What is the diversity of the animal world manifested in?

The first is the variety of conditions of existence. Three environments of existence (earth, water, air) have led to the emergence of water, air and of course ground and underground living beings. The second is the difference in the timing of the appearance of species: the first organisms appeared in water, then their descendants began to inhabit the land, then mastered the air environment. That is why the greatest variety of living organisms – in water and on land, they appeared much earlier, and they had time for speciation more. Since the conditions of existence on land are the most different – each species has occupied the so-called “ecological niche”, that is, it has adapted to certain living conditions: steppe, forest, desert, tundra animals.