Water Strider
Aquarius elongatus
A hunter that glides on the water’s surface tension
The water strider has a slender body; water-repellent microhairs on its midlegs and hindlegs let it stand and glide on surface tension, not merely because it is light. It senses ripples to find insects fallen on the water, gripping prey with its forelegs while the other legs paddle — an active ambush predator.
Key figures
- Length
- About 14–17 mm; slender, streamlined body
- Life cycle
- Several generations a year in warm regions; adults live for months
- Habitat
- Ponds, streams and slow-flowing water
- Diet
- Carnivorous; preys on insects that fall onto the water, locating them by surface ripples
- Walking on water
- Dense water-repellent microhairs on the midlegs and hindlegs work with surface tension to keep it afloat
- Paddling
- Short, strong forelegs grip prey while the midlegs and hindlegs paddle and steer
Life cycle
Egg → Nymph (multiple molts) → Adult
Ecological role
The water strider is an active predator in the surface food web, feeding on insects that fall onto the water or fail to emerge properly, and it is also a sensitive indicator species for water pollution.
Did you know
The water strider stays afloat not because it is light, but because dense water-repellent microhairs on its legs magnify surface tension enough to bear its weight; shave off the hairs and it sinks at once.
Range
Most freshwater habitats across China; widespread in East Asia
Status
Common
Anatomy
- Midleg — The longest leg; sculls like an oar and provides most of the propulsion
- Foreleg — Short and powerful, used to seize prey that falls onto the water
- Hindleg — Handles steering and braking, working with the midlegs to control gliding direction
- Body Surface — Coated in waxy, water-repellent hairs, so it stays dry even when briefly pressed into the water
- Compound Eye — Bulges to the sides, helping it detect the faint ripples made by prey on the water
- Antenna — Short and slender, serving both touch and the sensing of vibrations on the water
Open the interactive 3D specimen