn’t a good enough story for me to ignore it.
Now zombies… that’s a darn big change to introduce to an ecosystem. Talk about an invasive species! Your average zombie setting doesn’t touch on such things much, especially if it’s just an “apocalypse as it happens” scenario. In general the zombie phenomenon is limited strictly to humans, or perhaps humans and one other species (often also the plague vector) like in Black Sheep or Dead Meat. I’ve gone so far as to include the entire spectrum of Class Mammalia in my scope — which is huge, and has instantly ignited speculation on such matters as the zombie platypus and the zombie orca.
This has actually been my scope since the beginning, but I’d be lying if I didn’t admit that it’s intimidating to consider all the implications, and it’s scary to officially “pull the trigger” and finally confirm it in the comic last week. How does the existence of zombie whales and seals affect the fishing industry? What about the ubiquitous rat? What would Forks look like after the mountain lions and deer are either wiped out or become the living dead? Sure, your usual zombie flick can cheerfully ignore these questions, but a big part of my setting is imagining a new equilibrium that’s settled in after a generation of crazy upheaval.
My sanity is preserved here by keeping the story focused for the most part on a very small setting with people who don’t necessarily care about the larger implications of how the world has changed, beyond what has affected them personally. My horse likes meat, but it’s still basically a horse, and its bite won’t make me a zombie; Suzie actually rattled off a ton of exposition in those few sentences. You could assume that what she says is specific to her case, but given the blasé attitude displayed towards a world full of things like zombified prairie dogs, I feel it’s pretty clear that other animals operate along the same lines. Zombie rats that could zombify people would be a nightmare, although it’s useful to keep in mind that the historical Black Death was spread mostly by their fleas and not the rats themselves. Beavers are considered a keystone species of their environment (I haven’t seen the Zombeavers movie but I’m going to hazard a guess they didn’t go into environmental impact), but the idea of removing them from the equation is still less of a potential upheaval than if all the honeybees on Earth started craving flesh instead of nectar.
Also, it’s an assumption to conclude that just because all mammals can become zombies means all mammals have become zombies. There’s another important bit of how all this works that I still haven’t spelled out yet, which is important for me because it lessens the scale of change, particularly where things like ocean-dwelling mammals are concerned. Does it make sense from a scientific standpoint? Maybe not, but it’s consistent with the vision we’ve presented so far and makes at least enough sense in context I like to think that if and when we do confirm it we’ll get a pass. Sometimes, like with the Bantha and The Force, it’s better unexplained. But it’s important we know The Force has its limits (no matter what Yoda says) so we know how it shapes the narrative, and that’s the real ecosystem a writer should first and foremost be concerned with: the ecosystem of the story.