Water striders walk on water using surface tension, hunting prey on pond and stream surfaces. Their welfare is affected by water pollution, surfactants, and habitat degradation.
Water striders occupy a highly specific ecological niche — the water surface — that is particularly vulnerable to pollution. Surfactants from household and agricultural chemicals break the surface tension that water striders rely on, trapping them in water where they cannot breathe or move effectively. This causes drowning stress and death. Pollution also depletes their insect prey. Their sensitivity makes them useful bioindicators of freshwater and marine surface health.