Blind fish navigates by sucking water to create a 'force field' of water that reveals nearby objects

18:57 • 07.04.14

For humans in dark places, using touch and feel can help us ‘see’ where we’re going, the Daily Mail reports.

But for the Mexican blind cavefish, using touch alone isn’t enough.

Instead, in the absence of eyes, they’ve evolved an ability to alter the water around them, creating a force field of sorts that alerts them to the presence of obstacles.

The research was performed by a team at Tel Aviv University, Israel led by Dr. Roi Holzman.

When observing the blind cavefish (Astyanax mexicanus) in a tank, they noticed it was continuously opening and closing its mouth every few seconds.

The water comes in and is then discharged through their gills.

The sucking action, however, had not been noticed before, so Holzman and his team set about understanding why it did this.

They found that when they rearranged the objects in the tank, the fish moved much more slowly and sucked more often as it attempted to regain its bearings.

At 2.8 inches (seven centimetres) from a large object, the fish sucked twice as fast.

When 0.8 inches (two centimetres) away, it sucked six times as fast.

‘We hypothesized that repeated mouth suction generate a hydrodynamic velocity field,’ the researchers write in their paper.

Once water is sucked in it is then pushed back out through the gills, forming a noticeable pressure wave around the fish.

The researchers suggest that creating this wave makes the movements of the fish 60 times more accurate than without it.

This allows it to be incredibly nimble and agile despite not having eyes.

But no one is quite sure why the fish has developed this ability.

Some theories suggest it is a 'regressive trait' that has occurred over time.

But others think it may simply be part of the evolution process, with the fish losing its eyes as it had no need for them.

Whatever the reason, the use of water currents as a tool to 'see' makes this one of the most unique fish in the world.
 

Blind fish navigates by sucking water to create a 'force field' of water that reveals nearby objects