PRODUCERS

A food chain or web shows how energy moves from one group of living things to another. Think of a mouse. A mouse gets the energy it needs from eating grass and seeds. If the mouse is eaten by a snake, its energy moves up the food chain to the snake.

The starting points in any food chain or web are the living things that make their own food. These are called producers. On land, green plants are the main producers.

All the trees and other plants in this forest are made from water, sunlight and a small part of the air.

Green plants make their own food. This process is called photosynthesis. To do this, they need sunlight, the gas carbon dioxide, and water. With the energy from sunlight, plants can combine water and carbon dioxide to make glucose (sugars). The sugars are the plant's food.

Seaweeds are not always green, like land plants. They can be red, or brown like this kelp.

Producers in the Oceans

In the ocean, there are no green plants to make food. Seaweeds such as kelp are one ocean producer. The ocean's main producers are plankton. Plankton are simple creatures that float on ocean currents. They can be plants, animals, or bacteria. Plant plankton is called phytoplankton.

Phytoplankton make food through photosynthesis, like green plants. And like green plants, they need sunlight to make food. So phytoplankton are found close to the ocean surface.

Although tiny, phytoplankton make more food than land plants. Two-thirds of all the photosynthesis on Earth is due to phytoplankton.

Kinds of Plant Plankton

There are many kinds of phytoplankton. The most common are diatoms, blue-green algae, and dinoflagellates.

Diatoms have beautiful clear skeletons. They look as if they are made of glass. They are the most common plankton in cooler seas. Blue-green algae are actually a bacteria. They join together in long strings, sheets, or hollow balls. Large numbers of them can turn the sea blue-green.

Blue-green algae are the oldest of all living things. There have been blue-green algae on Earth for over 3500 million years.

Dinoflagellates are found in tropical waters. They are common around coral reefs. They are also found in freshwater. All dinoflagellates have a long, whiplike “tail.” This is called a flagella. Whipping it from side to side, they move through the water.