117
Anatomy
Cells rotate
while swimming
Is the
photoreceptor
shaded by eyespot?
Photoreceptor
in state A
Photoreceptor
in state B
Photoreceptor
in state A
A signal
arises
Change of
swimming path
End of
shading
Time
Time
N
White
Light
White
Light
Light
UV and
Green
Y
FIGURE 2.80 Euglena gracilis phototaxis flow chart.