Metabolic Rates of Ephemerid Nymphs From Swiftly Flowing and From Still Waters

1. The oxygen consumptions of the small ephemerid nymphs Ephemerella ignita and Coenis sp. are (anaesthetised at 10° C.) 950 and 290 c.mm./gm./hour. Their habitats are respectively a stream and a pond. 2. The oxygen consumptions of the large ephemerid nymphs Ecdyonurus venosus, Ephemera danica and E. vulgata are (anaesthetised at 10° C.) 604, 370 and 278 c.mm./gm./hour. They live, respectively, under stones in a swift stream, burrowing in sand in a stream, and burrowing in mud in a pond. 3. Ecdyonurus venosus is less resistant to oxygen deficiency than Ephemera danica and E. vulgata; and Baetis rhodani (swift stream) is less resistant than Chloeon dipterum (pond).