Nightly News | February 18, 2013
>>> finally tonight, the extraordinary sight in southern california , and what it might mean. put it this way. if you've ever spotted a dolphin out on the water in the wild, you know it's really something. but it's something else entirely when dolphins are just about all you can see by the thousands. perhaps even tens of thousands of them on the surface of the water at one time. some people have witnessed just that. we get our report tonight from los angeles , and nbc's diana alve alvear.
>> reporter: at first, there were just a few. then dozens, perhaps thousands of dolphins swimming near san diego . victor and maria morassi captured it on camera.
>> it was amazing, dolphins everywhere.
>> reporter: in just last month, another mega pod was spotted neara dana point up the coast. they usually travel in smaller groups. so what causes the mega pod? biologists believe it may have to do with the food chain , an all-you-can-eat buffet, tailor-made for dolphins.
>> we can suspect the food stocks are coming together and the individual pods are following those food stocks.
>> reporter: but explaining how thousands of dolphins congregate to feet at the same place at the same time is still a mystery.
>> dolphins are social creatures. whether they're calling their friends to come near, we don't know the answer to that. once they gather, though, we do know that they are very likely communicating with each other.
>> reporter: researchers also say the abundance of food may explain recent sightings of larger-than-normal groups of whales. earlier this year, a pod of 23 gray whales was spotted near the busy port of los angeles . the biggest group naturalist elisa shulman janiger has ever seen.
>> it was like 4th of july , fireworks popping up around you.
>> reporter: whatever the reasons, the morassis say they feel blessed to have witnessed it.
>> i knew i was seeing something that i'll probably never see again in my life.
>> reporter: front-row seats to a rare natural phenomenon . diana alvear, nbc news, los angeles .