维基百科 Tetragnatha is a genus of spiders containing hundreds of species. They are found all over the world, although most occur in the tropics and subtropics. They are commonly called stretch spiders, referring to their elongated body form. When disturbed they will stretch their front legs forward and the others in the other direction, thus being able to hide on blades of grass or similar elongated substrates. They are able to run over water. One of the biggest and most common species is T. extensa, which has a holarctic distribution. It can be found near lakes, river banks or swamps.[1] In the stratum of reed, tall grass or minor trees and shrubs those habitats are sometimes literally ruled by thousands of individuals of the stretch spiders who build their radial nets with sticky silk. A shift to cursorial behavior in the Hawaiian Tetragnatha species seems to have occurred very early on arrival of the ancestor on the island chain.[2]