Phototaxis
![Phototaxis of Platynereis dumerilii nectochaete larvae: Some larvae show positive phototaxis by swimming towards the light. Other larvae show negative phototaxis by swimming away from the light. First, the light comes from left and then from the right side. When the light direction is switched the larvae turn. The side where the light is coming from is indicated by a white bar. Some negatively phototactic larvae are tracked. The larvae display mixed phototaxis, some negatively phototactic larvae are tracked. The scale bar represents 2 mm.[3]](/uploads/202502/02/-Neuronal-connectome-of-a-sensory-motor-circuit-for-visual-navigation-elife02730v006.ogv4521.jpg)
![Phototaxis of Platynereis dumerilii nectochaete larvae: The larvae turn when the light coming from the left is switched on. While the larvae turn they bend their body with their longitudinal muscles. The larvae show two dots on the head, which are the shading pigment of their adult cup eyes that mediate phototaxis. The direction where the light is coming from is indicated by white bars.[3]](/uploads/202502/02/-Neuronal-connectome-of-a-sensory-motor-circuit-for-visual-navigation-elife02730v007.ogv4521.jpg)
Phototaxis is a kind of taxis, or locomotory movement, that occurs when a whole organism moves towards or away from stimulus of light. This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive light for photosynthesis. Phototaxis is called positive if the movement is in the direction of increasing light intensity and negative if the direction is opposite.