The Burgess Animal Book For Children in "The Mammals Of The Sea"

It is chiefly clams and other shellfish. He rests on floating masses of sea plants. He is very playful and delights to toss pieces of seaweed from paw to paw as he lies floating on his back. Of course he is a wonderful swimmer and diver. Otherwise he couldn't live in the sea.

"Another who comes on land, but only for a very short distance from the water, is called the Walrus.