Well it depends on what type of place your talking about such as rainforest's, etc. Most animals decrease on the food chain because of either the extinction, or because they cant survive either through weather or because of a little limit on food.
it is 10% of the animal population below it because of the 10 % rule
evolution
Shows the relative number of individual organisms at each trophic level.
domain
ecological pyramid
Not all organisms have the same mass. Consider 1 whale versus 5,000 plankton - the whale has much greater mass, but only 0.1% of the total number of organisms. When you compare mass, you get a better idea of how much energy is actually available at that trophic level. Basically, they are better to understand.
The biomass of each organism decreases with each level. With less energy at higher trophic levels, there are usually fewer organisms as well. Organisms tend to be larger in size at higher trophic levels, but their smaller numbers result in less biomass. Biomass is the total mass of organisms at a trophic level.
Shows the relative number of individual organisms at each trophic level.
domain
It used by the organisms at each trophic level to keep themselves alive.
evolution
Biomass pyramids show how much biomass is present in the organisms at each trophic level. A pyramid of numbers does not deal with living organisms. Source: chacha.com This, again, is my brainless answer! However, please take it seriously, for I found it in a real website this time. -_-
ecological pyramid
Not all organisms have the same mass. Consider 1 whale versus 5,000 plankton - the whale has much greater mass, but only 0.1% of the total number of organisms. When you compare mass, you get a better idea of how much energy is actually available at that trophic level. Basically, they are better to understand.
For a food chain it means that every organism within an ecosystem provides energy for other organisms and food chains are a way of showing a step by step sequence of who eats whom in an ecosystem. Pyramid of numbers can ve drwn by counting the number of organisms at each trophic level in an ecosystem. When these numbers are then represented on a vertical graph, with the volume of each level representing the number of organisms at that level, the graph sometimes takes on a the general shape of a pyramid.
A pyramid of numbers will only tell you the amount of organisms at each trophic level. A Biomass pyramid ignores the amount of organisms in favour of their biomass (dry weight) which in turn represents the amount of energy available at each trophic level.
The number of organisms increases as you go up each classification level. Domain- largest and most inclusive category Kingdom Phylum Class Order Family Genus Species
An ecological pyramid is simply a graphical representation of the relationship at each trophic level in a particular ecosystem. There are three types of ecological pyramids: of numbers, of energy, and of biomass. For example the pyramid of numbers is a representation of the number of organisms in each trophic level, with herbivores at the bottom as primary consumers, followed by first level carnivores and so on.
The first of the four, is the ecological pyramid. It shows the number of organisms in each of the trophic levels in an ecosystem. At the base of the levels are the producers and at the top of the pyramid are the final consumers. The second is the number pyramid. This also shows the number of organisms in each of the trophic levels but it does not take into consideration the size of each of the organism in the levels. This pyramid has four levels, starting from the bottom is the total number of producers, then the total number of herbivores, third the total number of small carnivores, and finally the total number of large carnivores. The third pyramid is the biomass pyramid. This pyramid is an indication of the total mass of organisms in the trophic levels. There are three levels of biomass in this pyramid. These are producers ( 470.0 g/m2), then herbivores (0.6 g/m2), and last the carnivores ( 0.1 g/m2). And it is possible for the second level to be greater than the third. Last, is the energy pyramid which indicates the total amount of energy that is in the trophic levels. It also is able to show the loss of energy between the trophic levels. The four levels in this pyramid are Producers, Primary consumers, Secondary consumers and at the top are the Tertiary consumers. As energy passes between the levels, such as from producers to primary consumers, much of the energy is lost due to waste and the conversion to heat energy.