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The importance of predators in ecosystems

Source: http://pixabay.com, licencja: CC 0.

Link to the lesson

Before you start you should know
  • that food taken in by animals provides them with the components vital for the development and proper functioning of the body and the energy necessary for them to carry out their vital activities;

  • that body characteristics and its functions and behaviour are adapted to the life they lead.

You will learn
  • to explain what determines the number of predators and their prey in the ecosystem

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Nagranie abstraktu

The importance of predators in the ecosystem

PredatorspredatorPredators usually choose old or very young individuals as their prey, those who are sick, weakened by parasites or hunger, i.e. those who are easy to catch. Thanks to this, they leave the strongest individuals alive, who will produce healthy and strong offsprings. The elimination of the weakest individuals results in more environmental resources for the remaining strong ones.

Sometimes predators excessively hunt one species. This results in a significant reduction in the number of potential prey. It is becoming increasingly difficult to find them and hunt them down, and many hunting activities fail. As a result, the predator starts to starve. The weakest carnivores die due to lack of food, some are attacked by diseases and parasites, which leads to the decrease in the number of predators. When the number of hunters falls, their prey is safer. It can feed more calmly, reproduce and hence, soon their number increases. This makes prey easily accessible again, often caught by predators, and leads to their proliferation and abundance.

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How predators and prey mutually control each others abundance
Source: Aleksandra Ryczkowska, licencja: CC BY 3.0.
Task 1

Explain why hunters shoot animals such as roe deer, deer, elks and wild boars every year.

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Ilustracja interaktywana przedstawia galerię zdjęć. Na pierwszym zdjęciu widać lochę z małymi dzikami, na drugim zdjęciu stonkę ziemniaczaną na liściu, trzecie zdjęcie przedstawia zająca na trawie. Fotografie podpisano: 1. Boars have few natural enemies and multiply unhinderedly. Some of them approach apartment buildings in search of food. More often we can hear about cases where boars try to force people to feed them. Boars must not be fed, as it teaches them to expect food from people., 2. potato beetle larvae completely destroy potato and tomato plants by feeding on their leaves. The pest is highly resistant to chemicals and has few natural enemies. Predators are deterred by a toxic odourless liquid they produce. Only the pheasant eats the potato beetle larvae willingly, becoming a human ally in the fight against this insect., 3. Rabbits let out free in Australia in the second half of the 19th century, they reproduced on such a scale that they started destroying the plants and soil, leading to an ecological catastrophe. The population of the rabbits was limited by targeted human activities. However, some damages cannot be repaired. The rabbits led to such an inbalance in the local ecosystem, that many of the plants and animals became extinct and others are on the verge of extinction.
Balance between the potential prey and the predator
Source: Filip Dabrowski, JJ Harrison, licencja: CC BY-SA 3.0.
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Exercise 1
Predators play an important role in many ecosystems. What is their role in an ecosystem? Możliwe odpowiedzi: 1. Elimination of all individuals of the species they feed on., 2. Elimination of the weakest, usually old and sick individuals of the species they feed on., 3. Elimination of the strongest and healthiest individuals of the species they feed on., 4. Elimination the resources needed by the species they feed on
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Exercise 2
Arrange the predator and prey control cycle in the right order. Elementy do uszeregowania: 1. an increase in the number of potential prey, 2. frequent successful predator hunting, 3. death of certain predators from hunger and disease, 4. an increase in the number of predators, 5. decline in the number of potential prey, 6. a large number of potential prey

Summary

  • The predators and prey mutually regulate their amount.

Keywords

abundance control, predator, ecosystem

Glossary

predator
predator
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Nagranie słówka: predator

drapieżnik – zwierzę, którego pokarmem są inne zwierzęta, najczęściej stare lub osłabione, które łatwo schwytać