Oxygen consumption of Artemia salina was measured during development in 0.5 M NaCl at 25° C. A pattern is seen in which the rate of oxygen consumption increases rapidly within the first few hours after hydration, remains constant for a time, and then increases rapidly again while most of the embryos are emerging. This pattern is dependent upon surface area of the developing embryo. During emergence, the surface area of the embryo increases 172% over the surface area of the encysted embryo. During the same development period, oxygen uptake increases by almost the same factor.