If you’ve ever seen an Eider Duck you may have wondered what they’re doing when they splash their bills in the water. It’s a distinctive thing that they always do. They’ll dive, come up and splash their heads. I finally realised what they’re doing after taking photographs of them.
They dive and find a Shore Crab and then surface. They grab it by a leg and then shake vigorously until the leg is ripped off the body and the remainder of the body is thrown across the water. They then catch it again and rip another leg off until only a limbless body remains.
And then they swallow the body whole.