Marine biologists study ocean life! Did you know that a large proportion of life on the earth is actually found in the ocean? That might not come as a surprise, considering the majority of the earth’s surface is covered by water. That’s good news for marine biologists because it means there’s so much to study! Marine biologists study all marine life, from tiny microorganisms, to huge blue whales. Marine biologists typically have a master’s degree or a doctorate in marine biology.