From Science Codex: Archer fish hunt insects with water jet 6 times stronger than their muscular power
Archer fish knock their insect prey out of overhanging vegetation
with a jet of water several times more powerful than the fish's muscles.
New research now shows that the fish generate this power externally
using water dynamics rather than with any specialized internal organs.
The research, published Oct. 24 in the open access journal PLOS ONE
by Alberto Vailati and colleagues from the University of Milan,
provides the first explanation for how archer fish can generate such
powerful jets to capture their prey.
Other animals like chameleons and salamanders store energy in
collagen fibers in their bodies and abruptly release this stored energy
to project their tongues at high speeds, but previous studies on archer
fish have ruled out such specialized organs as the source of the
powerful water jets.
The authors of the current study used high-speed video recordings of
archer fish knocking insects out of overhanging plants to study the
mechanics of the water jet and found that the fish could modulate the
velocity of the jet to create a single large water drop that hit the
prey with a large force. According to the authors, this approach avoids
the evolutionary costs needed to develop special internal structures to
store these large amounts of energy.
"The origin of the effectiveness of the jet squirted by archer fish
has been searched for inside of the fish for nearly 250 years. The
striking finding of our work is that a large amplification of muscular
power occurs outside of the fish and leads to a very powerful impact of
the jet with the prey" says Vailati.