READ: Predator-Prey

Predator-Prey

Can insects hunt for food? When you think of an animal hunting for its food, large animals such as lions may come to mind. But many tiny animals also hunt for their food. For example, this praying mantis is eating a grasshopper. To eat the grasshopper, the praying mantis first had to catch the grasshopper, which is a form of hunting.

Predation is another mechanism in which species interact with each other. Predation is when a predator organism feeds on another living organism or organisms, known as prey. The predator always lowers the prey’s fitness. It does this by keeping the prey from surviving, reproducing, or both.Predator-prey(relationship where one species, the predator, eats or consumes another species, the prey) relationships are essential to maintaining the balance of organisms in an ecosystem.

There are different types of predation, including:

1. Predation (True Predation)
   
2. Grazing
   
3. Parasitism
   

Predation

Predation is when a predator kills and eats itsprey. Some predators of this type, such as jaguars, kill large prey. They tear it apart and chew it before eating it. Others, like bottlenose dolphins or snakes, may eat their prey whole. In some cases, the prey dies in the mouth or the digestive system of the predator. Baleen whales, for example, eat millions of plankton at once. The prey is digested afterward. Predators may hunt actively for prey, or they may sit and wait for prey to get within striking distance.

This example of a true predator shows a pair of lions actively hunting prey.

Grazing

In grazing, the predator eats part of the prey but does not usually kill it. You may have seen cows grazing on grass. The grass they eat grows back, so there is no real effect on the population. In the ocean, kelp (a type of seaweed) can regrow after being eaten by fish.

The Role of Predators in an Ecosystem

Predators play an important role in an ecosystem. For example, if they did not exist, then a single species could become dominant over others. Grazers on a grassland keep grass from growing out of control. There are species that can have a large effect on the balance of organisms in an ecosystem. For example, if all of the wolves are removed from a population, then the population of deer or rabbits may increase. If there are too many deer, then they may decrease the amount of plants or grasses in the ecosystem. Decreased levels of producers may then have a detrimental effect on the whole ecosystem.

A predator-prey relationship tends to keep the populations of both species in balance. This is shown by the graph in the figure above.  As the prey population increases, there is more food for predators. So, after a slight lag, the predator population increases as well. As the number of predators increases, more prey are captured. As a result, the prey population starts to decrease. What happens to the predator population then?

Summary

• Predation is a relationship in which members of one species (the predator) consume members of another species (the prey).
  
• A predator-prey relationship keeps the populations of both species in balance.