How does life change in aquatic biomes as depth increases?

LIfe much change in that there is less light and higher pressure. Therefore the organisms must be able to survive with little vitamin D (since that comes from the sun) and also they must not need as much warmth or as much oxygen. Most have their own way to produce light (jelly fish) and they must have a flexible skeleton so that it does not get "smooshed"(crush) by the high pressure.