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Light responses of Daphnia pulex
Author(s) -
Stearns Stephen C.
Publication year - 1975
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1975.20.4.0564
Subject(s) - daphnia pulex , morning , white light , light intensity , circadian rhythm , daphnia , blue light , biology , wavelength , pulex , red light , zoology , optics , botany , crustacean , physics , neuroscience
Individual Daphnia pulex were tested for activity responses in different wavelengths of light at the same intensity and at different times of day in white light at fixed intensity. The distance a daphnid moved in 5 min varied inversely with the wavelength of incident light. Daphnids tended to move vertically between 480 nm (blue) and 735 nm (red) and horizontally at 440 nm (violet) and in white light; this observation corroborates Smith and Baylor’s description of color dances. Daphnia pulex has a circadian activity rhythm. Total activity was low at night, increased to a peak in the morning, then declined through the afternoon. The color of ambient light is probably not a reliable indicator of the presence of phytoplankton in the water.