The functional significance of the haemoglobin in a marine nematode, Enoplus brevis (Bastian).

An animal chamber and a simple microspectrophotometer for investigating the in vivo oxygenation of the haemoglobin of E. brevis are described. The in vivo absorption peaks of this haemoglobin occur at similar wavelengths to those of other nematodes. Mean values, given with their corresponding standard errors, occur at 577.6 plus or minus 0.6 nm, 543.6 plus or minus 0.5 nm and 421.7 plus or minus 1.9 nm for oxyhaemoglobin, and 555.2 plus or minus 0.9 nm and 432.2 plus or minus 1.3 nm for the deoxygenated pigment. The percentage of oxyhaemoglobin in the pharynx of E. brevis decreased at external oxygen tensions of less than 20 Torr, and the pigment was completely deoxygenated at 5 Torr. Stimulation of individuals in aerated sea water for 1-2 min caused a partial deoxygenation of the haemoglobin; the pigment reloaded soon after this period of increased activity had ended. The functional significance of the haemoglobin of E. brevis is disucssed.