Producers and consumers

• Feeding relationships show what organisms eat or are eaten by others and through this the levels of organisation in an ecosystem. These can be shown in food chains, which add together to make food webs for a habitat.
• A simple example of a food chain is:

  grass → rabbits → foxes
• At the base of almost every food chain is a producer. These are plants or algae, which photosynthesise. This means they convert energy from the sun into glucose during photosynthesis producing biomass. It is this which feeds the rest of the food chain.
• All animals above the producer are called consumers. The first is the primary consumer, the next is the secondary consumer. Animals that hunt and kill others are called predators, and those that are hunted and killed are called prey. The top animal in the feeding relationship is called the apex predator.
• Decomposers are bacteria and fungi, which break down dead organisms in a process called decomposition or rotting. They do this by releasing enzymes onto the dead matter and afterwards, consume the broken down substances. They form a vital role in the recycling of matter. When organisms die and decompose plants absorb the broken down nutrients through their roots.
• 1. the number of predators increases because there is more prey
  2. the number of prey reduces because there are more predators
  3. the number of predators reduces because there is less prey
• In a healthy, balanced ecosystem the numbers of predators and prey remain fairly constant. They can go up and down during each year but generally over the years, these increases and decreases remain fairly constant.
• If numbers of either predators or prey increase or decrease it could be due to a change in the abiotic factors, like water or sunlight, or biotic factors, like a new predator or pathogen. This would result in a less healthy, balanced ecosystem.