This beautiful chart of Key Players in the Food Web makes clear how each kind of marine life interacts with the others.
It was posted in one of the Forums that accompany this MOOC I'm taking. Highly recommended.
This blog records my experiences as a docent at the Piedras Blancas Elephant Seal Rookery on Highway 1 in California. Pups are born during the winter. In February, many are already weaned.