Oxygen Consumption and Ammonia Excretion of Marphysa sanguinea (Polychaeta: Eunicidae) in Relation to Body Mass and Temperature

(1) Background: Marphysa sanguinea is a polychaete with high economic value and ecological importance. Information on metabolism is important to understand the physiological action of organisms. (2) Methods: The rates of oxygen consumption (R) and ammonia excretion (U) were measured using different temperatures (T) and body mass (M) levels. The activation energy (E) was calculated using the universal temperature dependence theory. (3) Results: Oxygen consumption presented a curve with an upward trend first, and then a downward trend, and ammonia excretion displayed a “U” curve. The effects of temperature and body size on oxygen consumption and ammonia excretion rates were extremely significant. Small individuals had higher metabolic rates than large polychaetes at the same temperature. The relationship between oxygen consumption, ammonia excretion, and M was expressed as Y = a·Mb, bR = 0.56 ± 0.09, and bU = 0.35 ± 0.30. The oxygen consumption activation energy was ER = 0.68 eV, and the ammonia excretion activation energy was EU = 0.53 eV. The O:N ratio at different temperatures and body sizes was in the range of 3.55–56.44. (4) Conclusions: The results not only provide basic data on the metabolism of M. sanguinea but also insights to understand the relationship between animal metabolism and ecological factors from different perspectives.