Klinotaxis occurs in organisms with receptor cells but no paired receptor organs. The cells for reception are located all over the body, particularly towards the anterior side. The organisms detect the stimuli by turning their head sideways and compare the intensity. When the intensity of stimuli is balanced equally from all sides then the organisms move in a straight line. The movement of blowfly and butterfly larvae clearly demonstrates klinotaxis.
Tropotaxis is displayed by organisms with paired receptor cells. When the stimuli coming from a source are balanced equally the organisms show movement. Because of this, animals are able to move sideways, unlike klinotaxis where the organisms can move only in a straight line. The movement of Grayling butterflies and fish lice clearly demonstrates tropotaxis.
I don't understand the part , because of this the animals are able to move sideways. Could you explain?