By Rebecca Lewis @RebeccaSLewis
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The graceful creatures were spotted off the coast of South Africa as the large pod hunted for food.
Rainier Schimpf, a photographer from South Africa, took pictures as he followed the pod’s journey across the ocean.
As the dolphins churned the water and surfaced to breathe, one enthusiastic member of their group leapt into the air.
Putting on a spectacular show for its human spectators, the stunning creature jumped several feet into the sky.
The pictures, taken on June 22, show what Rainier believes to be dolphins sleeping with both eyes closed – an unknown occurrence.
The stunning mammals do not sleep in the same way humans do, instead one hemisphere of the brain will shut down and one eye will close while the other part remains active.
This allows the dolphins to surface above the water to breathe and to remain with their pod.
But these pictures show dolphins with both eyes closed and apparently fast asleep.
Rainier said: "We were able to follow the dolphins in the last few months.
“We followed certain groups over 120km along the South Africa coastline on one day.
“When the dolphins did not hunt, many of them had their eyes closed – on both sides.
“This was completely new to us and could contradict our understanding of dolphins’ behaviour."