The influence of size, temperature and oxygen tension upon the respiratory metabolism of the terrestrial amphipod Talitrus (Talitroides) pacificus Hurley, 1955

1. 1. The oxygen consumption of Talitrus pacificus, measured at 20°C and in normoxic conditions, varied with body weight according to the equation O 2 = 1.245 W 0.462 for N = 45(1.4–34.1 mg) and r = 0.725 ( P < 0.05). 2. 2. The weight (mg) specific oxygen consumption (“respiratory rate”) of T. pacificus ranged from 1.171 (1.4 mg animal) to 0.148 (34.1 mg animal) in μ 10 2mg/hr. 3. 3. The respiratory rates of T. pacificus acclimated to 20°C increased with rising temperatures, particularly in the range 10–15°C ( Q 10 = 3.65); a Q 10 = 1.09 indicated a zone of respiratory homeostasis between 25 and 30°C. 4. 4. In declining oxygen tensions, T. pacificus regulated the rate of oxygen consumption down to 105 or even 70 mm Hg of O 2. 5. 5. No animals out of groups of 10 survived after 40–45 min in an anoxic condition (100% nitrogen).