Refraction and spitting fish
Just as light from water into air refracts, so too does light refract when it travels from air into water. The archerfish spits water onto bugs sitting on overhanging branches. The bugs get knocked off their perch and fall into the water where they get eaten by the archerfish.
The archerfish must make allowance for refraction in its spit aim.
Using FAST SOFA, here the light travels from fast to slow so the light is bent towards the normal line as it passes through the surface (boundary).
The archerfish makes allowance for this refraction whatever angle it comes at, and does not miss with its spit.
