Creatures 1 had no real ecology in it - although there were a few herbs, they did not tend to interact with one another. The first glimpse of an ecology came with the advent of Life Kit #1 and the Beelacanth, the bees update, and the Cloud Layer Butterflies. Some third-party objects interacted with their environment.
Creatures 2 was the first of the series to include a real ecological system, including weather. The main categories of lifeforms interacting are plants (including flowers and fruits), insects, critters and fish. All of these were thought to interact not only with norns, but also between each other. For example:
- Bats can eat fruits and fungi
- Borland the C-monster eats Zander fish when they grow too plentiful
- Bees pollinate flowers so that they produce fruits, then seeds, which later grow into more plants
Life other than creatures-with-brains is classified into 'permanent' or 'ecological' categories - permanent means that it cannot die out, and ecological means that it can. Having fun with ecology (taking care of plants, helping ants getting food so that they don't disappear...) is good way to enjoy Creatures 2; there are hundreds of COBs on the web that can improve this particular aspect of the game. The Ecology Kit was included with Creatures 2 to help players. However, if you are feeling more destructive, there exists a Global Warming Cob...
Creatures 3 further expanded the ecological themes of Creatures 2. There are many more species and lifeforms, more types of interaction between them, and to make it a little bit more challenging, this time the player really has the opportunity to modify it with tools to maintain all of the species on the Ark. The thing is that one has to be very careful: bioenergy is rationed, and you can't produce as many seeds as you want. This is the main reason why you have to be very careful of what you do before all your ecological "credit" is gone.
The Marine Terrarium is certainly the most interesting of these. In this room there is a little sand beach for your norns, but the main idea of this room is to provide you a huge aquarium with many types of fish, plankton and seaweed, all of them interacting of course. Gaia is a cool addition if you encounter difficulty maintaining the ecology in Creatures 3.
See here for official ecology outlines.
- See also: the official ecology category.
There are also things to do with the ecology in Docking Station. No more bioenergy, and the few species that appeared in the Shee Ark seem to be able to survive by themselves. As there is much less room than in Creatures 3, the possibilities for complex ecological systems are quite limited. However, you can still add things to play with, and the different norn packs often include new species of plants or critters. Metarooms might also come with their own ecology.