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.
Crossing over is the swapping of genetic material that occurs in the germ line. During the formation of egg and sperm cells, also known as meiosis, paired chromosomes from each parent align so that similar DNA sequences from the paired chromosomes cross over one another. Crossing over results in a shuffling of genetic material and is an important cause of the genetic variation seen among offspring.
The phase of mitosis during which the chromosomes move toward separate poles of the cell is called anaphase
Oil is more dense than the water