10 Questions Marine Biology: Life in the Ocean Test your knowledge about our watery world with this quiz. Why do most scientists think that life started in the oceans? more animals live in water than on land the oldest fossils ever found show this scientists like to scuba dive What causes ocean tides? the pull of gravity from the Sun the pull of gravity from the Moon the pull of gravity from the Sun and the Moon What is an ecosystem? a system that scientists use to organize their field notes a system that animals use to look after their young a group of organisms that depend on each other and habitat … and 7 more awesome questions! Check them out by clicking “Play”.