Archerfish Shoot Insects Out of Branches
The archerfish eats insects. How does the fish catch insects when they are in the water and the insects are above the water? The archerfish can shoot down insects that are on a low branch overhanging the water. The branch can be as far away as 3 meters high.
Actually the archerfish can shoot streams of water anywhere from 2 meter to 5 meters long. But they prefer to get the insects that are 1 to 2 meters away. That is because at this closer range, the adult archerfish can usually hit the insect on its first try. Their accuracy is that good.
This is amazing since water has a different light refraction property than air, so their aim must take this into account. Admittedly the young newborn archerfish can not aim this well. This is a skill that must be learned. So for the young, they must hunt in groups so as to not starve. In group shootings, there is greater probability of hitting an insect just by chance when many youngster are shooting at once.
They soon learn that the best angle of attack for the stream of water is at 74 degrees from the horizontal. Although adults can still aim accurately anywhere from an angle of 45 degrees to 110 degrees.
If an insect is close enough, an archerfish may be too lazy to aim and just leap up and catch the insect in its mouth.
Afterall, it does take some effort to shoot such powerful streams of water that can knock down prey such as grasshopper, spiders, and even butterflies.
According to Wikipedia, this is how they shoot ...
"it rotates its eye so that the image of the prey falls on a particular portion of the eye in the ventral temporal periphery of the retina and its lips just break the surface, squirting a jet of water at its victim. It does this using the narrow groove in the roof of its mouth. It presses its tongue against this groove to form a narrow channel, then contracts its gill covers to force a powerful jet of water through the channel."
Now, that's interesting.
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