From bryozoans and snails to shrimps, eels, swordfish, and whales, the Sargasso Sea provides a home to countless types of marine life, thanks to the prevalence of macroalgae called sargassum. Following a single blade of this extraordinary seaweed as it grows and spreads, readers see what it provides for the sea's organisms: a base for hydroids and tube worms to filter and feed, shelter for anemones and nudibranchs and their nutritious waste, hunting...