CHAPTER 5 1 TROPHIC PYRAMIDS FOOD CHAINS ITS

CHAPTER 5. 1 TROPHIC PYRAMIDS

FOOD CHAINS: IT’S ALL ABOUT ENERGY FLOW Some energy is lost as heat with every step of the food chain

TROPHIC PYRAMIDS: We can represent information about trophic relationships by diagrams called trophic pyramids – three types: 1. Pyramid of energy 2. Pyramid of biomass 3. Pyramid of numbers

PYRAMID OF ENERGY • Only about 10% of the energy available at one trophic level is passed on to the next • Also known as the 10% Rule • Remember, some energy is: • lost as heat • some energy is used to carry out cellular processes • some energy is used for reproduction

PYRAMID OF ENERGY OR “ 10% RULE” Therefore, not all calories consumed go to make up the organism’s body (meal for next level) Always will be an upright pyramidal shape

PYRAMID OF NUMBERS Due to the loss of energy with each trophic level, there are fewer and fewer individuals as you go up the food chain. We can represent this with a pyramid of numbers….

PYRAMID OF NUMBERS

PYRAMID OF BIOMASS Biomass is defined as the amount of mass of living things in a given area. We can measure the biomass of producers, the biomass of primary consumers, etc. There is more biomass of plants than primary consumers, and more of primary consumers than secondary consumers, etc. Biomass of plants>biomass of grasshoppers>biomass of birds Then we can make another pyramid to represent this information….

PYRAMID OF BIOMASS

TROPHIC PYRAMIDS EXPLAIN THREE CONCEPTS… 1. They show why there are usually only four or five trophic levels in a food chain 2. They show why there are so few large top predators 3. They show why the earth can support more people if they eat at lower trophic levels (eat less meat)