When animals are deprived of oxygen they die.
Explanation;
Oxygen is an important gas in any animal's life. Animals need it to survive.
Oxygen is required mainly for the process of cellular respiration, a process which plants use to generate energy that is required by the cells to carry out basic functions such as growth and movement. Without these basic functions animals can not survive. Therefore; when animals are deprived of oxygen, they may utilize nutrients through anaerobic (without oxygen) respiration, after which they will eventually die.