If you can’t wait for the Terraria 1.4.5 update to land ... It introduces a fresh biome called the Plains Deep Caves to the sandbox game, taking you even further underground than the initial ...

The map shows the distribution of the global ecosystems or biomes.

The biotic parts of the ecosystem, which include bacteria, flora and fauna, have a complex relationship with the abiotic components - changing one will lead to a change in the other.