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Food Chains & Food Webs As you study more about ecosystems and cycles in life, you will see the terms food chains and food webs. In every food chain or food web you will find producers, consumers and decomposers. A food chain is a single linear path that illustrates the flow of energy through an ecosystem. A food web is a branched model that illustrates and includes several food chains. Many animals eat a variety of different foods to get enough energy to live. Food energy does not always move in a straight line like a chain. Often the energy moves in various ways so that a drawing of it looks more like a web than a chain, that is why it is better to call it a food web. https://www.youtube.com/watch?v=CDO_B1Bbjl8 Food Chains Mr. DeMaio 6:35 min
Food Chains & Food WebsExtra Videos. https://www.youtube.com/watch?v=MuKs9o1s8h8 Fabulous Food Chains: Crash Course Kids #7.1 3:24 min
What is the difference between a food chain and a food web? A food web is a “more complete” model of the feeding relationships and flow of energy in an ecosystem. In every food chain or food web you will find producers, consumers and decomposers. The arrows point in the direction the energy is flowing. The arrows DO NOT point to who is doing the eating.
https://www.youtube.com/watch?v=kqUFvd0J1dsEnergy Flow through an ecosystem7:26 min
The Producers • Producersare the beginning of a simple food chain. Producers are plants. Plants are at the beginning of every food chain that involves the Sun. All energy comes from the Sun and plants are the ones who make food with that energy. They use the process of photosynthesis. Grass is a producer that makes its own food.
Main idea???? • Plants are producers and they are beginning of every food chain.
The Consumers • Consumers are the next link in a food chain. The levels start with the organisms that eat plants. Scientists named this first group of organisms the primary consumers. They are also called herbivores (sometimes omnivores) They are the plant eaters of the chain. A grasshopper is a primary consumer.
Main idea???? • Primary consumers are the “first” consumers. They are usually herbivores (or sometimes omnivores).
Secondary consumers eat the primary consumers. A mouse that eats the grasshopper is a secondary consumers, also called a carnivore (or omnivore).
Main idea???? • Secondary consumers are the second consumers in a food chain.
In some ecosystems, there is a third level of consumer called the tertiary consumer (that means third level). These are consumers that eat the secondary consumers and are carnivores (or omnivores). A tertiary consumer in this example would be a snake that eats the mouse that ate the grasshopper.
Main idea??? • Tertiary consumers are the 3rd consumers in a food chain.
Some ecosystem even have a quaternary consumers (that means fourth level). Quaternary consumers eat the tertiary consumers and are carnivores (or omnivores). A quaternary consumer in this example would be hawk that eats the snake, that eats the mouse, that eats the grasshopper. The hawk is the apex predator in this food chain. An apex predator, also known as an alpha predator, super predator, top predator. It is a predator at the top of a food chain on which no other creatures predate.
Main idea??? • Some food chains/webs have quaternary (4th level) consumers, and they are usually apex (top predators).
The Decomposers • Thelast links in the chain are the decomposers. When an organism dies, they eat it. If you poop, they eat that. If you lose a leaf, they eat it. Whenever something that was alive dies, the decomposers get it. Decomposers break down nutrients in the dead "stuff" and return it to the soil. The producers can then use the nutrients once it's in the soil. The decomposers complete the system, returning important nutrients to the producers.
Main idea??? • Decomposers are always the last step in any food chain, they break down waste and return the nutrients to the soil for the producers to use.
https://www.youtube.com/watch?v=-oVavgmveyY • Amoeba Sisters 5:48 Food Webs and Energy Pyramids
Energy Pyramids • Knowing the links of a food chain helps you see direction energy moves through an ecosystem. An energy pyramid shows how much energyis available in each level in the ecosystem. • An ecosystem must have many producers to support a pyramid of consumers. There is not enough energy in most ecosystems to support a larger number of carnivores.
Each time an animal eats, only a small amount of energyis passed to the next level consumer. Producers use most of the energy they make, passing on only about 10% to the consumers that eat them. The consumers, also only pass on about 10% percent of their energy to the next level consumer.
For example, grasshoppers eat 10stems of grass. A mouse might eat ten grasshoppers. If the mouse wanted to only eat one grasshopper, the grasshoppers would need to eat one hundred stems of grass to pass on enough energy to the mouse.
https://www.youtube.com/watch?v=qUZkWZ12A8s Learn Biology: Trophic Levels and Producer vs. Consumer 2:21 min ApexAnimals at the top of the food chain. predators: Ex: Hawk. Tertiary Or“third”Consumers. ConsumersEx: Snakeeats the mouse,that ate the grasshopper that ate the grass. SecondaryOr “second”Consumers. Consumers: Ex: Mouse, eats grasshopper, that ate the grass. Primary Or “first”Consumers. Consumers: Ex:Grasshopper eats grass. Producers: Plants. Ex: Grass Energy Pyramids
https://www.youtube.com/watch?v=IuRgUF-pJZMEnergy Transfers in an Ecosystem15:21… Review of food chain, food web, energy pyramid!
https://www.youtube.com/watch?v=mCHdhXMFhcU The Virtual School 2:52 min Bellwork List the trophic levels from the bottom up… According to the VIDEO there are 5!!!
2. What is the difference between food webs/chains and Energy Pyramids???3. How much energy is transferred to the next tropic level? Food webs and chains show the direction the energy is traveling… and Energy pyramids show HOW MUCH energy is available in that ecosystem. 10%
Carrying CapacityThe number of organisms a given area can support over time is called carrying capacity. https://www.youtube.com/watch?v=QI2ixJeIxEU Carrying capacity 4:34
How Deep is the Barrel? The barrel represents the marsh habitat - the amount of food, water, and cover for a fixed number of muskrats.
The water in the barrel is the number of muskrats the habitat can support. The pipe pouring water into the barrel represents the new muskrats that are born in the marsh. The water spilling out is the number of muskrats that die each year due to starvation, predators, disease, or other factors.
The barrel can only hold so much water. That is, there is a limit to the number of muskrats that can survive here from year to year unless the habitat (the size of the barrel) is changed in some way.
Carrying Capacity Graph What is the approximate carrying capacity of the Reindeer? 100
Carrying Capacity & Overshoot Overshoot occurs when a population exceeds the carrying capacity of the environment. This occurs when resources are plenty.
Carrying Capacity & Crash or Die Off The result of overshoot is called crash or die off. This occurs when resources become limited, because the population is too big.
Bellwork 10-28 (Wednesday) • What does carrying capacity mean? 2. What happens to a population after it overshoots it’s carrying capacity?
2. After a populations overshoots its carrying capacity, the populations will then crash or die off (drop). 1. The number of muskrats that could live in the marsh.
Limiting Factors: are things that prevent a population from growing any larger. • Competition • (food, shelter, mates, water) • Disease • Predation (hunters) • Natural Disaster • Weather https://www.youtube.com/watch?v=CuwrZUTeEqM&index=3&list=PL1584FDFF24D0F6A2 Limiting Factors TV Broadcast 2:17 min https://www.youtube.com/watch?v=8FPMP41LYJ8 Harry and Jerry 1:43 min Activity http://www.mtsu.edu/glade-center/teaching/21_Limiting%20Factors%20in%20the%20Glades.pdf
When resource are limited…. Individuals often compete… many will die. • Competition • Lack of shelter • Lack of mates • Lack of food • Lack of water
Limiting Factors • Limiting factors are things that prevent a population from growing to big. • For example, 50 rabbits may live in a habitat that has enough water, shelterand space to support 100 rabbits… • but if there is only enough food for 50 rabbits, the population will not grow any larger. • In this example, food is the limiting factor.
Food is not the only factor that may limit population growth. • For example, there may be enough food to support a 100 rabbits, but only nesting sites for 50.
Or maybe there is plenty of food, water, and space to support a 100 rabbits in an area, but predators are the limiting factor.
Important….. To remember…Limiting factors determine an ecosystems carrying capacity.
During the winter months,it can be difficult for deer, moose and the wolves to survive, especially with the harsh, cold weather and the scarcity of food during this time.
Shortage of Water: Called drought At times, water sources severely dry up, which in turn, affects their carrying capacity. The deer and moose population depend on these water sources. If the need for water exceeds the carrying capacity during that time, then many Of them will die of thirst.
