Swimming Ahead

Earth Almanac

by Ted Williams

After summer warms earth's temperate seas, look for a towering fin flopping back and forth in near-shore waters. It belongs not to a shark but to the ocean sunfish (Mola mola), earth's largest bony fish, which is taller than it is long and weighs as much as 5,000 pounds. Propelled by dorsal and anal fins, and steered by its nearly nonexistent tail, the ocean sunfish seems to be all head. If you're lucky enough to encounter one, it will most likely be basking, often lying on its side as if sick. If you approach quietly and slowly, you can sometimes reach down and stroke its rough hide, which may have seaweedlike parasites sprouting from it. Ocean sunfish appear to invite seabirds and fish such as wrasse to pick the prolific parasites from their gills, fins, and flanks, rolling over when they fancy that one side has been sufficiently cleaned. Ocean sunfish suck in food through their toothy beaks, spit it out, suck it in, spit it out, and so on, until the pieces are small enough to swallow. They have a varied diet that includes eelgrass, mollusks, jellyfish, salps, algae, plankton, and small fishes.

--from Audubon magazine