Do slomo sharks snack on snoozing seals?

This week I wrote a piece for National Geographic News about a study just out suggesting that Greenland sharks could sneak up on seals and catch them while they’re sleeping. It’s a neat study, involving putting motion-sensors on individual sharks to see how fast they swim. In fact, turns out these guys swim so very slowly that they ┬ádidn’t always reach the minumum speed to trigger the tags.

Check out this video from GEERG to see just how slow they swim, even when accompanied by noisy scuba divers. It’s quite soothing to watch these unhurried sharks cruise slowly on by:

[youtube]http://www.youtube.com/watch?v=Hr_t063yVWU[/youtube]

I also spoke with Greg Skomal to get his thoughts on the study. He absolutely agreed that these are immensely slow sharks. He told me how they are essentially neautrally buoyant and can ‘just halt’ in the water column – they can do this because they have this very little calcified cartiladge in their skeletons (you can apparently cut through a Greenland shark skull using a butterknife). So, unlike many other sharks they don’t sink if they stop swimming.

He also told me a story of how he once saw a Greenland shark get its tail caught in a line and even in a state of captive panic, the beast beat its tail at an incredibly slow pace. They truly are sharks in slow motion.

No suprise then, that these slomo sharks are unlikely to be able to catch swimming, wideawake seals. The question still remains if they do in fact eat live seals at all, or just scavenge dead ones.

We need hard, video evidence to prove that one!

Check out more details at my Nat Geo article here.

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