Blurry eyesight is the sharpest spider sense

摘要

For most of us, blurred vision is a bad thing, if only because It means we're drunk or have to buy a new pair of glasses. For one jumping spider, though, if s how it catches dinner. Adanson's house jumper {Hasarius adansoni) pounces on unsuspecting prey, but to hit the target it has to be an excellent judge of distance. It is - paradoxically, because part of its visual field is permanently out of focus. Ifs the only animal known to perceive range in this way. Mitsumasa Koyanagi of Osaka University in japan and colleagues knew that the Adanson's house jumper has four layers of light-sensitive cells in its retinas.