How do the living conditions of organisms in the ocean differ from their living conditions on land?

If we talk about the living conditions in water and on land, then there are really many differences and they are quite significant. So, one of the main differences can be considered the way of oxygen consumption. There are also some peculiarities in adapting to gravitational influences. Also, photosynthesis in plant organisms has its own characteristics in water and on land. There is also a big difference in the way you move in space. Another important difference is in the breeding method. As you can see, there are a lot of differences and they are very significant.