Oxygen uptake and nitrogen excretion in two cephalopods, octopus and squid

1. 1. During exercise of the squid Illex illecebrosus swimming up to 3 body lengths/sec, resting values at 15°C for both oxygen uptake (11.3 mM O₂/kg per hr) and ammonium excretion (1.4 mM NH₄/kg per hr) increased about five-fold; both parameters were always correlated with an excretory O:N ratio of 15. 2. 2. In Octopus, both oxygen uptake and ammonium excretion rates at rest were about five-fold lower than in Illex. 3. 3. Urea was 30% of the measured nitrogen excretion in Octopus and 24% in Illex at rest, respectively. 4. 4. During swimming, urea excretion in Illex was irregular and not correlated with ammonium excretion. 5. 5. Glutamic dehydrogenase activity with a significant capability for glutamate oxidation (0.3-3.1 Units/g tissue; 25°C) as well as adenosine deaminase activity (0.4-3.3 units/g tissue) were found in several Illex tissues.