Trophic Pyramid
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One the video to the left, a trophic pyramid of the Sonoran Desert in Arizona, is shown. At the bottom are the producers (catclaw tree, a shrub, grass plants), in the middle are the consumers (jackrabbit and mule deer), and at the top is our top predator (the cougar). As each thing is consumed, less energy travels up the pyramid (90% is lost, while the other 10% is eaten/consumed). Also, at the bottom of the pyramid, there are more of that kind than there are of the organisms that get closer to the top. After anything in that pyramid dies, it's body is decomposed and the energy it has left goes to the decomposers (mycena mushrooms, insects/stinkbugs).
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Food Web
The image on the left shows a food web of the Sonoran Desert for the apex predator: The cougar (otherwise known as a mountain lion). First off, let's start with the producers. Here, it shows the producers as trees and grass. In the trophic pyramid shown above, I use cat claw trees, in particular. But for now, let's just refer to them as trees. We can see that the primary consumers would be the deer, the rabbit, the mouse, and the cricket. The secondary consumers would be the frog, the hawk, the cougar, and the snake. The tertiary consumer would the hawk, and the predators would be the cougar, and, again, the hawk.
First, let's take a look at the chain with trees as it's producer. It is shown that the deer (primary consumer) than eats the trees, and the cougar (secondary consumer/apex predator) eats the deer. The second chain we'll look at starts off with grass as it's producer. The rabbit (primary consumer) then eats the grass, and gets eaten by either the hawk or the cougar (secondary consumers/apex predators). Next, the mouse (primary consumer) eats the grass, but then gets eaten by the snake (tertiary consumer), or directly by the hawk (which can also eat the snake; secondary consumer/apex predator). Our last chain will be the cricket (primary consumer) which eats the grass, and then gets eaten by the frog (secondary consumer). Finally, the frog is eaten by the hawk (tertiary consumer/apex predator). |
Limiting Factors & Carrying Capacity
Carrying capacity is when an area is able to hold only a certain amount of cougars. The cause of this are the limiting factors that restrict the population of this animal, in it's ecosystem. Some of the factors would be:
Speaking of food availability, this is how the number of cougars in an ecosystem can waver. If there are too many cougars, food will start to decrease, and when there isn't much food left, the number of cougars will also decrease. When this happens, food will start to increase, which lets the surviving cougars have more to eat. |