Each water strider leg has roughly 750,000 hydrophobic microhairs per square millimeter — they trap air and prevent the leg from breaking the water surface.
JournalGao & Jiang (2004), Nature2004Share →
Water Strider
Gerris remigis
Walks on water. Each leg has millions of waterproof hairs. The marine cousin lives on the open ocean.
Curated and rated by Sheriff Six-Legs and The Wild Pest field team · Six Legs Score™ (77/100, Outlaw tier) · Published Apr 25, 2026 · Updated Apr 28, 2026 · Released CC BY 4.0
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Six Legs Score™
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Water striders walk on water using surface tension — each leg is covered in millions of microscopic hydrophobic hairs that trap a layer of air, preventing the leg from breaking through the meniscus. They generate propulsion by rowing with the middle pair of legs at speeds up to 1.5 m/s — equivalent to a human swimming at 100+ km/h. The marine water strider Halobates is the only insect that lives on the open ocean.
Size
8-20 mm depending on species; G. remigis ~15 mm
Lifespan
1 year
Range
Worldwide on freshwater; Halobates on open tropical/subtropical oceans
Diet
Insect prey on water surface
Found in
Ponds, lakes, slow-moving streams; Halobates on open seas
Field guide
Family Gerridae — the water striders, also called pond skaters or Jesus bugs — contains about 1,700 species worldwide. The defining adaptation is the ability to walk on water by exploiting surface tension. Each leg is covered in approximately 750,000 hydrophobic microhairs per square millimeter that trap air and prevent the leg from breaking the meniscus, allowing the strider to stand and skate on still water. The hind and middle legs serve different functions: middle legs row, providing propulsion at speeds up to 1.5 m/s; hind legs steer. The forelegs are used to detect surface vibrations from struggling prey insects (mosquitoes, drowning flies, midge larvae) and to grasp them. Water striders feed by piercing prey with their stylet-like mouthparts and injecting digestive enzymes. The genus Halobates contains the world's only truly oceanic insects: five species live their entire lives on the open ocean surface, hundreds of kilometers from land, surviving on fish eggs, drowned insects, and zooplankton. Despite the open-ocean lifestyle, Halobates is wingless and never enters water — she would drown.
5 wild facts on file
Water striders can skate at 1.5 meters per second — equivalent to a human swimmer moving at over 100 km/h relative to body length.
JournalHu et al. (2003), Nature2003Share →
The marine genus Halobates is the only insect that lives on the open ocean — five species spend their whole lives on the sea surface.
JournalAndersen & Cheng (2004)Share →
Water striders detect prey by sensing vibrations on the water surface — each leg acts as a sensitive ripple-detection antenna.
EncyclopediaEncyclopedia of LifeShare →
There are about 1,700 species of water strider (Gerridae) — found on every continent except Antarctica.
AgencySmithsonian InstitutionShare →
Cultural file
Water striders are a flagship species in invertebrate biomechanics research. The 2003 Hu et al. paper in Nature explained the propulsion mechanism (vortex-shedding from the rowing legs); the 2004 Gao & Jiang paper documented the microhair architecture. Both have been cited thousands of times and inspired water-walking robots. Halobates is the only documented oceanic insect on Earth — a key data point in why insects largely failed to colonize the marine environment.
Sources
JournalGao & Jiang (2004). Nature2004JournalHu et al. (2003). Nature2003
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