Exploring Marine Food Webs with NEPTUNE Canada
Animals need energy every day to survive. This energy comes from food we eat.
Food energy is transfered from one organism to another in what is termed a food chain or food web.
Food chains begin with primary producer organisms that convert non-living molecules into nutrients called sugars or carbohydrates. Plants, phytoplankton, and seaweeds make carbohydrates through the process of photosynthesis, which requires energy from the sun. Other microbes or bacteria make carbohydrates without the sun's energy through a process call chemosynthesis.
Primary producers are the only organisms that can produce carbohydrates and oxygen, and without them there would be no life on earth. The carbohydrates made by the producers are transferred up the good chain to consumers and decomposers. Scientists track the transfer of energy by making models of food chains and food webs.
Below is an energy pyramid showing two simple food chains of life at the Folger Passage life is powered by photosynthesis, and Endeavour Ridge where life is powered by chemosynthesis.
Figure 1. Diagram of an energy pyramid comparing a sunlit Folger Pinnacle community with a deep dark Endeavour Hot Vent community.
Like rungs on a ladder, we classify the steps in the food chain as trophic levels (“trophic” in Greek means food). The pyramid starts with primary producers at its widest point and ends at the narrow top point with carnivores. It takes a lot of producers to fuel the energy for herbivores. As we move up the food chain, the pyramid demonstrates that fewer and fewer animals are supported at each trophic level. This is because lots of food energy is lost between trophic levels for many reasons, including respiration, inefficient digestion and also by waste (did you eat your veggies?).
Explore food webs of each of NEPTUNE Canada's ecosystems:
Ecology Lesson 3: Foodwebs
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