(MONEY Magazine) – At a dock in Marina del Rey, near Los Angeles, stands an 85-foot-long, three- deck ship loaded with ocean-monitoring equipment. Lily Lam visited Ann Dalkey, a marine biologist, and Ioannice (pronounced ee-oh-neece) Lee, a water microbiologist, on board the ship to learn more about what a marine biologist does. (In the picture, Lily is leaning on Ioannice; Ann is in the background.)

Marine biologists study animals that live in the ocean. Their work can range from studying how starfish grow new arms to seeing how pollution affects marine life. Microbiologists study microorganisms, which are living things so small that they can be seen only under a microscope. Bacteria are microorganisms that can cause diseases. Ann and Ioannice work for the City of Los Angeles to help keep the Pacific Ocean clean. Every day, people in L.A. produce as much as 360 million gallons of dirty water -- from washing dishes, flushing toilets or taking showers. The water goes to the Hyperion Treatment Plant in nearby Playa del Rey. It is filtered and cleaned with chemicals -- but some pollution does remain. It is piped into Santa Monica Bay and flows out to the Pacific Ocean. Twice a week, the ship sails into the bay. Ann studies samples of water and mud to see how the marine animals are surviving. Ioannice studies water samples for bacteria that could hurt people. On the ship, Ann showed Lily around. Lily saw a scientific instrument called a water-quality analyzer and the ship's small laboratory. Later on, Lily, Ann and Ioannice went to the marine biology laboratory at the Hyperion plant. Ann showed Lily a mud sample from near the pipe that brings the treated water into the bay and a sample from out at sea. The sample from near the pipe was so polluted that only worms could live in it. Lily told Ann and Ioannice she had been on a ship only once before -- a small sailboat. She said it was interesting to learn about marine biology but being on the ship had been ''really fun.''