The tertiary consumers or third order are the feeding of secondary and primary consumers. For example, carnivores that feed on other carnivores, such as tigers, lions, humans, hyenas, or vultures.
This classification has its origin in what, in biology, is called a food web, which represents all the possible paths that energy and nutrients can take through an ecosystem, jumping from one organism to the next.
Each path is a food chain, and contains several levels that separate different types of organisms. In that sense, a tertiary consumer is one level of a food chain. These can be omnivores or carnivores, meaning that their diets can include plants or consist only of meat.
A good example of a tertiary consumer is a hawk, which can feed on secondary consumers such as snakes or primary consumers such as mice and birds. However, a predator high up in the chain, such as a mountain lion, is still at a higher level than the hawk.
When some organism dies, it is eventually eaten by predators (such as vultures, worms, and crabs) and broken down by decomposers (mostly bacteria and fungi). After this process, the energy exchange still continues.
The position of some organisms in the food chain can vary, as their diet also differs. For example, when a bear eats berries, it is functioning as a primary consumer, but when it eats a herbivorous rodent, it becomes a secondary consumer. Lastly, when the bear eats salmon, it is a tertiary consumer.
Number of tertiary consumers compared to other levels
Tertiary consumers make up the least numerous group within the food pyramid. This is to maintain balance in the flow of energy, which you can see later. In other words, tertiary consumers are the ones that consume the most energy and those that produce the least, therefore their group must be smaller.
In any food web, energy is lost each time one organism eats another. Because of this, there must be many more plants than plant consumers. There are more autotrophs than heterotrophs, and more plant consumers than meat eaters.
Although there is intense competition between animals, there is also interdependence. When a species goes extinct, it can affect a whole chain of species and have unpredictable consequences.
As the number of carnivores in a community increases, they eat more and more herbivores, and thus the herbivore population decreases. Then it becomes more difficult for carnivores to find herbivores to eat, and the carnivore population in turn decreases.
In this way, carnivores and herbivores are kept in a relatively stable equilibrium, each limiting the population of the other. There is a similar balance between plants and plant eaters.
Energy needed by tertiary consumers
Tigers are tertiary consumers
Organisms considered as tertiary consumers require a large amount of energy to be able to nourish themselves and develop their vital functions in a normal way. This is due to the way the energy flow occurs between trophic levels.
Almost all the energy that powers ecosystems ultimately comes from the sun. Solar energy, which is an abiotic factor, enters the ecosystem through the process of photosynthesis. Organisms in an ecosystem that capture electromagnetic energy from the sun and convert it into chemical energy are called producers.
Producers produce the carbon-based molecules, usually carbohydrates, that the rest of the organisms in the ecosystem consume, including humans. These include all green plants, and some bacteria and algae. Every living thing on Earth literally owes its life to the producers.
After a grower captures the sun's energy and has used it to grow plants, other organisms come in and gobble it up. These primary consumers, as they are called, feed exclusively on producers. If these consumers are human, we call them vegetarians. Otherwise, they are known as herbivores.
Primary consumers only get a fraction of the total solar energy, around 10% captured by the producers they eat. The other 90% is used by the producer for growth, reproduction and survival, or is lost as heat.
Primary consumers are consumed by secondary consumers. An example would be insect-eating birds that eat leaves. Secondary consumers are eaten by tertiary consumers. Cats that eat birds that eat insects that eat leaves, for example.
At each level, called the trophic level, about 90% of the energy is lost. Therefore, if a plant captures 1000 calories of solar energy, an insect that eats the plant will only get 100 calories of energy.
A chicken will only get 10 calories, and a human eating the chicken will only get 1 calorie out of the original 1000 calories from solar energy captured by the plant.
The relationships between producers, primary consumers, secondary consumers, and tertiary consumers are often drawn as a pyramid, known as an energy pyramid, with producers at the bottom and tertiary consumers at the top.
Many producers are needed for consumers at higher trophic levels, such as humans, to obtain the energy they need to grow and reproduce. Based on this, it can be said that tertiary consumers are the ones that need the most energy.
This is the answer to the great mystery of why there are so many plants on Earth: because the flow of energy through ecosystems is inefficient. Only 10% of the energy at one trophic level is passed on to the next.
References
- Pyramid of Energy in Ecology (nd). Recovered from kean.edu.
- The ecosystem: an inter-acting community (sf). The Open Door Web Site. Recovered from saburchill.com.
- Food Chain and Food Web (nd). Recovered from ducksters.com.
- Energy: Food Chains (November 2013). Recovered from mrfranta.org.
- Tertiary Consumers and Pelicans. (sf). Welcome To The Marine Biome !!! Recovered from marinebiome2.weebly.com.