快猫短视频

AN electric 鈥渟ixth sense鈥� unerringly guides paddlefish to their prey,
researchers in the US have discovered. They say that young paddlefish (
Polyodon spathula) rely exclusively on this electric sense to hunt their
food in the murky waters of the Mississippi river.

Paddlefish get their name from their long snout, or paddle, which is studded
with sensory organs that can detect electric fields. Adult fish have a simple
technique for catching their food. They feed by swimming around with their
mouths open, filtering plankton out of the water. But young paddlefish capture
their prey individually.

To discover how important the electric sense is, a team led by Lon Wilkens at
the University of Missouri-St Louis blocked off young paddlefishes鈥� other senses
to see whether they could still locate their favourite meal of water fleas. The
St Louis researchers prevented the fish from smelling the water fleas by
stuffing plugs of jelly up their 鈥渘ostrils鈥�, and they encased the fleas in
pellets of jelly so that the fish would not be alerted by the fleas鈥� movements.
They also added a plankton extract to the water to prevent the fish picking up a
chemical cue.

The researchers then put these fish in the dark and tested whether they could
distinguish pellets of jelly containing water fleas from those without. The
paddlefish homed in on the pellets with the fleas, but ignored those without.
The researchers also showed that the fish would attack an electrode that
simulated the electric field produced by a water flea, showing that the young
fish rely only on their electric sense when hunting.

鈥淚t鈥檚 a nice study, because it鈥檚 such a spectacular animal,鈥� says Carl
Hopkins, a neurobiologist at Cornell University. Other fish, such as sharks and
rays, also use an electric sense to hunt their prey. But zoologists have known
that paddlefish have electric sense organs for only 10 years, says Hopkins. This
is the first time that anyone has shown that young paddlefish exclusively use
their electric sense when they hunt.