BlogHop

Location is everything, even when a home is underwater. Mussels (above) that fall into the brine lake or get flooded die quickly. Almost four times as salty as seawater and containing no oxygen, the brine is lethal to most animals. On the other hand, mussels close to the lake benefit from being near the source of methane, which supersaturates the brine under extreme deep-sea pressure. Young mussels crowd the rich inner edge of the colony; empty shells litter the outer fringes. “In the lab you can take this mussels, give it methane, and watch the shell grow, “says Fisher. Yet what seems like simple cause and effect actually involves a unique symbiosis. The mussel doesn’t mainline the methane; bacteria in its gills feed on the gas, and the mussel consumes the bacteria, the bulk of its diet. With a mouth and gut, a seep mussel can also feed like its relatives that live in shallow water-filtering particles of food from water-and may take in vital supplements that way. “When you’re living off one symbiont, you’re in danger of junk-food diet,”says Fisher. The community is a smorgasbord in the desert of the deep. Squat lobsters nip at mussels, snails eat bacteria from shells, and eels feed on whatever they can (above right). A lone fish waits for a meal to swim past (top right).