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Phototaxis by the Dinoflagellate Gymnodinium splendens Lebour *
Author(s) -
FORWARD RICHARD B.
Publication year - 1974
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1974.tb03659.x
Subject(s) - phototaxis , circadian rhythm , dinoflagellate , biology , stimulus (psychology) , zoology , botany , neuroscience , psychology , psychotherapist
SYNOPSIS A microscope‐television system was used to monitor quantitatively the behavior of Gymnodinium splendens Lebour in response to light. The predominant behavioral sequence upon stimulation is (a) an initial 2–5 sec cessation of movement (stop‐response) followed by (b) positive phototaxis. The action spectra for each response are identical, having maxima at 450 and 280 nm. Upon measuring the percent response to a range of stimulus intensities, it is apparent that a stop‐response is not a behavioral prerequisite for phototaxis. An identical circadian rhythm in photoresponsiveness is observed for phototaxis and for the stop‐response with greatest light sensitivity occurring during the first 4 hr of the entrained light period. The implication of phototactic sensitivity and the phototactic circadian rhythm in diurnal vertical migration is discussed.