WHAT IS AN ECOSYSTEM? DO YOU REMEMBER IT?
An ecosystem is made up of living things and the physical environment, where they live. Living things are affected by different factors in the environment, for example, temperature and light. Ecosystems can be terrestrial, like forests and deserts, or aquatic, like seas and rivers.
INTERRALIONSHIPS IN ECOSYSTEMS
Living things are affected by different factors in the environment. Some factors have a greater influence on living things. For example, water is essential for living things in terrestrial environments. However, it is usually a combination of factors that determines which living things can survive in a particular place.
- In terrestrial ecosystems, the main factors are temperature, humidity, type of soil and light.
- In aquatic ecosystems, the main factors are temperature, water currents, light and salt content.
Living things can also modify the environment. For example, beavers cut down trees and use them to build dams.
The components of an ecosystem are in balance with each other.
ADAPTATION TO THE ENVIRONMENT
Living things have different needs, and they live in places where they can satisfy these needs. For example, frogs need to live near water. An area where a living thing lives and can fin everything it needs is its habitat.
Species also adapt to their environment. Adaptation allows living things to survive in a particular environment. For example:
- Plants in dry climates have adapted to be efficient with water. These plants can have small leaves, a waxy surface or leaf hairs to reduce water loss. They can also have deep roots to increase the water they take in.
- Polar bears have paws which help them to swim and to walk on ice. Their fur and a thick layer of fat provide them with insulation against the cold.
NUTRITION IN ECOSYSTEM
All living things need food to survive. Depending on how living things obtain their food, they can be producers, consumers or decomposers.
- PRODUCERS: are living things that make their own food. For example: plants.
- CONSUMERS: obtain their food from other living things. There are two types:
- PRIMARY CONSUMERS: they eat producers, so they are herbivores. For example: rabbits, zebra...
- SECONDARY CONSUMERS: they eat primary consumers, so they are carnivores. For example: fox, lion...
- DECOMPOSERS: they eat the remains of dead animals. Decomposers are microorganisms and fungi that break down dead animal and plant materials. They decompose them into minerals, which return to the soil and are then used by producers. For example: bacteria and mushrooms.
FOOD CHAINS
Food chains show how living things feed on other living things in an ecosystem. Food chains always start with a producer. The next living thing in food chains are consumers. The arrows in a food chain always point from the food to the consumer.
FOOD WEBS
Food webs are made up of many food chains joined together and interconnected. Food webs give us a more complete picture of how living things feed on other living things in an ecosystem.
BENEFICIAL AND HARMFUL RELATIONSHIPS
- MUTUALISM: is the relationship between two species when both benefit. For example: bees obtain nectar from flowers and the flowers are pollinated by the bees.
- COMMENSALISM: is the relationship between two species when one benefits and the other remains unaffected. For example, remoras live around sharks and feed on the bits of food sharks leave behind. This relationship benefits remoras but doesn't affect sharks.
- PARASITISM: is the relationship between two species when one benefits and the other suffers. The species that benefits is called a parasite. For example, fleas live on the skin of dogs and suck their blood. The dogs get weak and their skin itches. In this relationship, fleas benefit while dogs suffer.
- COMPETITION: is the relationship between different species that have the same needs. For example, lions and leopards compete for food, because they eat the same things.
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