Sion Chun
Bio I
9/21/10
Trophic Pyramids
Trophic pyramids, in other words, ecological pyramids, have three types described in
specific subject within trophic levels. In definition, trophic level is defined as a step in a food
chain or web, basically primary producer at the bottom and first, second, and third-level
consumers in order, and ecological pyramid is a description of amount of energy or matter. And
there are total three distinct types of ecological pyramids: energy, biomass, and numbers
pyramids. All of them shape pyramids, since any ecological pyramids get narrower as trophic
level goes higher towards third-level consumer from primary producer.
First pyramid shows energy on each trophic level. Primary producer represents its energy
is transferred into next trophic level, which is first-level consumer. Then, in the same way,
second-level takes first-level consumers’ energy, and vice versa for third-level consumers. And
there is an important statistic that, on average, only 10 percent of energy can be taken over from.
For instance, after primary producer, such as leaves, achieve energy from light or chemical
energy, if first-level consumer takes its energy, the taker would attain only one tenth of the
energy that it originally had. Therefore, the pyramid of energy shapes a pyramid, because energy
decreases as each trophic level gets higher.
Other two types are pyramids of biomass and numbers. Biomass and numbers are amount
of living tissue and numbers in a trophic level. Because numbers of organisms in higher trophic
level is mostly less than those of below levels, it forms a pyramid. Similarly, since lower level of
pyramid has more numbers, it normally has larger sum of amount of matter than its higher level
does, which outcomes the both types forming in pyramids.