What do you know about energy pyramids and the tropical rainforest? In this lesson, you will learn what an energy pyramid is as well as what the energy pyramid of a tropical rainforest looks like.
On the Hunt
The jaguar has been quietly watching the group of deer feeding in the forest. He has especially been watching a slow and curious straggler that keeps wandering off from the rest of the group. Once the sky is pitch black, it will be time to strike. Another 30 minutes should do it.
While he watches and waits, he plans his attack. As it gets darker, the deer start to retreat to a safer spot, however the straggler is slow to move. Now is his chance. The jaguar quietly stalks his prey. Before the deer knew what happened, the jaguar pounces on him.
The jaguar is lucky that tonight he gets a meal and that all his planning and effort paid off, since this is not always the case.
An Expensive Meal
The jaguar, a resident of the tropical rainforest, was described as lucky in the introductory paragraph. He was described that way because he did a lot of planning, watching and stalking of the deer he was able to capture. Sometimes, the large amount of energy put into capturing prey pays off, and sometimes it doesn’t. However, meals are not only expensive for the jaguar in the tropical rainforest. All naturally-obtained meals are just as expensive for every organism in the rainforest.Most Americans, are used to getting their food from the supermarket.
Most humans no longer have to hunt for their food. In the natural environment, the process is not so simple. A monkey can’t go to the produce aisle and pick up a pound of bananas.
Monkeys in the tropical rainforest have to swing from tree to tree looking for bananas, expending energy. This is like what the jaguar had to do. Both the monkey and the jaguar expend quite a bit of energy to get a small return. Both organisms eat very expensive meals.
The 10% Rule
The10% Rule states that only ten percent of the energy contained is transferred from one trophic level to the next. For example, lets think about the jaguar.
The jaguar was able to accomplish his goal of capturing the deer. The deer did not know he was going to be the jaguar’s dinner that night, so he spent quite a bit of time grazing that day. While grazing, the deer was expending energy. So, all of the energy that was once contained in the deer, was not given to the jaguar, some of the deer’s energy was used to graze, jump, run and even sleep.
In addition, the jaguar had to watch, stalk and pounce on the deer, he also expended energy. A lot of the energy the jaguar expended took place before he even got the chance to eat the deer, not counting the energy it took to eat and digest it. After all of the effort put into obtaining his meal, the jaguar only ended up with a ten percent energy transfer from the deer.
Energy Pyramids & Trophic Levels of the Rainforest
An energy pyramid illustrates the trophic levels of organisms in an ecosystem and gives a visual representation of energy loss at each level. The energy pyramid effectively demonstrates the 10% Rule.
All energy pyramids start with the sun as the source of all energy, followed by the trophic levels, producers (plants) on the bottom, primary consumers (herbivores) at the next level up, then secondary consumers (eat plants and meat) and then tertiary consumers (meat eaters) at the top.Again, as you move from the sun through each trophic level, only ten percent of the energy will be carried to the next level.
Each organism uses some of what it obtains for its life processes, so the organism that eats it can only use the energy that is left over. The organism that eats the one at the level below it also has to expend some energy to get the food, thus continuing the pattern. Look at the examples of an energy pyramid. The examples show that as you start with the producers and move up the pyramid, the amount of available energy lessens.
The 10% Rule states that only ten percent of the energy contained is transferred from one trophic level to the next.
An energy pyramid illustrates the trophic levels of organisms in an ecosystem. Energy pyramids start with the sun, followed by the trophic levels: producers (plants) on the bottom, primary consumers (herbivores) next, then secondary consumers (eat plants and meat) and then tertiary consumers (meat eaters) at the top.