Orca belly-rubbing off Sunshine Coast beach thrills onlookers

Video shows seven killer whales, ranging in size from two to eight metres, scraping bodies up and down the pebbly beach.

Scientists say behaviour is common among northern resident killer whales, but have asked to see video

Scientists say belly rubbing along pebbles is a common behaviour for northern resident killer whales. 0:50

A beach-goer near Sechelt, B.C., has captured a rare sight on video: killer whales rubbing their bodies along a pebbly shoreline.

On Saturday, Martin Michael managed to film a group of seven of the mammals, ranging in size from two to eight metres, in a few metres of water or less.

He said he was amazed by the orcas, which spent about 45 minutes cruising back and forth along the shore at Golden Mile Beach in West Sechelt, which has a steep drop-off.

Martin says a group of seven other people were with him on the beach at the time.

According to the Vancouver Aquarium, the behaviour is fairly common, but unique to northern resident killer whales.

Dr. Lance Barrett-Lennard describes it as a cultural tradition for the whales called beach rubbing.

Michael says since posting the video, he's had researchers contact him to share the video with them.