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Negative Phototaxis in Blepharisma japonicum
Author(s) -
MATSUOKA TATSUOMI
Publication year - 1983
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.1550-7408.1983.tb02940.x
Subject(s) - phototaxis , biology , light intensity , elongation , biophysics , optics , botany , physics , materials science , metallurgy , ultimate tensile strength
The protozoan Blepharisma japonicum showed negative phototaxis caused by transient reversal of the direction of ciliary beat and changes of swimming velocity induced with varying intensities of light. The ciliary reversal occurred at 1–2 sec after a sudden increase in light intensity. When light intensity was decreased, no response was observed. Moreover, the ciliates swam fast in light areas but slowly in dark areas; the mean velocity of swimming was 80 μ m/sec at 5 × 10 2 lux but reached about 400 μMm/sec at 5 × 10 3 lux. In addition, the cell body elongated in response to light application; the mean length of the body was 308 μm at 5 × 10 2 lux, which increased to 397 μ m at 10 4 lux. Such body elongation seems to contribute to rapid swimming. Negative phototaxis may be an important behavior in B. japonicum because the organisms are killed by exposure to strong light.