Mr. Seaborg continues his survey of ecologies on planet Earth, this time focusing on life in the sea. Fewer species live in our seas than on land. Why that’s so, rooted in matters of depth, salinity, light penetration, and chemistry, is an important part of the story. But that doesn’t mean there’s not lots of life to be discovered in the world’s oceans, and it offers many challenges for us to understand how it evolved and continues to exist. Let OLLI and Mr. Seaborg give you a fresh look at the intriguing communities of life, existing from the surfaces to the depths of our planet’s seas.