Orcas, more than sharks, are atop the marine food chain, and that became strikingly apparent this week at Blue Cliffs Beach off New Zealand, where at least one orca mounted a prolonged assaulted on sharks in the surf zone, as witnesses watched in amazement (see video).



[Related: record gray whale sightings off the coast of Southern California.]

The video clip shows what appears to be a male orca, or killer whale, fiercely harassing a shark near the small breakers, and a large shark beaching itself, perhaps in an attempt to escape the orca, only to be harassed by a barking dog.

[Big-wave surfer tests life saving wetsuit in massive surf.]

The entire episode lasted about two hours and Clinton Duffy, of the New Zealand Conservation Marine Institute, explained that there probably were several orcas taking part. He added that the killer whales sometimes enter the surf zone to herd fish farther offshore. The sharks, clearly, were in the wrong place at the wrong time.

This is not the first time orcas have been documented attacking sharks. Perhaps the most notable event was in 1997 west of San Francisco, Calif., when an orca killed a 12-foot great white shark in what appeared to have been a one-sided battle. And yes, footage of that encounter went viral.

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