- Slides: 38
Interactions Within Ecosystems
• Niche – Describes the roles an organism has within its ecosystem – Includes • Diet • Predators • Habitat • Interactions with its environment • Interactions with other organisms
Describe the niche of a Willow tree Describe the niche of a ground squirrel
– Knowing an organism’s niche can help explain why and how it acts and interacts with other organisms • One of the most important niches is what an organism eats – Based on what they eat, organisms are assigned different roles
1. Producer – Produce (make) their own food • Photosynthesis – Raw materials = carbon dioxide + water » Plants absorb the sun’s energy – Products = sugar (glucose) + oxygen
– Examples? • Green plants • Algae • Phytoplankton
• Consumer – Organisms that consume (eat) other living things to obtain energy
– 3 types of consumers • Herbivore = Organism that eats producers • Carnivore = Organism that eats other consumers ? • Omnivore = Organism that eats both producers & other consumers
Food Chains • Diagram that shows what eats what • Shows how energy stored in food passes from organism to organism
• 2 rules for drawing: 1. Arrow points from what is being eaten to what is eating it • FROM prey TO predator
2. Always START with a producer
• Make a food chain from the organisms below: – Phytoplankton (producer) – Large fish – Shrimp – Polar Bear – Seal • What types of food do you eat? Do you eat only one type, or many types?
Food Webs • Many food chains that are interconnected • Has several producers • Shows the flow of energy and nutrients for an entire ecosystem • Practice…
• Food Web Game – Identity cards – How do you fit into your ecosystem? • What do you eat? • Does anything eat you? • What other organisms might be around you?
• Stand in a circle • Each person: – Hold onto one part of the string – Pass the ball to another person in the group who has a role in the ecosystem that depends on you – Explain how the member you passed to depends on you • Continue passing the string until all of the members are connected
• Scenario 1 – A disease has infected and killed all of the herbivores. • If you are a herbivore, drop your string. – Who else can not survive? Drop your string. – What happened to the web? • Scenario 2 – It has been a very cold spring, and all of the producers have died • If you are a producer, drop your string – Who else can no longer survive? Drop your string. – What happens to the web?
• Flow of Energy – Producers (P) can only get energy from the Sun (me) – Herbivores (H) can only get energy from the producers (P) – Carnivores (C) can only get energy from the herbivores (H) – Omnivores (O) can get energy from producers or herbivores (H)
P P P P P H H H C C C O
Pyramid of Numbers • Another way to show ‘what eats what’ • Represents the number of individuals at each level in the food chain – Producers form the bottom level – Herbivores form the second level – Carnivores form the top levels • How many organisms are needed at each level?
• For each of the following situations: – Draw the pyramid that is represented by the numbers – Would the ecosystem survive? Why or why not? – Situation 1: 5 producers, 12 herbivores & carnivores 19 – Situation 2: 15 producers, 12 herbivores & carnivores 19 – Situation 3: 20 producers, 12 herbivores & carnivores 5
– Number of organisms DECREASES as you climb up the pyramid • Greatest number at the bottom (producers) • Provides a stable base to build the rest of the ecosystem on
• At each step along a food chain, some energy is used by the organism as fuel to live, grow and reproduce – Remaining energy (only 10%) is passed to next level of chain
• Scavengers & Decomposers – 2 important roles • Break down dead materials so they don’t accumulate • Nutrient cycling –Release nutrients back into the soil so they are available for uptake by other organisms
– Scavengers • Feed on dead or decaying matter – Decomposers • Grow on decaying matter • Absorb some nutrients; return the rest to the environment
• Symbiosis – When 2 different species live closely together in a relationship that lasts over time
• Adaptations – To survive in a certain niche, organisms must be adapted to their environment – Adaptation • Inherited characteristic that helps an organism survive and reproduce in its environment
– 2 types: • General adaptations – Allows organism to eat many different types of food or live in different habitats • Specialist adaptations – Allows organism to only eat one / a few types of food or live in one / a few types of habitat
• • • Insects Worms Mice Seeds Fish Flower Pollen
Laboratory Activity 2: Tools for the Task