Dolphins can maintain round-the-clock auditory and visual vigilance

Washington, May 2 (ANI): In a new research, scientists have found that dolphins are able to remain continually vigilant for sounds and visuals for days on end.

The research was done by scientist Sam Ridgway from the US Navy Marine Mammal Program and his colleagues from San Diego and Tel Aviv.

The team set about testing two dolphins' acoustic and visual vigilance over a 5 day period to find out how well they functioned after days without a break.

First, Ridgway and his colleagues, Mandy Keogh, Mark Todd and Tricia Kamolnick, trained two dolphins to respond to a 1.5 s beep sounded randomly against a background of 0.5 s beeps every 30 seconds.

According to Ridgway, the sounds were low enough for the dolphins to barely notice them as they swam through their enclosure, but the animals sprung into action every time they heard the 1.5 seconds tone, even after listening to the sounds for 5 days without a break.

Their auditory vigilance remained as sharp as it had been 5 days earlier.

Next, Allen Goldblatt and Don Carder designed a visual stimulus to test the dolphins' vigilance while they continued listening to the repetitive beeps.

Knowing that the dolphins' binocular vision is limited because their eyes are situated on opposite sides of their heads, Kamolnick trained one of the dolphins, called SAY, to recognize two shapes with her right eye before training her to recognize the same shapes with the left eye, reasoning that if half of her brain was asleep during testing, the dolphin would only see the shapes through the eye connected to the conscious half of the brain.

But, the team were in for a surprise when they began training SAY's left eye. She already recognized the shapes, even though her left eye had not seen them previously.

Ridgway explained that the information must be transferred between the two brain hemispheres and suspects that the dolphin's inter-hemispheric commissures, which connects the two halves, may transfer the visual information.

Having trained both dolphins to recognise the shapes, the hard part began: monitoring and rewarding the dolphins continually over a 5 day period while the team tested the animals' responses to both the sound and visual stimuli.

Amazingly, even after 5 days of listening out for 1.5 s beeps amongst the 0.5 s beep background, the dolphins were still responding as accurately as they had done at the beginning of the experiment. (ANI)