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The Monterey Bay Whale Watch video, shot in May, shows up to 1,500 dolphins leaping in and out of the water, racing along just in front of the two whales.
The behaviour, which is termed by experts as 'snout-riding', involves swimming and splashing just in front of a whale's head in order to encourage it to lunge forwards. This movement then creates waves that the dolphins are able to ride for fun.
It's the same type of behaviour that can be observed when dolphins swim near the bow of a moving ocean vessel, leaping in and out of the waves and appearing to play with it.
"The dolphins seem to really enjoy this, and the whales aren't really bothered," Nancy Black, marine biologist at Monterey Bay Whale Watch, told the San Francisco Chronicle.
Black estimates there were not far off 1,500 dolphins, of two different species in total.
Some were Pacific white-sided dolphins, which are regular visitors to the California coast.
If you look carefully, you can spot the difference between these dolphins and the rarer northern right whale dolphins, which don't have dorsal fins and are a dark black colour on top, with a white underside.
Meanwhile, researchers in France have attempted to measure 'dolphin happiness' for the first time.
The study, published in the journal Applied Animal Behaviour Science, is part of a three-year project designed to measure the welfare of dolphins.
"We wanted to find out what activities in captivity they like most," lead researcher Dr Isabella Clegg told the BBC. "We found a really interesting result - all dolphins look forward most to interacting with a familiar human."
The researchers noted that when a dolphin spotted a trainer it was familiar with, it would spend more time around the edge of the pool and peer above the surface of the water.
"We've seen this same thing in other zoo animals and in farm animals," Dr Clegg added. "Better human-animal bonds equal better welfare."
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