The Effect of Oxygen on the Concentration of Haem in Invertebrates

In Daphnia the haemoglobin content of the blood is known to increase in water that is deficient in dissolved oxygen and to decrease in well-aerated water. This is also true of other Cladocera, e.g. Chydorus. Conchostraca in poorly aerated water gain haemoglobin rapidly, but in well-aerated water they lose it slowly; Daphnia gains and loses it at the same rate. Larvae of the dipteran insects Chironomus and Anatopynia, and young of the pond snail Planorbis, synthesize more blood haemoglobin in poorly aerated than in well-aerated water. The annelid worms Arenicola, Scoloplos and Tubifex do not synthesize more blood haemoglobin in poorly aerated water. The haemoglobin content of tissue cells may increase when animals are in poorly aerated water and decrease in well-aerated water. This is so for muscles and nerve ganglia of Daphnia and Conchostraca, but not for muscles of the pond snail Physa or parenchyma of a rhabdocoele worm. Cytochrome in muscles of Daphnia and Conchostraca increases and decreases in amount, just as haemoglobin does, with decrease and increase of environmental oxygen.