Abstract

O'Mahoney, P.J. and R.J. Full. 1984. Respiration of crabs in air versus water. Comp. Biochem. Physiol. 79A: 275-282.

l. Oxygen consumption, V(O2), ventilation volume (V) and O2 extraction (Ext) were measured for three species of crabs: the terrestrial Gecarcinus lateralis, the amphibious Cardisoma guanhumi, and the aquatic Callinectes sapidus. In air the V(O2) of the crabs was ranked Gecarcinus > Cardisoma > Callinectes. In water the V(O2) was Callinectes > Cardisoma > Gecarcinus. 2. When terrestrial Gecarcinus was submerged in water, V(O2) fell to 1/7 of its aerial value because both V Ext fell. When aquatic Callinectes was exposed to air, V(O2) fell to 1/3 of its aquatic value because both V and Ext fell. Only the amphibious Cardisorna maintained V(O2) constant in both media; in water V was increased to offset a fall in Ext. 3. All species behaved as vo: conformers .when they were exposed to short-term hypoxia; the effect was more prot~ounced in the aquatic environment. 4. Severe short-term hypercapnia caused no change in the aquatic environment; but it stimulated increased V and decreased Ext in air. 5. Such effects are consistent with vertebrate responses: O2 seems to be the most important regulatory factor of respiration in water and C02 is the most important in air.