How do organisms interact and depend on one another in an ecosystem?

1. How do organisms interact and depend on one another in an ecosystem? A food chain shows how organisms get their food. The first organism in a food chain is a producer; consumers or decomposers follow Producer consumer decomposer

2. Most energy comes from the sun Plants, also called producers, convert energy from the sun into food through a process called photosynthesis.   Photosynthesis is a process which uses water, carbon dioxide, and sunlight energy to make sugars.  Plants do this in special cells called chloroplasts.  These are usually green because of a pigment called chlorophyll.  Most photosynthesis happens in a plant's leaves, which is why they are green. When an animal eats a plant, some of the energy gets passed from the plant to the animal.  A food web shows this passage of energy, by showing what animals can eat what, and who gets eaten by who

3. Consumers Animals, fungi, and some kinds of microorganisms do not make their own food. Living things that cannot make their own food are consumers. Consumers get energy by eating other living things. Herbivores – eat only plants Carnivores – eat only meat Omnivores – eat both plants and animals.

4. Decomposers Decomposers are bacteria, microorganisms, fungi or other animals (termites and worms) that feed on decaying matter. These decomposers speed up the decaying process that releases nutrients back into the food chain for absorption by plants. They are Earth’s natural recyclers. What would happen if a forest had no decomposers? Plants would use up all the nutrients in the soil, and the ground would be covered in animal wastes and dead organisms.

5. Predators and Prey Predators are animals that eat other animals. The animals they hunt and eat are called the prey. Predators often have eyes that are in front of the head. This placement helps the animals judge how far away their prey is. The eyes of prey are often on the side of its head. This placement allows the prey to avoid predators by seeing a wide area.

6. Parasites and Hosts A parasite is an organism that feeds off another organism, called a host. Fleas, leeches, and ticks are parasites. Ticks bite their hosts. Then they take blood from their host for food. Unlike a predator, a parasite does not usually kill the animal it feeds on. If the host dies, the parasite loses its source of food.

7. Food Chains and Food Webs A food chain shows a single path that energy and nutrients take through an ecosystem. Arrows in a food chain show how energy and nutrients move. sun plants hare owl bacteria A food web is a system of overlapping food chains. In a food web, energy and nutrients can flow through many branches and gives a better picture of the complex way that energy and nutrients move in an ecosystem.

8. Food Web

9. What affects populations? The number of living things that can live in any ecosystem is limited. A limiting factor is an environmental factor that determines how large a population can be. The most common limiting factors are: Water Food Space shelter

10. Some factors that influence populations • Shelter Availability • Climate change • Human intrusion • Natural events • Amount of Space • Overcrowding • Change in Population Size • Water Availability • Pollution • Climate/Weather • Competition for Food • Predators • Parasites • Disease

11. Population Increase If there are more plants than usual in an area, populations of animals that eat that plant may increase. If one animal’s population increases, the population of animals that eat that animal might also increase. Increases in population are not always good. Sometimes a population will grow too large for the environment to support.

12. Population Decrease Other changes in limiting factors will cause a population to decrease. If the water supply in an area decreases, the population that needs water may decrease. Then the population of animals that eat that animal could decrease too.