Water fleas stand the heat and stay in the city

One of the most dramatic visuals of the 21st century is the sprawling skyline of a city. Glass-paned buildings as you look up, endless pavement as you look down. Cars honk. Tailpipes leak out pollutants. Lightbulbs buzz as a metropolis works into the night. What you do not necessarily see or hear... but might feel... is the heat. Because of human activities, there is an increase in air temperatures as you move into a city from its rural edges. This urban-rural temperature gradient is called the ‘urban heat island’ effect.