ARCHER FISH Living Water-Gun

newscientist.com

The Archerfish deploys one very unusual hunting technique that works every single time, making it one of the deadliest hunter nature has to offer. The Archer Fish or spinner fish belongs to a family known as the Toxotidae. It has an unusual habit of making tasty snacks out of small animals (really small) and insects that live on land.
They inhabit brackish waters of mangroves and estuaries and are mostly found in Australia, India, Polynesia and Philippines.

As mentioned, they target land-based preys but the question is, how do they make it possible? They use water as their weapon. They shoot a jet of water from their mouth, with the finesse of a marksman, to hit insects and other prey above the water surface.
They even adjust for the gravitational pull that acts on the jet of water and manage to hit their prey with high precision.

They have highly developed eyesight that allow them to adjust for refraction of light that takes place at air and water boundary. The optical illusion caused by refraction will usually shift the position of the targeted prey. While hunting, archer fish simply rotates its eyes so that the prey’s image fall in retina’s ventral temporal periphery. This allows them to pinpoint the exact location of the prey despite the optical shift at air-water boundary.

In order to shoot the water efficiently, archer fish will allow its lips to just break the water surface barrier.The force with which the archer fish will shoot the stream of water will also depend on the size of the prey and the force with which they hold on to the tree branches and shoots. The prey is never big and is almost always limited to small bugs and small lizards.
The use this same technique under water to hunt for snacks hiding under the sand, leaves and other debris.
References:
video.nationalgeographic.com
factslegend.com
newscientist.com
Wikipedia.com