Biology
Project:
Gone Fishing
Resources
The ocean is home to a vast number of living things. Just as on land,
these organisms depend on each other for food. Phytoplankton are microscopic
single-celled plants that drift through the water column. Here is what
phytoplankton look like under a microscope. (Click on the images to see
the larger versions.)
 |
 |
 |
 |
Phytoplankton cells have a lot of surface area in relationship to their
volume. This helps phytoplankton remain suspended near the surface where
they can receive sunlight.
Phytoplankton are primary producers as well as the base of the food chain. They can convert the sun's energy into food through the process of photosynthesis. Photosynthesis is the process in plants that transforms radiant energy from sunlight to chemical energy that they can use to grow. Plants make organic substances and release oxygen from CO2 and water when energy from the sun is absorbed in their chlorophyll pigments.
The basic reaction is:
carbon dioxide + water + light energy =
glucose + oxygen + water
Here is a simplified diagram:
Phytoplankton also gather energy from nutrients that are in the sediment on the seafloor. When there is plenty of sunlight and nutrients, phytoplankton multiply rapidly. At certain times, in certain circumstances, a much greater quantity of nutrients than normal reaches the phytoplankton. Usually, this takes place during an upwelling event, when cold, nutrient-rich water flows up to the surface. This results in masses of phytoplankton being produced during a short time. This is called a bloom.
Plankton are the base of the food web. Zooplankton are microscopic animals that live in the ocean. They are the primary consumers that eat the phytoplankton. Small fish, the secondary consumers, eat the zooplankton, which are then eaten by larger organisms (tertiary consumers). A food chain is a simple way to show the relationship that exists among the various plant and animals.
Here is an example of a marine food chain
Most animals eat of variety of food just as you do. A food web is a diagram
that shows how organisms in several different food chains are interconnected.