Designing Alien Worlds - Part II
Month 6, Week 1, Episode #7
While the last post I had was focused on the landscape and general geography of a world you design, this one focuses on the evolution and design of local life forms. In short, this about the Ecology and how it dictates the world.
II.) Designing the Ecology.
We've got an geography, now to add the plants, animals, microbes, and other life which makes the world go round.
One of the many surprisingly good bits of science in the game Mass Effect is the concept of biochemical barriers. In the game these barriers are primarily arranged around chirality. The turians and quarians in the game have a different chirality to their biochemistry making food for them toxic for humans and other 'levo' based life forms, and our food toxic to them.
Just a slight difference can cause such seperation, but that's not the only difference that is possible in a creature's evolution. The very moleculer basis for life could be very different, and it's possible for life to develop along multiple lines on one world, thus having several co-existing ecologies existing side by side, only competing for space and sunlight. Symbiotic relationships may be possible as well, leaving such worlds extremely fertile grounds for the writer.
1.) Carbon, Sulfur, Silicon, or other?
The first decision you must make is to decide what will be the basic chemical reactions upon which your life forms will be based. The most common of which, in human experience, are carbon-based life forms. Carbon-based life forms utilize how carbon can form complex chains to create protiens and other hydrocarbons. However, recent discoveries show that carbon-based life is not the only form of life on this planet.
Studies and expeditions to the deep sea vents have revealed that there is life on our own planet that utilize sulfur in their biochemistry, and while most of this forms of life only utilize sulfur for food from the enviroment, sulfur is capable of forming long-chain molecules that could act like proteins, making sulfur a viable alternative to carbon.
The most commonly suggested alternative to carbon-based life is silicon. As silicon shares many properties with carbon, but as a metal has several other properties. Any life that evolves from silicon long molecules could be vastly different than that which evolved on earth, and perhaps require what we would consider to be an 'extreme' enviroment.
Once evolution has started on a world with the rise of autotrophs (catipulting a world into the 'Garden stage') it's only a matter of time before organisms adapt to use the autotrophs as a source of energy (by eating them). This results in a food chain of sorts, as hetertrophs develop which prey upon the autotrophs and eventually each other.
B.) Create a Food Chain.
The food chain is probably the single most basic way to give body to a terrestrial ecology. Generally, any intelligent life on a world ends up at the top of the food chain, with an autotroph or plant of some sort at the bottom. There are, of course, exceptions. When evolution has provided super-predators capable of bringing down intelligent beings, or perhaps intelligent life which are plants.
Among the many storylines that I've explored a bit over the years for use in the Ambrose Chronicles stories, one was of the two main characters stranded on an inhabitated planet trying to survive until rescue.
The planet would be a classic terrestrial world orbiting a red dwarf star. It would be tidally locked, thus making it so that only one side of the world faced the sun at any time, thus making the twilight zones the most habitable, thus making the two stranded midshipmen sleep in shifts and watches as there is no day and no night.
Then there was the local wildlife, which I had to design from the ground up...
1.) Designing the Foundation.
If one were to make a food chain for the vast majority of ecological enviroments on earth, two autotrophs would quickly emerge as the most common foundation for life's evolution: Grass and Plankton. So, the first step is to create an autotroph that fits the local conditions. In my example, I have a red dwarf star. As I already mentioned, the color of the star will most likely effect the normal color of the vegetation (Earth's G-type star = Green vegetation, Red star = Red vegetation).
Here, a decent understanding of evolution on Earth can be extremely helpful. Before there was grass on land, the primary plant that covered most of the ground were ferns... I've often found that knowing things like that can be of great help.
So, the basic ground plant on my example world is a red fern-like plant, I added larger fern like plants to the enviroment as well to fill it out, but they're basically background. There was also a lagoon in my example, which had a red seaweed-like plant as the basis for that ecosystem.
2.) Adding a Link...
It's easiest to just add links to the chain from the foundation up, one by one. So, the first species you might create will probably be some form of herbivore, the next a carnivore or omnivore, and then so forth until you reach the 'apex' predator of the ecosystem.
a.) Designing a Species.
In my office (unless my younger sister made off with it again) is a rather tattered book called the "Macmillan Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals: A Visual Who's Who of Prehistoric Life". It's almost as old as I am, but... while the information is out of date, it's a great place to look through if you're creating an alien lifeform... as it includes life forms that are rather strange and alien alongside the usual dinosaurs, reptiles, and sabre-toothed cat.
Despite what many people say when they talk about alien life, I don't necessarily believe alien life forms need to be extremely different from terrestrial life forms. Form follows function, and if the creature you're designing lives in an earth-like environment and has a ecological niche similar to a current or prehistoric earth animal's there's no reason for convergent evolution not to create a creature of roughly similar appearance and abilities. Of course, ecological niches are partly determined by what the prey item for the creature is (be it microbial life, plants, or another animal) this means it's best to start with the bottom and work your way up the food chain.
i.) Basic Classification.
The easiest way to design a creature, from the ground up is, in my view, to go through the basic 'classification' tree of the life form, this can be done by asking a series of simple questions.
Among animal life on our planet there are two basic types... Vertebrates or Invertebrates. Essentially, Vertebrates are life with an internal skeleton, or at a minimum a spinal cord. Invertebrates are life with an exoskeleton. As this is alien life we're discussing, there is a third possibility, a hybrid of sorts. A creature with an internal and exoskeleton. If you want 'giant insects' these hybrids are the only real viable way to go, as exoskeletons aren't the most efficient structure for larger creatures. Of course there are also possible invertebrates which lack exoskeletons like sponges, jellyfish, and anemone.
Next is the question of how it moves... Does it walk, swim, float, fly, crawl, slither, or is it anchored and stationary? Animal life either has to move, or is anchored in a current bringing food to it. Of course, most animal life we're interested in tend to be mobile.
Once you've determined if it moves, the next question is how many limbs the creature has. The most common large life-forms on earth tend to have four limbs, as there are particular advantages and disadvantages to having fewer or more limbs that make four limbs ideal. This is less true for stationary, water-bound life, and for the smallest of life forms such as insects.
Then comes the question of purpose of the limbs, are some used for grabbing, are they all legs, and so forth.
Finally we come to the question of the creature's means of obtaining food. Most life with which we are familiar has a mouth, but not all life does. One should also determine it's primary food source at this stage.
If one wants to go really into detail, you can even map out the evolutionary tree of your animal, but that strikes me as being rather excessive.
ii.) Important Details.
When you look up most descriptions of animals on say wikipedia, the first things they describe is the creature's size and weight. These are important details to know, as most creature's size is important in determining how dangerous they are. A number of other important details include such things as bite force, any natural weapons, scales, feathers, fur, or other external coverings, and the accuracy of a creature's senses.
Senses are surprisingly important, especially when designing an animals behavior. As an example, the Grizzly Bear is known to have very poor eyesight. As a result, the bear tends to shift it's weight from side to side when figuring out how distant a potential prey item is (using parallax instead of normal depth perception). Animals can have sensitivity to things besides the human five senses (sight, sound, taste, touch, and smell). As sharks can detect electromagnetic fields, a number of mammals can use echolocation, some birds can sense compass directions, and many animals ranging from snakes to spiders can detect tremors from footfalls or movement of a fluke in water.
Another important point to consider is whether a creature is endothermic or exothermic (warm or cold blooded). Warm blooded animals have to feed much more often then cold blooded animals and are considerably more active. This can have profound effects on the ecology as one of the determining factors to predator and prey ratios is how active the predator is.
Lastly is the pure appearance and coloration of a creature. Animals are not necessarily colored just for concealment, and even if you are coloring a creature for concealment, be sure to remember that what may be hard to see on earth may be very visible on another world.
iii.) An Example Species
The Alien Fisher is a highly active water based amphibian roughly 2 meters in length with a head around 50 centimeters in length and a total weight of around 50 kilos. It feeds on invertebrate and jaw-less fish which live in the local lagoon. It's vision is poor and it utilizes it's bodies unique electromagnetic senses to identify prey in the local environment.
Unusually, the Alien Fisher features a second set of jaws within it's bear-trap like mouth. To feed, it will snap its jaws around a large fish and hold it in place, thus allowing the second jaws to tear the fish apart at its leisure.
b.) Extrapolating from Your first species.
A quick look at that example which I just wrote immediately suggests the existence of other species. There's mention of jawless fish and other invertebrates. Which means there are other things in the ecosystem which can be mentioned and so forth. Very quickly you can develop an ecosystem as a result.
C.) Designing the Apex Predator.
The one part of the ecosystem that is almost invariable to feature in any story set on an alien world is going to be the planet's Apex predator, that thing at the top of the food chain. The worms of Dune, the Rancors of Dathomir, and Krayt Dragon of Tatooiene are all examples of apex predators from the Science Fiction genre.
Of course, on most worlds where an intelligent life-form has evolved, it's usually that life form which is the apex predator.
In most fantasy worlds, the apex predator is the Dragon, and honestly when designing a creature to act as the apex predator, creating something with a relatively equal threat level is probably quite appropriate. Another good example could be found in Jurassic Park, where the heroes are continually confronted with escaping the apex predator of the dinosaur age, a Tyrannosaur.
This doesn't necessarily mean that an apex predator need to be massive, consider for example modern apex predators. Wolves, lions, and tigers, while large are not necessarily terrifyingly so. I've often thought that a far more frightening enemy for a group stranded in the Dinosaur age would be a creature like Eotyrannus.
Well, if you're a five foot nothing human, do you think a Tyrannosaur will bother with you? It's roughly like a siberian tiger bothering with a mouse, it's not worth the effort. No, a creature that is small enough to consider a human an ideal prey item is better because suddenly we have a reason for the thing to chase you. In the case of this particular creature... well, it hunts in packs.
Never underestimate choosing a pack hunter. As a singular foe may work great as a central opposing figure for a story, a group ups the danger level and suddenly turns a duel to a death into an all out battle.
While a giant opponent may well be awe inspiring, it does not necessarily make the best opponent. Once again, think back to Jurassic Park and Lost World by Michael Crichton... which dinosaur is the one that is rendered as the most dangerous? The Velociraptor (that wasn't really a velociraptor).