Well, this is a 'crabvalanche' if we've ever seen one – and it was discovered remotely by a postal worker living nearly 1,000 miles from any ocean (hurrah for citizen science!). 

With its high-res live streams, the Ocean Networks Canada (ONC) observatory offers a unique window into life on the ocean floor – not just for researchers, but for anyone interested in taking a dive from the comfort of their computer. Late last month, ONC staff were alerted by one such citizen scientist, a Minnesota postal worker named Michael, who had witnessed something strange. Hundreds (if not thousands, they're still working it out) of grooved tanner crabs (Chionoecetes tanneri) came scuttling through the observatory camera's viewfinder. And the best part? ONC staff had completely missed it! 

According to ONC benthic ecologist Fabio De Leo, there are known periods of time when crabs are more abundant, and even dominate the rest of the fauna in Barkley Canyon, where the footage was captured. But he was amazed to see such large numbers of the grooved tanners. "A closer look at the video reveals that the crabs moved in a single direction, up the canyon toward shallower water depths," he says. "This unidirectional movement suggests that this is not a panic response to a sudden event, where the crabs would likely flee in multiple directions, but rather a mass migration."

With environmental factors ruled out (the observatory station monitors these changes), the team knew where to look for an explanation. Animals tend to migrate in search of three things: climate, food or, the pièce de résistance, sex. Some digging revealed that in March and April, female tanner crabs – which live at deeper depths than males – move to shallow water to mate and lay their eggs.

"Our thanks go to Michael," says the ONC. "Who demonstrated that even when access to the ocean is virtual, ocean discovery is still possible."

Top header image: Neptune Canada/Flickr