A Study of the Oxygen Consumption of Five Species of Leech

Abstract

1. The oxygen consumption of five species of leech has been investigated and considered in relation to their ecology. 2. Glossiphonia complanata and Erpobdella octoculata which are most common in, but not confined to, hard and soft water streams respectively, have their oxygen consumption dependent on the concentration of dissolved oxygen, at least in spring and summer. Their oxygen uptake is not affected by acclimatization overnight to a low level of oxygen, but the uptake of Glossiphonia at the higher oxygen concentrations is depressed in winter. 3. Erpobdella testacea has an oxygen consumption which is independent of the oxygen concentration between 6.0 and 3.0 ml./l., provided that the leeches have been acclimatized overnight to the oxygen concentration at which their uptake is measured. Ventilation of the body surface by dorso-ventral undulations appears to be an important factor in the maintenance of a high rate of oxygen uptake at low concentrations. This species is found in reed swamps. 4. Helobdella stagnalis, which is most abundant in stagnant eutrophic lakes, maintains a level of oxygen consumption which is independent of the oxygen concentration between 2.0 and 4.0 ml./l., even without previous acclimatization. 5. Piscicola geometra, which is virtually absent from stagnant water, has a higher rate of oxygen uptake than any of the other species under conditions of air-saturation, and its rate is strictly dependent on the concentration of oxygen in the water.