The food chain has a specific structure. It includes producers, consumers (first, second order, etc.) and reducers. More information about consumers will be described in the article. In order to thoroughly understand who such consumers are of the first order, 2 onwards, we first briefly consider the structure of the food chain.
Food chain structure
As you know, at the first stage of the food chain, or on the first tier of the food pyramid, producers are located. These are plants, the main feature of which is the ability to produce organic from inorganic compounds, which can be assimilated by consumers of the first order during the nutrition process. Due to this feature, they are also called autotrophs (in Greek, self-feeding), in contrast to heterotrophs, which cannot synthesize organic substances. In fairness, it should be noted that they include some representatives of the plant world, mainly parasitic plants. In general, the difference between them can be called quite arbitrary, because there are quite a few types that can use one of the types of food depending on the conditions and situation.
The next link in the chain and, accordingly, the tier of the food pyramid are consumers (of several orders). So called organisms that are consumed by food producers. They will be described in detail below.
And finally, the reducers - the final tier of the food pyramid, the last link in the chain - are the orderlies. It is an integral and very important component of the ecosystem. They process and decompose high molecular weight organic compounds into inorganic ones, which are then reused by autotrophs. Most of them are organisms of rather small sizes: insects, worms, microorganisms, etc.
Who are the consumers?
As mentioned above, consumers are located on the second tier of the food pyramid. These organisms, unlike producers, are not capable of photo- and chemosynthesis (the latter is understood as the process of obtaining energy from carbon dioxide for the synthesis of organic substances by archaea and bacteria). Therefore, they must be fed by other organisms - those who have this ability, or their own kind - other consumers.
Animals - first order consumers
This link of the food chain includes heterotrophs, which, unlike reducers, are not able to decompose organic substances into inorganic ones. The so-called primary consumers (1st order) - those that are directly fed by the biomass producers themselves, that is, producers. These are primarily herbivores - the so-called phytophages.
This group includes both giant mammals, for example elephants, and small insects - locusts, aphids, etc. Examples of first-order consumers are easy to cite. These are almost all animals bred by humans in agriculture: cattle, horses, rabbits, sheep.
Of wild animals, beaver belongs to phytophages. As you know, he uses tree trunks to build dams, and uses their branches for food. Some species of fish, such as grass carp, also belong to herbivores.
Plants - first-order consumers
Interestingly, in this group, scientists include not only those who eat green biomass. To consumers of the first order include parasitic plants. And this is true, because they really eat their brethren, sucking out nutritious juices from them. Examples of such plants are well known to everyone: this is a dodder, popularly called a bindweed. She wraps her long stem around the stem of the producer plant and rises along it in height, eating at his expense. Interestingly, during the evolution of this parasitic plant completely lost the ability to photosynthesis. The stem of the dodder is reddish or brown. He has no roots. Due to the system of haustoria (suction cups), the dodger attaches to the host plant and sucks nutrients from it.
Similarly, parasitic plants of the genus Orobanche (broomrape) are completely devoid of chlorophyll. Their roots are turned into suckers, with which the broomrape is attached to the roots of the host. This plant causes enormous damage to agriculture, as it often parasitizes on leguminous crops cultivated on an industrial scale.
Another example is mistletoe, a well-known and, unfortunately, widespread parasite plant that can be seen on trees. True, in this case, to draw a clear line between producers and consumers is not so easy. Indeed, in parallel with the fact that the mistletoe feeds on the sap of trees, the process of photosynthesis also proceeds in its cells. This is confirmed by the fact that the plant has a green color. But at the same time, mistletoe is also a first-order consumer, because she receives food from other plants.
To summarize, we can draw the following conclusion: consumers are organisms that feed on plants.
Consonants of the second order and further
From the above information, we can already conclude who such consumers are of the 2nd, 3rd, 4th order. This is primarily predatory animals (zoophages) that feed on herbivores (phytophages). This includes the wolf, and the fox, and the lynx, and the lion, and other well-known predators, as well as first-order consumer parasites.
In turn, the 3rd order consumers are those who eat the previous order consumers, that is, larger predators, the 4th are those who eat the third consumers. As a rule, the food pyramid does not exist above the fourth level, since the energy losses from the producer organism to the consumer at the previous levels are quite large. After all, they are inevitable on each of its tiers.
A clear boundary between consumers of certain orders is also often difficult and sometimes impossible to draw. Indeed, some animals are at the same time consumers of different levels.
Also, many of them are omnivorous, for example, a bear, that is, consumers of the first and second order at the same time. The same applies to a person who is omnivorous, although due to different views, traditions or living conditions, for example, he can eat food only of plant origin.
Finally
The article gave a brief description of the food chain (food pyramid) and characterized its main participants. Thus, producers and consumers are present in it - the first two tiers (links). The third - reducers, decomposing organic remains into inorganic ones. We hope that now there are no questions about who the first-order consumers are: these are organisms that receive food directly from producers, eating them or parasitizing them in various ways.