- What is a food web?
- Aquatic food web
- Terrestrial food web
- Food web and food chain
- Trophic pyramids and their levels
- Desert food web
We explain what a food or food web is, differences with a food chain and its characteristics in terrestrial or aquatic environments.
What is a food web?
It is called a trophic web, food web, or food cycle to the natural interconnection of all the food chains belonging to a ecological community. It is generally represented visually, like a network or also a pyramid.
Let us remember that these food chains describe linearly the way in which the matter and the Energy spend about living beings to others within a habitat specific. In other words, the sum of all the Trophic chains of a ecosystem will result in your food web.
The trophic relationships between various life forms are understood on the basis of a primary and fundamental distinction between the organisms:
- Autotrophic organisms. They are able to synthesize their nutrients from inorganic material.
- Heterotrophic organisms. They are incapable of such synthesis and are therefore obliged to consume the organic material of other living beings, either autotrophs or heterotrophs in turn.
Each of these categories makes up a trophic level, in which all living beings can be classified. However, heterotrophic organisms or consumers are subdivided into different groups in turn, depending on what strategies set in motion to consume the organic matter of others living beings and what kind of living things they usually feed on.
In other words, among the heterotrophs there are:
- Herbivores or primary consumers. They feed on plants and other autotrophic beings.
- Carnivores or secondary consumers. They eat herbivores.
- Predators or tertiary consumers. They feed on both primary and secondary.
- Decomposing organisms. Are heterotrophs Also, but they feed on decomposing organic matter, that is, dead.
All this classification is contemplated in the trophic networks, an ecological perspective that the English zoologist Charles Elton inaugurated with his text Animal ecology , first attempt to organize living beings into functional groups according to their way of nourishing themselves.
Then the contributions on the matter by Raymond Lindeman were added, insisting on the vital role of decomposers in the ecological circuit. All of this is vital for the understanding that we currently have of the way in which matter and energy are transmitted along the food webs of an ecosystem.
Aquatic food web
In the aquatic ecosystems, food webs are fully adapted to life in, under, and on the surface of the water. This applies to large bodies of water such as oceans, lakes and other deposits of Water.
Aquatic food chains usually start in algae and certain types of photosynthetic microorganisms that float on the surface, called phytoplankton, and who play the role of autotrophic producers.
Primary consumers feed on them, generally others microorganisms (zooplankton) or crustaceans tiny, if not small fish, sponges or other forms of life simple.
The next link involves larger fish, jellyfish and other very firsts. predators. The third link of consumers shows already good-sized fish, and even some final predators.
These chains must include actors that feed on the sea, but they do not live in it, like seabirds (such as pelicans) capable of fishing from shoals on the surface.
Also involved in food webs are mammals marine (seals, walruses, whales) that usually act as final predators (except in the case of the seal, a favorite prey of the orca whale and certain sharks). In lakes, rivers or certain islands, they also participate amphibians Y reptiles, as active predators depending on their size (such as crocodiles).
Likewise, the decomposers of the sea are legion. Carrion crustaceans, tiny fish and various types of microorganisms take over the organic matter left over from the hunts, which in turn constitutes a rain of food for the deepest and darkest regions of the sea.
Terrestrial food web
In the terrestrial ecosystems, trophic webs are even more extensive than marine webs, since they involve a gigantic variety of autotrophic organisms (plants).
As a consequence, there is a wide diversity of primary consumers: from insects that feed on sap or nectar, through fruit-eating birds and ruminant herbivores of varying volume, to symbiotic and decomposing fungi, leaf-eating insects and a huge etcetera.
Likewise, such a variety of herbivores supports an equally diversified number of secondary consumers, including especially small rodents, some primates and arthropods like the spider.
Tertiary consumers, larger in size and with a carnivorous appetite, also depend on them, such as big hunting cats, bears, lizards, birds of prey, higher primates and, of course, the human being.
The most common decomposers are bacteria and other microorganisms, as well as fungi, scavengers or larvae of various kinds.
Food web and food chain
The difference between food webs and food chains is subtle: the sum of the food chains in an ecosystem will result in a food web. The trophic chains are linear, generally involving a single species from each food rung.
On the other hand, networks try to combine them all to establish a map of how matter flows within the set of trophic relationships in a given place. That is why networks are more complex, more abundant, and more difficult to graph and conceive.
Trophic pyramids and their levels
The functional groups listed so far (producers, primary, secondary and tertiary consumers, decomposers) that make up all the food chains and networks can be visually organized based on the abundance criterion of each group.
That is, the further away you are from the producer organisms, the less abundant life tends to be, since the energy and nutritional requirements tend to be higher, due to having larger species. In this way, food chains and webs can be illustrated in the form of a pyramid: the trophic pyramid.
The pyramid will be divided into levels, each corresponding to a trophic link, having at the base the decomposers, and together with them the producers, forming the base of the pyramid: abundant and primary, they do not depend on any link, but they support those above.
On the producers will be the primary or herbivorous consumers, and on them the secondary and tertiary consumers, with as many levels as necessary, as we tend to larger species, greater appetite, but at the same time less abundance, which is represented in the narrowing of the pyramid towards its tip.
Thus, for example, the final predators, located at the very top of the pyramid, will not have anything above, but will depend nutritionally on all the lower levels. However, it is important to remember that they also serve as food for decomposers.
Desert food web
The desert it is an intense ecosystem, of life adapted to withstand the brutal temperatures daily and the terrible drought, which is a challenge given that there is scarce vegetation in these places, designed to withstand a long time without water or to capture it from the air, and therefore a very low rate of biodiversity.
However, in the desert it is possible to find all the trophic levels of a pyramid: the producers, among whom will be xerophytic plants, such as cacti, never too numerous, unlike other ecosystems.
Instead, decomposers are much more abundant compared to the other levels: insects, scavengers and microorganisms, since in the desert the intense conditions mean that nothing is wasted.
On the basis of these decomposers, rather than plants, the rest of the food web is sustained. In it are small primary consumers, mostly insects and some small rodents.
They feed on hunting arthropods (such as scorpions), poisonous snakes or some small birds. And finally there is a third link of consumers constituted by prey birds, snakes of good size or some canids like the coyote, depending on the location and the type of desert.