Taxis response is to move towards or away from the stimulus. If the organism moves towards the stimulus the taxis is positive, while if it moves away the taxis is negative. For example, flagellate protozoans of the genus "Euglena" move towards a light source. This reaction or behaviour is called "positive phototaxis", since phototaxis refers to a response to light and the organism is moving towards the stimulus. Many types of taxis have been identified, including: Depending on the type of sensory organs present, a taxis can be classified as a "klinotaxis", where an organism continuously samples the environment to determine
Yellow-Top taxis Yellow-Top taxis Yellow-Top taxis are a collective group of individually owned taxis in Singapore. The name is derived from their yellow top and black body. The "Singapore Taxi Transport Association" ("STTA") is a union catering to those private taxi drivers. The Association mainly takes care of administrative matters, such as the purchasing/selling of licenses and new vehicles. In 1933, Wearnes introduced the first private Yellow-Top taxis. These cabs were the first of their kind in colonial Singapore. The number of taxis in the group has declined significantly due to competition from Uber and Grab. In the late 1960s the first