<Tr> <Td_colspan="2"> <Ul> <Li> Rhadadotarsinae </Li> <Li> Trepobatinae </Li> <Li> Halobatinae </Li> <Li> Ptilomerinae </Li> <Li> Cylindrostethinae </Li> <Li> Charmatometrinae </Li> <Li> Eotrechinae </Li> <Li> Gerrinae </Li> </Ul> </Td> </Tr> <Ul> <Li> Rhadadotarsinae </Li> <Li> Trepobatinae </Li> <Li> Halobatinae </Li> <Li> Ptilomerinae </Li> <Li> Cylindrostethinae </Li> <Li> Charmatometrinae </Li> <Li> Eotrechinae </Li> <Li> Gerrinae </Li> </Ul> <P> The Gerridae are a family of insects in the order Hemiptera, commonly known as water striders, water bugs, pond skaters, water skippers, or jesus bugs . Consistent with the classification of the Gerridae as true bugs (i.e., suborder Heteroptera), gerrids have mouthparts evolved for piercing and sucking, and distinguish themselves by having the unique ability to walk on water . Gerridae, or water striders, are anatomically built to transfer their weight to be able to run on top of the water's surface . As a result, one could likely find water striders present in any pond, river, or lake . Scientists have identified over 1,700 species of gerrids, 10% of them being marine . </P> <P> While 90% of the Gerridae are freshwater bugs, the oceanic Halobates makes the family quite exceptional among insects . The genus Halobates was first heavily studied between 1822 and 1883 when Buchanan - White collected several different species during the Challenger Expedition . Around this time, Eschscholtz discovered three species of the Gerridae, bringing attention to the species, though little of their biology was known . Since then, the Gerridae have been continuously studied due to their ability to walk on water and unique social characteristics . Small gerrids have frequently been confused with the other semiaquatic bugs, the Veliidae . The most consistent characteristic used to separate these two families are internal genitalia differences . Since internal genitalia require specific training and tools to identify, it is almost impossible to tell a member of the Gerridae apart from a member of the Veliidae by external visual cues . One must study their habitat and behaviors to properly differentiate the two without looking at their specific anatomy . </P>

A water strider can walk on water because