Scientists disagree on how to classify biomes, so don’t be surprised if you hear of the 5 major biomes on earth, the 6 major biomes, the 7 major biomes, all the way up to 10 major biomes. In some classifications, for example, freshwater and saltwater biomes are lumped together into one aquatic biome; some divide forest biomes into temperate, tropical and boreal (taiga). And then there are some scientists’ super-specific classifications of biomes that number by the dozens, where there are, for example, 12 separate freshwater biomes.