From Stones to Sex: Making Realistic Animals in Fiction

This article on writing realistic fictional animals is part of the Science in Sci-fi, Fact in Fantasy blog series. Each week, we tackle medical or technical aspects of science fiction or a historical / world-building topic of fantasy with input from an expert. Please join the mailing list to be notified every time new content is posted.

The Expert: Adam Gaylord

Adam Gaylord (@AuthorGaylord) has a BS in Zoology, a Masters in Wildlife Management, and over two decades in the field working around the U.S. with sea turtles, jumping mice, elk, eagles, and beaver, just to name a few. He’s also an author with short stories places like Diabolical Plots, the Cast of Wonders podcast, and Unidentified Funny Objects 9. His first novel came out in 2015 and his new novella, The Pheeworker’s Oath, is due out from Mirror World Publishing in 2024.

From Stones to Sex: Making Your Fictional Animals Less Fictional

On the whole, I tend to like animals better than people. They’re generally pretty quiet (except for howler monkeys) and rarely lie. The only time I’ve been threatened by an animal, a big momma feral pig, I was able to scare her away by waving my hands and shouting in a bad Scottish accent. That might work on a drunk at the bar, but I doubt it. So, needless to say, I spend a lot of time watching, reading about, and pondering our furry or feathered neighbors. And I read a lot of fiction, mostly sci-fi and fantasy. Both genres include unearthly beasts. The more the better, I say. But what makes a fictional animal really come alive on the page? Here are some things to keep in mind when crafting your own crazy critters.

The Cornerstone: Evolution

Biology is the study of living things and quite simply, evolution is the cornerstone of biology. As evolutionary biologist Theodosius Dobzhansky (1900-1975) once said “Nothing in biology makes sense except in the light of evolution.” And the single most important thing to make your fictional animals make sense is to consider them in an evolutionary framework.

“But evolution’s too complicated and takes place over millions of years and my uncle Carl says it’s a government conspiracy to get us to buy foreign cars.”

First off, Carl owes me money. Don’t trust that guy. Second, evolution isn’t that complicated! It’s all about traits (i.e. genes) proliferating in a population over time. For example, more individuals with a gene for denser fur will survive harsh winters to breed, thus more individuals in the next generation will have that gene and over time and fur density will increase (as will the gene). Given enough time, and some other changes, animals in the colder range might change enough that they’re no longer the same species as those in the warmer range. Boom! Evolution! But that’s just one example. Evidence of evolution is all around us! You don’t need a Darwin tattoo (like me) to work some into your story. You just need to understand some of the basic mechanisms behind the process.

It’s All About Habitat

Your hero crash lands on a desolate, frozen planet, his hair only slightly tussled and a single cut highlighting his already prominent cheekbones, only for a gigantic lizard creature to burst through the ice and give chase on its six gangly legs.

On the big screen, this might work. The action might be too fast and furious for someone to point out that a huge lanky critter has huge amounts of surface area (skin) exposed to the elements meaning it’s losing lots of heat, which on an ice planet is probably a big deal and a terrible disadvantage from an evolutionary standpoint.

Look at animals from the ice age. A mammoth is very round. That’s because spheres have the lowest surface area to volume ratio of any shape which is very advantageous for retaining heat. Gangly mammoths wouldn’t survive to reproduce, unless gangly-ness conveyed some other, greater evolutionary advantage. This giant lizard creature doesn’t fit its environment and a careful reader might notice and noticing means the reader is taken out of the story. No good.

Think about our world and where animals live. Think about what traits they have and how those trails fit their environment. Then, take what you see and make sure your animals fit their habitat.

Energy as Currency

Life isn’t simple enough to break down into an easily understandable equation very often. That having been said, living things need energy, and if energy input (food, sunlight, life force sucked out of unsuspecting tinder dates, etc.) is less than the energy output (the calories/life force/whatever) a being needs to do what they do, then that being will starve. Pretty simple.

In the example above, bursting through ice and chasing prey is enormously energetically expensive. If we’re on a barren ball of ice, how is this creature getting enough meat to meet its energy demands? How is it not using crazy amounts of energy to stay warm? Could that animal possibly exist on this planet?

Probably not.

“But I need a beasty for my story and I want it to be on an ice planet because ice is a metaphor for my ex-wife!’

Fine, then think about what makes sense. You need a big beast, then maybe come up with some kind of ambush predator that can stay down in its cozy den until an unsuspecting hunk of man meat walks by and then WHAMO right in the kisser. But it would need to stay close to its den or it would use too much energy or freeze. Think it through.

Form Follows Function

You love flying squirrels. Don’t deny it. They’re too cute not to love. You couldn’t hate them if you tried. But what you might not realize is they’re a great example of a basic guideline for crafting creatures: form follows function. The patagium, that skin that stretches from a flying squirrel’s front to back legs, lets it guide from tree to tree. It’s there because it provides a useful function.

Don’t give your fictional animals traits for no good reason. Your beast is slimy? Why? It has tusks? Why? Just to look cool? If you can’t come up with a simple answer, then consider swapping slime or tusks for a trait/adaptation that makes sense given the animal’s habitat and behavior.

Survival or Propagation

You might read this and say, “This guy is obviously very smart and also handsome, but what about giant antlers that take a ton of energy to grow? What about long tail feathers that make it hard to fly? What about brightly colored scales that draw the attention of predators?”

Well, I tip my hat to you my perceptive friend. Until now, we’ve been talking about natural selection. You know, the one Darwin wrote about? It says that traits that benefit an organism’s *survival* will be passed on to the next generation and will proliferate in a population. But some traits don’t help an animal survive. Some traits are just there to be SEXY.

A bird of paradise’s dance moves (look it up) don’t help it survive, but it does make the other sex want to take a ride on the love train. That’s sexual selection: traits that are passed on and increase in a population because they attract the opposite sex.

In Summary: Justify Animal Form with Function

So, what does that mean for you? First, learn to dance. Then, maybe your beast has brightly colored flaps of skin hanging from its face. Why? To funnel smells to its olfactory sensory organs? But it eats eggs, which aren’t known for being smelly until nobody wants to eat them. Ah, it’s because bright skin flaps drive the fellas crazy with desire. That’s the type of detail that can bring a fictional critter, and a story, to life.

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