por Predation is an ecological process in which one animal kills or consumes part of the body of another to feed itself, which implies a transfer of energy from the organism that is consumed to the one that is fed. The animal that kills is called the “predator” and the preyed on is known as the “prey”.
Predators are generally the animals with the fewest number of individuals in an ecosystem, since they occupy the upper levels of the food chain. It is also important to point out that predation requires certain specialized biological characteristics, among which physical and behavioral aspects stand out.
Some predators stalk their prey from dark corners until they are within reach; others tirelessly run after their prey until they catch up with them and others simply trick them into catching them.
According to these descriptions, the first images of predators that come to mind are mammals such as lions, wolves or cheetahs stalking deer, antelope or rabbits.
However, there are «big» predators and «small» predators, as it is not a characteristic restricted to mammals: there are insects that prey on other insects and even microorganisms that prey on other microorganisms, that is, there is predation in practically any ecosystem.
Predators are the organisms most sensitive to sudden environmental changes, which is why many conservation campaigns focus on monitoring, protecting, and restoring their populations in each of the ecosystems where they inhabit.
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Predation characteristics
Predation is represented as a kind of competition between two species that are fighting to survive. The prey struggles to escape the predator, while the predator pursues its prey with obsessive interest in order to feed and survive in the ecosystem.
Such competition «shapes» in a relevant way practically all the biological characteristics of a species, which we can classify as:
physical or phenotypic
Predators exhibit special traits and shapes to catch their prey. Predatory animals usually have teeth, claws, large muscles, and impressive hunting abilities. Some produce powerful venoms to kill or immobilize their prey, making it easier to capture.
Prey also have highly developed traits to evade their predators, either to detect them at great distances, to blend in with the landscape, or to flee quickly.
When a predator is after a potential prey, it runs for its food, while the prey runs for its life. If the predator fails, it will go hungry and this can influence all the biological processes in its body, decreasing its chances of reproducing and having young.
If the prey fails to escape, it will lose its life and if it has not reproduced before, it will not pass its genes to the next generation, increasing the variability of the species.
In case it had already reproduced, it will not be able to do it again and its genes will be in a lower proportion in the next generation, in contrast to other individuals of the same species that are more successful escaping from predators.
evolutionary and behavioral
Predatory competition is kept in a constant state of equilibrium, since when one predator or its prey begins to be more successful than the other in competition, said interaction is «self-regulated». For example:
Let’s imagine that predators begin to win the competition and catch their prey with relatively greater ease. If this were the case, the decrease in the number of prey will cause the predators to start a fierce competition among themselves to see who gets which one.
On the other hand, if the prey easily escapes its predators, there will come a point where the prey will be so abundant that the predators will begin to catch it more easily and this will result in the predators reproducing at a higher rate.
All the biological traits that characterize predators and their predators are shaped by processes of natural selection. If the prey does not effectively escape and reproduce constantly, the preyed species will eventually become extinct.
In addition, predators that fail to catch their prey and feed on it will not be able to feed themselves or their young. This translates into a decrease in the number of predators in the ecosystem, which will end with the extinction of the predatory species.
types of predation
Three main types of predation can be identified: carnivory, herbivory and parasitism.
carnivory
Carnivorous predation is the best-known type of predation and involves one animal catching another alive to feed on its body or meat. All predators need to consume the meat or body of their prey in order to survive.
Some species are facultative carnivores, that is, they can eat meat, but it is not essential for their survival. Animals like bears and humans, for example, can survive by eating berries and fruit.
herbivory
Herbivorous predators feed exclusively on plants, algae, and microbes capable of synthesizing their own food (autotrophs). Herbivorous predators are usually the prey of carnivorous predators.
Just as it is true for carnivores, some species of predatory animals are facultative herbivores, that is, they can feed on plants, but also on other animals. This is the case of some cats and bears in South America.
Parasitism
Parasitic predators consume or feed on part of their prey throughout their lives. All parasites live in the body of their prey, so it is said that these are also hosts.
– Parasitoids
They are a group of insects that generally belong to the orders Hymenoptera and Diptera. They are free-living organisms in their adult stage, but during their larval phase they develop inside the eggs of other species.
Inside the egg of the other insect species, which frequently corresponds to butterfly, spider or ant eggs, the parasitoids feed on the juvenile contained therein.
Seen more explicitly: the larva of the parasitoid eats the larva inside the egg, develops to maturity, and hatches out into the environment.
Parasites and parasitoids are not facultative, as they can only survive by permanently feeding on their prey.
In the case of parasitoids, the individual in the adult stage becomes a carnivore and feeds on other insects, although in its larval stage it depends exclusively on its host’s egg.
examples of predation
Carnivores
Wolves and lions are perhaps classic examples of carnivorous predators. They hunt their prey in a pack, focusing on chasing and cornering at least one individual, to attack and seriously injure it with their claws and fangs designed for this purpose.
Once the prey dies, the herd feeds on it to meet its nutritional needs. On many occasions, the prey manages to slip away from its predators and they are forced to retire with empty stomachs until they go hunting again.
herbivores
Herbivores are common in our rural settings: cows, goats, and sheep are all herbivorous animals that feed on grass, weeds, and brush at grazing sites. In that environment they are born, reproduce and die.
However, there are large herbivores that inhabit wild environments: elephants, giraffes, panda bears, among others.
parasitoids
The most common example of parasitoid animals is that of wasps that deposit their larva or their eggs inside the egg of a beetle or butterfly.
The wasp larva feeds on the beetle’s egg and ends up killing it. Once the wasp larva is sufficiently mature, it hatches from the egg and transitions to a free-living stage like its parent.
References
Curio, E. (2012). The ethology of predation (Vol. 7). Springer Science & Business Media. Milinski, M. (1993). Predation risk and feeding behaviour. Behavior of teleost fishes, 285-305. Smith, TM, Smith, RL, & Waters, I. (2012). Elements of ecology. San Francisco: Benjamin Cummings. Stevens, AN (2012). Predation, herbivory, and parasitism. Taylor, R.J. (2013). Predation. Springer Science & Business Media.