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| If you know of any other great Science web sites that I should add to my site, email me and let me know! |
| Food Chains and Webs - What is a food chain and a food web? Find out why there are more herbivores than carnivores. www.vtaide.com/png/foodchains.htm |
| Food Webs - All living things in and around a pond or lake are inter-related. The food web shows how each require the other to provide the best habitat. www.broadwaters.fsnet.co.uk/food-web.htm |
| EcoKids - Build your own food chain! http://ecokids.earthday.ca/pub/eco_info/topics/frogs/chain_reaction/index.cfm |
| Ocean Link - Want to find out more about oceanic food webs? Well this is the site for you! http://oceanlink.island.net/oinfo/foodweb/foodweb.html |
| Planet Pals - What is a food chain? Let's find out . . . www.planetpals.com/foodchain.html |
| Science Bob - what is the difference between a food web and a food chain? www.sciencebob.com/lab/q-web-chain.html |
| CoralReef Network - Check out the food web on the coral reef!. www.coralreefnetwork.com/educate/shows/foodwebs/slide1.htm |
| Arcy Tech - This page contains a description of food chains and food webs in an ecosystem as well as a few examples.. www.arcytech.org/java/populations/fact_foodchain.htm |
| U N D E R S T A N D I N G F O O D C H A I N S A N D F O O D W E B S |
| FIRST THINGS FIRST Before we can start discussing food webs and food chains we have to have a cursory knowledge of the different types of organisms that make up such ecosystematic traces of energy. So here we go . . . In order to understand how food chains and food webs work you first must understand the feeding relationships between the organisms in that particular ecosystem. You see, all organisms need energy in order to survive, without it they would all . . . well . . . die! and that would be awful. Organisms can be split up into three primary groups based upon the ways in which they obtain their energy. You have producers, consumers and decomposers. First of all let's talk about producers; they are known for their amazing ability to make their own food. Producers use the energy from the Sun combined with other naturally occurring resources to make sugars (called glucose) they use for food. Organisms included in this category are trees, flowers, plants, moss, algae, plankton, etc. Plants make up the bulk of the worlds producers. Now let's tackle the world of consumers. Consumers are organisms that must get their energy by eating some other organism. Within the wild world of ccnsumers are a few smaller categories. You see, all consumers are broken down and separated into different groups based upon what they eat. Consumers that get their fill of energy need by eating plant materials are referred to as herbivores, or plant-eaters. They feed directly on producers and eat nothing else. The friendly neighborhood bunny and the deer that comes and nibbles on your shrubs in the middle of the night are prime examples. You know those squirrels that you often see in the middle of the road, yeah they are herbivores also, they love those acorns! Then there are the infamous carnivores. Growl! Growl! These guys are your meat-eaters. You don't want to encounter one of these fellas in the middle of the night out in the wild while you're out on a nice moonlit stroll with your sweetheart! They get their energy by eating other animals, yeah sorry, carrots won't satisfy these wild beasts. You might be familiar with the like of some of the more popular carnivores; lions, tigers, sharks, wolves and eagles. They are amazing to watch in action, such power and ferocity are to be admired, but from a distance . . . you wouldn't want to become their next meal. Within the realm of carnivores you have another bread known as scavengers. These guys don't take the time to hunt down their prey like the other predatory carnivores, instead they wait to feed on the carcasses of animals that have already been killed and left behind or died of natural causes. Probably the most famous scavenger is the vulture, others in his fold would be the hyena, and crabs. The third and final installement of the wild world of consumers belongs to the omnivore. The omnivore is special. They have the ability to eat both producers and other consumers. These guys are typically at the top of the food chain and include organisms such as bears and people. Some would say that people who claim to be vegetarians are not omnivores but rather herbivores because all they eat are plant materials. Even though some may choose to eat only vegetables they still have the ability to eat meat and can still digest that type of food; therefore, even though they would consider themselves herbivores, they are still technically omnivores, sorry to disappoint you. By the way . . . the great white shark on Shark Tales that claims to be a vegetarian - Lenny . . . yeah, not possible, nice thought and makes for an interesting story line, but altogether implausible . . . just thought I would share. Okay, so we have talked about producers and consumers; now for the last of the three primary groups of organisms decomposers. These guys are really cool! You see, they feed on the remains of dead organisms and they also feed on other organisms waste! Yeah, I know, totally cool! Right?! Organisms that fall into this category are going to be things like, bacteria, fungi, worms, and some insects. This is probably the smallest of the three primary groups of consumers, but the certainly play an important role in every ecosystem. Decomposers break down the remains of those dead organisms and animal waste and return vital nutrient back to the soil, that the producers need and so the cycle of life can continue on and on and on . . . yeah, I would say that is a pretty important job! Hmm . . . I wonder what would happen if we didn't have any decomposers? S C A R Y ! ! ! I'M NOT FINISHED YET! More to come so keep watching! |
| So we have already established that all organisms get their energy they need from somewhere, that somewhere being FOOD! Whether they make their own food (and no I am not talking about going to the grocery store buying a can of Raviolis and nuking it in the microwave), or they eat some other organisms that happens to look tasty at the moment, regardless all organisms must get their energy from somewhere. Organisms depend on each other for nourishment to survive and the graphic organizer that we use to track the linear progression of this energy is called a food chain. A food chain is a series of events (often unfortunate) in which one organism eats another, resulting in the flow of energy among the organisms involved. Food chains trace the path of energy as it moves from one organism to the next in an ecosystem. The Sun - you know that wonderful bright thing in the sky that will brun out your corneas if you stare at it directly for too long - is usually the thing that starts most food chains universally (I am sure that producers are extremely gratefull for that!) However, producers usually form the starting point for a food chain. We then use arrows to show the direction of the flow of energy (how the energy moves throughout the food chain). In the food chain above plant plankton are eaten by small animals called shrimp, which are eaten by fish, which are then eaten by bigger fish, until the bears that hang around the lake get hungry and go fishing. In this food chain the plankton is the producer, and as you can see the arrow shows that the plankton gets eaten by the shrimp and so the energy from the plankton them moves to the shrimp. The shrimp is what we call the primary consumer because it is the first consumer (a.k.a. the first one to grub down). When the fish eats the shrimp the energy that the shrimp has is then transferred to the fish, and as the second consumer we call this guy the . . . you guessed it, secondary consumer. Man you guys are smart! The bigger fish then eats the smaller fish and consumes its energy and is called the tertiary consumer. When the bear decides its time for a snack and snags himself one of those bigger fish out of the lake, since he is the fourth eater, we call him the quaternary consumer. The final link in this food chain comes into play once the bear dies and the bacteria or fungi breakdown the bears remains and pull off their role as decomposers. Just because decomposers are usually left out of food chains for some odd reason unbeknownst to myself, they are always the final link in any and every food chain, whether they are left out or not. |
| F O O D C H A I N S |
| Food chains are great at displaying the path that energy flows through an ecosystem in one linear path. But most organisms aren't eaten by just one consumer, but by several different possible consumers. They are usually a part of several food chains that overlap. People in the scientific community often use a food web to show as many possibilities of energy flow in an ecosystem as possible in order to complete their snapshot of the way organisms interact with one another. A food web is just a pattern of overlapping food chains in an ecosystem, like the one shown below. This food web displays that, just like most ecosystems, the energy in a lake ecosystem begins with the Sun. Without the Sun life on Earth would not exists anyway so it makes perfect sense that the Sun would be the beginning source of energy in an ecosystem, i digress. The energy from the Sun is then taken in by all the producers and through an amazing process called photosynthesis is converted into sugars called glucose. This energy that was taken in from the Sun, and transformed into glucose is then transferred throughout the ecosystem as the various level of consumers get hungry and chow down. And just as decomposers are usually left out of food chains, they are also usually left out of food webs too. But by now you might be getting the picture that decomposers are gravely important to the function and success of all the organisms in an ecosystem as they feed on the waste and remains of dead organisms. When they do this they break down these materials into a simpler form that is often returned to the environment and reused again by the producers . . . and thus the cycle of life continues, undisturbed, and everyone is happy . . . of course unless you are one of those primary, secondary, or tertiary consumers that are on the menu of a quaternary consumer, then I can't imagine that you would be too thrilled with the way things turn out. Sorry 'bout that! |
| F O O D W E B S |
| food chains & webs |