changes to food webs

• • All organisms in a food web depend upon each other and changes to one can affect the others.
• • Predator-prey cycles show the natural rise and fall of numbers of predators and prey over time.
• predators have adaptations to help catch prey e.g. fox has good hearing
• prey have adaptations to escape predator e.g. rabbit has good eyesight
• adaptations:

  Prey have adaptations to avoid being hunted, such as good hearing or eyes on the sides of their heads for a wide field of vision. This means it’s easier for them to see predators coming. Prey often have very good camouflage to avoid being seen

  Predators have adaptations to hunt effectively like sharp claws and teeth, with eyes at the front of their heads to judge distances well. Some predators, for example cheetahs, can run very fast for short distances. Wolves can run great distances over longer periods of time, until their prey run out of energy.
• Food webs are able to flex and quickly bounce back to small changes in numbers. However big changes are more difficult for food webs to stabilise. These large changes are often due to human activity, such as deforestation, constructing roads and buildings, and the use of chemical pesticides.
• food security:

  All the food we eat relies on plants. This includes meat because animals such as pigs, sheep and cattle eat plants. Grasses such as wheat, barley and rice use the wind for pollination. Plants that produce fruit rely on insects and other animals for their pollination.

  If the population of pollinating insects goes down, it reduces the amount of these plants for us to eat, and also the number of seeds for new plants to grow. Food security means having a reliable source of nutritious food.