Respiration may refer to: Respiration (physiology), the transport of oxygen to cells where cellular respiration takes place Cellular respiration, the process in which molecules are converted into usable energy Anaerobic respiration, cellular respiration without oxygen Aquatic respiration, the process of animals extracting oxygen from water Carbon respiration, a concept used in calculating carbon (as CO2) flux occurring in the atmosphere Ecosystem respiration, measure of gross carbon dioxid… (More on Respiration)