What is a secondary consumer?
A secondary consumer is an animal that is primarily a carnivore (carnivores are animals that eat flesh) that preys on primary consumers or herbivores. Other examples of secondary consumers are omnivores (omnivores consume both plant and animal matter) that eat both primary consumers and primary producers or autotrophs. In the food chain, the secondary consumers occupy the third trophic level.
Secondary consumer definition
A secondary consumer is an organism or group of organisms that feed on primary consumers (herbivores) to obtain the needed energy for their survival. For example, a deer which is a herbivore is fed upon by a lion or a hyena which is a secondary consumer. To survive, almost every secondary consumer, whether omnivores or carnivores, must consume the primary producers and the primary consumers via a heterotrophic mode of nutrition (heterotrophic mode of nutrition refers to a mode of feeding where an animal feeds on multiple sources of food such as a secondary consumer consuming other organisms such as plants and animals).
Secondary consumers have evolved to thrive in a variety of ecosystems, whether, in a terrestrial or aquatic environment, and the only thing they have in common is the type of food they eat which are primary consumers and primary producers.
Types of secondary consumers
Carnivores are animal species that feed mainly on the meat of other animals. For example, snakes, seals, spiders, lizards, mice, and fish are a few examples of secondary consumers that are carnivorous in nature. In their pursuit of obtaining energy, some secondary consumers, be it a large or a small predator prefer to consume larger and bigger prey (herbivores) than themselves in order to complement the energy lost during the chase.
The other type of secondary consumer is the omnivore and they consume both plant and animal materials to obtain energy. For example, skunks and bears are found in this category of omnivorous secondary consumers, which hunt prey as well as consume plants. Some omnivores are merely scavengers i.e. instead of hunting, they eat the excess animal remains left by other predators; examples of animals that scavenge for food include opossums, vultures, and hyenas.
Classification of Secondary Consumers
- Aquatic secondary consumer
- Terrestrial secondary consumer
Aquatic secondary consumers
Massive amounts of food can be found in aquatic environments providing a wide range of secondary consumers to feed on these huge quantities of food in the food chain. A good example of a secondary consumer is an aquatic omnivore known as the piranha. The piranha is a secondary consumer that feeds on fish, birds, snails, and aquatic plants. Other examples of secondary consumers in the ocean include smaller, less predatory sharks that feed on fishes in the second trophic level.
The presence of aquatic secondary consumers is critical for population control of primary consumers, otherwise, the population of the primary consumers would become uncontrollable, resulting in excessive consumption of ecosystem producers. That is, there would be no life on Earth if these primary producers and other similar autotrophs did not exist.
Terrestrial secondary consumers
Terrestrial ecosystems or environments span from freezing habitats with negative temperatures to deserts with no water near the equator. Secondary consumers have certain adaptative characteristics that allow them to survive in a variety of terrestrial ecosystems, for example, dogs, cats, owls, snakes, moles, and birds, can be found in temperate regions and these secondary consumers kill and source for their own food whereas other secondary consumers such as wolves, crows, and hawks, found in cold regions obtain their energy from primary consumers by scavenging.
As stated earlier, depending on the environment, secondary consumers can also be classified as primary consumers. In this case, a squirrel is a good example, because it consumes nuts and fruits on certain occasions, making it a primary consumer. The squirrel may start eating insects and thus become a secondary consumer and this type of switching can occur at any time and in any location, depending on food and predators in the environment.
Examples of animals that are secondary consumers in a food chain
The above listed are the secondary consumer animals found in both terrestrial and aquatic ecosystems.
List of secondary consumers in the ocean
- Carnivorous fish
- Sea stars
Functions of a secondary consumer
Secondary consumers play an important role in the food chain as they aid in the regulation of the populations of primary consumers in an ecosystem. They do so by feeding on the primary consumers in the food chain for energy. Secondary consumers also provide nutrients and energy to tertiary consumers when tertiary consumers in the food web feed on them.
Consumers are classified into trophic levels, with energy flowing from the bottom to the top of the trophic level. In order to understand the function of the secondary consumer, a summary of the trophic levels will be given starting with the primary producers. Primary producers or autotrophic plants occupy the lowest trophic level also known as the first trophic level in the food chain because of their ability to generate their own energy through the process of photosynthesis. The second trophic level in the food web is occupied by the primary consumers, followed by the occupation of the third trophic level by the secondary consumers. The fourth trophic level is occupied by the tertiary consumers.
Now that the occupants of the various trophic levels in the food web have been identified, a further breakdown of the energy transfer will be subsequently discussed.
It has been observed that up to 90% of energy is lost during the transfer of energy from one trophic level to the next. That means that only 10% of the energy is transferred to the next trophic level and this 10% is typically stored as flesh before being transported to the animal in the next tropical level. While self-sustaining organisms generate 100% of their own energy, a secondary consumer receives only 1% of the original energy generated in the food chain and high-level consumers receive even less energy. This explains why food chains rarely exceed five trophic levels.
Because of this energy loss, higher-level consumers must consume more food, and as a result, there must be more primary producers and consumers of plants than any other type of organism. This ensures that there is enough energy for the higher trophic levels. However, just because fewer secondary consumers are required in an ecosystem does not imply that they are any less important. Their presence is critical to the food chain’s balance, if not, tertiary consumers would go hungry if there were not enough secondary consumers in a food chain due to lack of food resources, and they may even become extinct. The case of an overabundance of secondary consumers will lead to an overconsumption of primary consumers to the point of extinction.
Both scenarios where there is a low populace of secondary consumers and a high populace of primary consumers would upset the ecosystem’s natural balance. In light of this, there must be more plants than plant consumers and more secondary consumers that feed on the plant-eaters.
Aside from the intense competition between animals, they are also interdependent associations amongst the animals that help to balance the whole food chain. Because, when an organism is wiped out, it can have far-reaching consequences for a whole chain of other organisms.
Importance of a secondary consumer
- It provides a balance in the ecosystem by preventing the overpopulation of primary consumers.
- It also provides energy to other members of the tertiary consumers in the fourth trophic level of the food chain. This is because secondary consumers are eaten by larger animals in the food chain.
Difference between primary and secondary consumers
|Primary consumers||Secondary consumers|
|They feed on autotrophs (primary producers or plants)||Secondary consumers feed on primary consumers.|
|Primary consumers are generally herbivores||They are either carnivores or omnivores|
|They occupy the second trophic level in the food chain||Members of this group occupy the third trophic level in the food chain.|
|Examples of primary consumers include; rabbits, grasshoppers, insect larvae, crabs, and cows.||Secondary consumers examples include; frogs, mice, hyenas, lions, and piranhas.|
Is a frog a secondary consumer?
Yes, because frogs feed on insect larvae and insects that feed on plants. This means they eat the next organisms in the food web.
Is a mouse a secondary consumer?
Yes, and this is because a mouse feed on grasshoppers, and grasshoppers occupy the second trophic level while a mouse occupies the third trophic level.