Tiny life, ocean-wide connections

Near the sea’s surface, phytoplankton use light energy in photosynthesis to make organic matter. They are the starting point for many marine food chains.

Small, easily overlooked organisms have a large part to play in the ocean’s connections. When learning about marine life, size is only one thing to notice.

Our arrows point from the organism being eaten towards the eater. A feeding connection from phytoplankton to zooplankton and then to fish is an example of a food chain.

Some large fish eat plankton. There is no universal rule that a large fish eats only smaller fish. The dotted line shows that other feeding links are possible.

In the real ocean, one organism may eat several kinds of food and be eaten by several predators. These overlapping relationships form a food web.

Changes in numbers or habitats can affect other organisms. To understand what changes, and by how much, researchers need evidence about the particular species and sea area.