Sherwin's Webquest-Food Chain

Introduction

A food chain is a linear network of links in a food web starting from producer organisms (such as grass or trees which use radiation from the sun to make their food) and ending at apex predator species (like grizzly bears or killer whales), detrivores (like earthworms or woodlice), or decomposerspecies (such as fungi or bacteria). A food chain also shows how the organisms are related with each other by the food they eat. Each level of a food chain represents a different trophic level. A food chain differs from a food web, because the complex network of different animals' feeding relations are aggregated and the chain only follows a direct, linear pathway of one animal at a time. A common metric used to quantify food web trophic structure is food chain length. In its simplest form, the length of a chain is the number of links between a trophic consumer and the base of the web and the mean chain length of an entire web is the arithmetic average of the lengths of all chains in a food web.[1][2]

Food chains were first introduced by the African-Arab scientist and philosopher Al-Jahiz in the 9th century and later popularized in a book published in 1927 by Charles Elton, which also introduced the food web concept.[3][4][5]

Food chain length[edit]

This food web of waterbirds fromChesapeake Bay is a network of food chains

Food chains are directional paths of trophic energy or, equivalently, sequences of links that start with basal species, such as producers or fine organic matter, and end with consumer organisms. [6]:370

The food chain's length is a continuous variable that provides a measure of the passage of energy and an index of ecological structure that increases in value counting progressively through the linkages in a linear fashion from the lowest to the highest trophic (feeding) levels.[7] Food chains are often used in ecological modeling (such as a three species food chain). They are simplified abstractions of real food webs, but complex in their dynamics and mathematical implications.[8] Ecologists have formulated and tested hypotheses regarding the nature of ecological patterns associated with food chain length, such as increasing length increasing with ecosystem size, reduction of energy at each successive level, or the proposition that long food chain lengths are unstable.[7] Food chain studies have an important role inecotoxicology studies tracing the pathways and biomagnification of environmental contaminants.[9]

Food chains vary in length from three to six or more levels. A food chain consisting of a flower, a frog, a snake and an owl consists of four levels; whereas a food chain consisting of grass, a grasshopper, a rat, a snake and finally a hawk consists of five levels. Producers, such as plants, are organisms that utilize solar or chemical energy to synthesize starch. All food chains must start with a producer. In the deep sea, food chains centered around hydrothermal vents and cold seeps exist in the absence of sunlight. Chemosynthetic bacteria and archaea use hydrogen sulfide and methane from hydrothermal vents and cold seeps as an energy source (just as plants use sunlight) to produce carbohydrates; they form the base of the food chain.Consumers are organisms that eat other organisms. All organisms in a food chain, except the first organism, are consumers.

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Food Chains and Food Webs
"What's for dinner?"

Animal Pages
Biomes
Food Theme Page

Food web Every organism needs to obtain energy in order to live. For example, plants get energy from the sun, some animals eat plants, and some animals eat other animals.

A food chain is the sequence of who eats whom in a biological community (an ecosystem) to obtain nutrition. A food chain starts with the primary energy source, usually the sun or boiling-hot deep sea vents. The next link in the chain is an organism that make its own food from the primary energy source -- an example is photosynthetic plants that make their own food from sunlight (using a process called photosynthesis) and chemosynthetic bacteria that make their food energy from chemicals in hydrothermal vents. These are called autotrophs or primary producers.

Next come organisms that eat the autotrophs; these organisms are called herbivores or primary consumers -- an example is a rabbit that eats grass.

The next link in the chain is animals that eat herbivores - these are called secondary consumers -- an example is a snake that eat rabbits.

In turn, these animals are eaten by larger predators -- an example is an owl that eats snakes.

The tertiary consumers are are eaten by quaternary consumers -- an example is a hawk that eats owls. Each food chain end with a top predator, and animal with no natural enemies (like an alligator, hawk, or polar bear).

The arrows in a food chain show the flow of energy, from the sun or hydrothermal vent to a top predator. As the energy flows from organism to organism, energy is lost at each step. A network of many food chains is called a food web.

Trophic Levels:
The trophic level of an organism is the position it holds in a food chain.

Primary producers (organisms that make their own food from sunlight and/or chemical energy from deep sea vents) are the base of every food chain - these organisms are calledautotrophs.
Primary consumers are animals that eat primary producers; they are also called herbivores (plant-eaters).
Secondary consumers eat primary consumers. They are carnivores (meat-eaters) and omnivores (animals that eat both animals and plants).
Tertiary consumers eat secondary consumers.
Quaternary consumers eat tertiary consumers.
Food chains "end" with top predators, animals that have little or no natural enemies.

When any organism dies, it is eventually eaten by detrivores (like vultures, worms and crabs) and broken down by decomposers (mostly bacteria and fungi), and the exchange of energy continues.

Some organisms' position in the food chain can vary as their diet differs. For example, when a bear eats berries, the bear is functioning as a primary consumer. When a bear eats a plant-eating rodent, the bear is functioning as a secondary consumer. When the bear eats salmon, the bear is functioning as a tertiary consumer (this is because salmon is a secondary consumer, since salmon eat herring that eat zooplankton that eat phytoplankton, that make their own energy from sunlight). Think about how people's place in the food chain varies - often within a single meal.

Food web Numbers of Organisms:
In any food web, energy is lost each time one organism eats another. Because of this, there have to be many more plants than there are plant-eaters. There are more autotrophs than heterotrophs, and more plant-eaters than meat-eaters. Although there is intense competition between animals, there is also an interdependence. When one species goes extinct, it can affect an entire chain of other species and have unpredictable consequences.

Equilibrium
As the number of carnivores in a community increases, they eat more and more of the herbivores, decreasing the herbivore population. It then becomes harder and harder for the carnivores to find herbivores to eat, and the population of carnivores decreases. In this way, the carnivores and herbivores stay in a relatively stable equilibrium, each limiting the other's population. A similar equilibrium exists between plants and plant-eaters.

Food Chain Worksheets:

Picture Prompt of Fish Eating Fish Write a story about the picture of four fish (of decreasing size), chasing each other.	Picture Prompt of a Lion Chasing Zebras Write a story about a picture of three zebras running away from a lion.	Complete the Food Chains Worksheet #1 Circle the organisms that complete the food chains. Or go to the answers.	Complete the Food Chains Worksheet #2 Circle the organisms that complete the food chains. Or go to the answers.
Food Chain Fill in the Arrows Quiz #1 Fill in arrows that trace the flow of energy in four food chains, incuding ones from the ocean, city, prairie, and pond. Or go to the answers.	Food Chain Fill in the Arrows Quiz #2 Fill in arrows that trace the flow of energy in four food chains, incuding ones from the tundra, desert, rainforest, and swamp. Orgo to the answers.	Food Chain Information Plus Questions Worksheet Read the information about food chains then answer the questions about food chains. Or go to the answers.	Food Web Information Plus Questions Worksheet Read the information about food webs then answer the questions about food webs. Or go to the answers.
Food Chain Multiple Choice Comprehension Quiz #1 Answer ten multiple-choice questions about food chains. Or go to the answers.	Food Chain Multiple Choice Comprehension Quiz #2 Answer ten multiple-choice questions about food chains. Or go to the answers.	Food Chain Match Each Word to Its Definition Match each food web word to its definition (printable worksheet). Words: autotroph, heterotroph, carnivore, herbivore, primary consumer, secondary consumer, tertiary consumer. Or go to the answers.	Food Chain Spelling Word Questions Use the list of food chain spelling words to answer simple questions. Words: diet, prey, ecosystem, organism, herbivore, carnivore, omnivore, detrivore, decomposer, nutrients, producer, consumer. Or go to the answers.
Food Chain Cloze Worksheet Fill in the blanks in the passage about food chains. Word bank: arrows, energy, sea, sun, herbivores, consumers, photosynthesis, bears, detrivores, top, grass, carnivores, lost, omnivores, meal, snakes. Or go to the answers.	Food Chain Trophic Levels Worksheet Write organisms for each trophic level. Sample answers: Primary consumers: cows, rabbits, tadpoles, ants, zooplankton, mice. Secondary consumers: frogs, small fish, krill, spiders. Tertiary consumers: snakes, raccoons, foxes, fish. Quaternary consumers: wolves, sharks, coyotes, hawks, bobcats. Note: Many animals can occupy different trophic levels as their diet varies.

Dictionary Definition Quizzes

Autotroph Definition - Multiple Choice Comprehension Quiz Answer 8 multiple-choice questions on the definition of autotroph; a lesson in using a dictionary. Go to the answers.	Carnivorous Definition - Multiple Choice Comprehension Quiz Answer 8 multiple-choice questions on the definition of carnivorous; a lesson in using a dictionary. Go to the answers.	Heterotroph Definition - Multiple Choice Comprehension Quiz Answer 8 multiple-choice questions on the definition of heterotroph; a lesson in using a dictionary. Go to the answers.
Omnivore Definition - Multiple Choice Comprehension Quiz Answer 8 multiple-choice questions on the definition of omnivore; a lesson in using a dictionary. Go to the answers.	Write Food Web-Related Definitions In this worksheet, write the definition of a word, what part of speech it is, and use it in a sentence. Words: herbivore, carnivore, omnivore, detrivore, autotroph, heterotroph, predator, prey, top predator, consume. Or go to the answers. Or go to a pdf of the questions and answers (subscribers only).	Food Web / Food Chain Vocabulary Word List A list of words related to food webs and food

Task

https://www.pinterest.com/explore/food-chain-activities/

Name: ____________________________________ Food Chain Questions 1. Draw a food chain that shows how a mouse, an owl, and grass are connected. 2. Explain how plants get their food. ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ 3. Can an animal be a both predator and prey? Explain and give an example. ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ 4. Name two animals that are omnivores. Give an example of a plant and an animal that each one might eat. ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ Super Teacher Worksheets - www.superteacherworksheets.com 5. There are fewer animals in a desert than a rainforest. Why? ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ 6. Dinosaurs like the Tyrannosaurus rex have been extinct for millions of years. Even though they have never seen a living Tyrannosaurus, scientists who have studied dinosaur fossils are certain that the Tyrannosaurus rex was a carnivore. Explain how they could they know this. ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ 7. How is a food chain different from a food web? ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ 8. Give an example of when two different species might compete for the same prey. ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________ Super Teacher Worksheets - www.superteacherworksheets.com 