The captain of a California whale-watching tour boat recently posted a video documenting a rare sight: twin whale calves swimming with their mother.

“This year is our 20th year owning a whale-watching business, and I have never heard of anyone even seeing a gray whale with two calves, never mind filming it,” said Dave Anderson of Captain Dave’s Dolphin & Whale Watching Safari in Dana Point. “I wanted to be absolutely certain that these were both calves that I was seeing by comparing the size of these three whales from above, so I put our drone up, and what I saw through the goggles made me want to give them all a big hug.”

Anderson stressed that it’s not known whether the whales are twins or whether the mother adopted one of them.

“There have been cases of dolphins adopting other dolphin calves of the same or different species into their pod,” he said. “We have seen this with a lone common dolphin that we saw for several years living in a pod of Pacific white-sided dolphins.”