Creating Something Different
One reason to create plants and animals is that they can give our world a different look and feel. The more we create, the more pronounced this impression, especially when we link choices and behaviors of our characters to the life around them. This could be steeds that are ferocious and require great strength of will to control, but could be predators which cause travel plans to change. James Cameron did this to great effect in the movie Avatar (italics).
Characters can learn hunting, attack, and defense skills based on those predators. Maybe they know what it means when a predator flees, such as when great white sharks suddenly swim away from a person in the water; it means an even bigger great white is moving in. This sort of thing is how we integrate everything. If done well, this can make our world stand out in a good way that makes audiences eager for more. The more life forms we create, the more different our world begins to feel.
How Often the Setting Will Be Used
If we’ll only write one book in this setting, the extra work to create many plants and animals may not be worth it. Just do what you need for the project. Some of what we create for one world can be used in another instead, so inventing things we don’t use right now is not an issue. In SF, we may have multiple worlds in a single work or across our career, so we can still just invent life forms for their own sake and figure out where to use them later. Integrating things is great, but that arguably matters more with humanoid species than plants and animals.
Time
It takes time we may not have to create unique plants and animals, though this time investment is less than with other things in this book. We can get around this by inventing during writing, but we must watch out for creating something without much depth or impact on our work. If inventing on the fly, always make a note to add this lifeform to your files and work it out in more detail, then touch up your depiction if necessary. Integrating it with other things is a continuous process anyway.
Do Our Creations Matter?
In the film and TV industries, having interesting plants and animals in the background is easy and fairly standard with today’s special effects, and they need no more than an appearance. It’s only when they affect character decisions or storylines that they achieve relevance, which is the point at which they should be mentioned in written stories. If we mention an irrelevant plant or animal in passing without some hint that it’s a large cat, for example, it can be off-putting, especially if we name too many in a row.
As a case in point, in my story “The Epic of Ronyn,” a character gets pelted with vegetables. I had originally named the different items he’s struck with, but beta-readers commented that they had no idea what I was talking about and it took them out of the scene. I wasn’t going to explain each item in the paragraph (and there was no room or reason to beforehand) because it wasn’t worth it, so I replaced my list of vegetables with the word “vegetables.” While not exactly descriptive, it helped the scene stay on focus.
On the other hand, “The Garden of Taria” story features a character who keeps invading someone’s home and preparing a meal for himself and sometimes her, too. All of their conversations occur while food is being prepared, consumed, or cleaned up. This provided a good chance to name and very briefly describe various items, but it proved challenging to keep it to a minimum. A few choice words are recommend when writing.
For example, consider this line: “She saw a line of yellow drops (italics) leading from kitchen to couch, discarded juna peels tossed here and there along the way, the perpetrator licking the running juices from dirty fingers as he popped another fruit piece into his mouth.” I added the italics to indicate the key words carefully strewn through this sentence to get across what the food is. Is this better than writing, “He ate a yellow citrus fruit called juna?” Both have their merits.