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Food Web Food Web

All organisms, dead or alive, are potential food sources for other organisms. A caterpillar eats a leaf, a robin eats the caterpillar, a hawk eats the robin. Eventually, the tree and the hawk also die and are consumed by decomposers. Organisms in an ecological community are related to each other through their dependence on other organisms for food. In a food chain a producer is eaten by a herbivore that is in turn eaten by a carnivore. Eventually, the carnivore dies and is eaten by a decomposer. For example, in a lake, phytoplankton are eaten by zooplankton and zooplankton are eaten by small fish. The small fish are eaten by large fish. The large fish eventually die and decompose. Nothing goes to waste. Food chains are channels for the oneway flow of solar energy captured by photosynthesis through the living components of ecosystems. Food chains are also pathways for the recycling of nutrients from producers, through herbivores, carnivores, omnivores, and decomposers, finally returning to the producers. The perfectly linear relations represented by food chains are almost never found in natural ecosystems. Although all organisms have somewhat specialized diets, most can eat a variety of different foods. Thus, each trophic level appears as part of several different interconnected food chains. These food chains combine into highly complex food webs. As with food chains, a food web's source of energy is the sun. The solar energy is harvested by producers such as green plants or algae. These producers are known as autotrophs or photosynthesizing autotrophs. Almost all other organisms obtain their energy, directly or indirectly, from the sun. The exceptions are the communities found around deep ocean thermal vents, which are supported by various bacteria that convert heat energy into stored chemical energy. These bacteria are known as chemotrophs or chemosynthetic autotrophs. Autotrophs are always found at the first trophic level. In an ecosystem this trophic level may include monerans, protists, and several different phyla of plants. They can all be placed at the first trophic level because they all have the same source of energy, and the entire food web depends on the energy harvested by them. For example, in a grazing food web, a herbivore eats living plant tissue and is eaten in turn by an array of carnivores and omnivores. Herbivores and the carnivores that prey on them are known as heterotrophs. In contrast, a detrivore (also a heterotroph) harvests energy from dead organic material and provides energy for a separate food chain. Each step in a food web or food chain involves a transfer of matter and energy (in the form of chemical bonds stored in food) from organism to organism. Thus food webs are energy webs because the relationships represented by connections in the web represent the flow of energy from a group of organisms at one trophic level to another group of organisms at a different level. Because energy is lost (as waste heat) at each step, food chains rarely involve more than four or five steps or trophic levels. At each level the organisms waste much energy in the form of heat generated by normal activity. Only a fraction is stored as food or used for growth. Only about 10 percent of the food entering a link is available for the next organism in the chain. After about five links, there is insufficient energy to support a population of organisms (other than decomposers). For example, in the food chain starting with diatoms and ending with killer whales, only about 0.01 percent of the initial energy stored by the diatoms is delivered to the killer whales. Energy flow through a food web depends greatly on the nature of the producers at the first trophic level. These are usually photosynthetic plants, phytoplankton, or algae. In forest ecosystems, trees are the largest and most abundant organism. They determine the physical structure of the ecosystem, and they can be eaten directly by small or even very large animals. However, much of the matter and energy harvested by the trees goes to build a supporting structure. These supporting structures are composed of cellulose and other wood fibers that are poor sources of energy (although they may be good sources of valuable minerals and other nutrients). In contrast, grasses do not invest much energy in supporting structures, so more energy is available per kilogram of plant material present to the grazers that obtain energy from plants. Consequently, all of the aboveground parts of the grass plants are eaten by herbivores. Energy spreads out through the food web, from the lowest trophic level to the highest. At the "top of the food chain," large carnivores harvest the remaining energy. However, all things eventually die, no matter where they are in the food web, and the dead organic matter accumulates in the soil, lake bottom, or forest floor. This detritus becomes the basis for a completely different ecosystem, the detritus food web. Detritus feeders and decomposers harvest solar energy from the detritus by breaking down the organic material into simpler organic compounds and inorganic compounds. By this process, the matter is recycled and made available for reuse by plants. The detritus food web is vitally important to all ecosystems on Earth. Without it, dead organic matter would accumulate and bury everything. Humans are omnivores. They can operate on several trophic levels, eating plants, insects, mammals, birds, fish, mollusks, and many other organisms. Humans can also shorten the food chain when resources are scarce. In areas of the world where the population may be straining resources, people commonly increase the total food supply by eliminating one or more steps in the food chain. For example, to obtain more energy humans can switch from eating herbivores that obtain their energy from cereal grains to eating the cereal grains themselves. The food web does not tell us everything there is to know about the complex biological communities called ecosystems. Not all relationships are equally important in these dynamic, evolving communities. Food webs contain both strong and weak links. Weak links can often be broken with little impact on the community. On the other hand, some species have a disproportionately large effect on the community in which they occur. Called key-stone species, they help to maintain diversity by controlling populations of species that would otherwise come to dominate the community. Or they may provide critical resources for a wide range of species. For example, in the intertidal communities of the Northwest Pacific coast of North America, the starfish Pisaster ochraceus feeds on the small mussel Mytilus californius. Experiments have shown that when the starfish is artificially removed, the population of mussels explodes, soon covering all available space. Other species are crowded out. The interaction between Pisaster and Mytilus helps to maintain the species diversity of these intertidal communities. Research has shown that ecological communities with complex feeding relationships have greater long-term stability and are less affected by external stresses. This suggests an evolutionary basis for the diverse and complex ecological relationships found in many communities of organisms. However, humans often violate this sound ecological principle in order to increase agricultural productivity by creating artificial ecosystems that contain only one plant, such as corn. These systems are called monocultures. While greater agricultural productivity is possible with monoculture crops, they are very unstable ecosystems. Disease, drought, or a new insect pest can easily destroy an entire year's harvest. see also Biomass; Feeding; Feeding Strategies; Trophic Level. Elliot Richmond Curtis, Helena, and N. Sue Barnes. Biology, 5th ed. New York: Worth, 1989. Miller G. Tyler, Jr. Living in the Environment, 6th ed. Belmont, CA: Wadsworth, 1990. Purves, William K., and Gordon H. Orians. Life: The Science of Biology. Sunderland, MA: Sinauer Associates, 1987.


From Yahoo Answers

Question:Describe the differences between a food chain and a food web. Please include details.

Answers:food chain Food chains describe the eating relationships between species within an ecosystem or a particular living place. Many types of food chains or webs are applicable depending on habitat or environmental factors. Every known food chain begins with a type of autotroph, whether it be a plant or some kind of unicellular organism. food web A food web is similar to a food chain; only bigger. Food webs show how plants and animals are connected in many ways to help them all survive, unlike food chains that just follow one path. For example, a tree produces acorns - this is called the producer. Mice and other insects eat these acorns and because there are many mice, the weasels, snakes and racoons have food. With insects in the acorns, other predators would be attracted (like skunks or opposums) and therefore, foxes, hawks or owls could all find food.

Question:1 Which refers to decomposers? A They make their own food. B They absorb nutrients from dead animals. C They eat dead animals. D They live inside the body of living organisms. 2 Which is a scavenger? A Eagle B Hawk C Falcon D Vulture 3 Give a process that results in loss of energy at each trophic level. 4 A diagram that shows the amount of energy at each trophic level is an _____________ ? 5 A diagram that shows feeding relationships in an ecosystem is a _____________ ? 20 minutes ago

Answers:1. it is B. Decomposers are bacteria and stuff that absorb the nutrients from dead animals. 2. Vulture. 3. idk, I think it's decomposing >_< 4. Its a Food Chain 5. Its a Food Web.

Question:for my assignment. Please let it be thorough and make sure it has nearly every animal in the sahara desert. (;

Answers:Well!!!! Sahara Desert is the largest hot desert in the world. It is in North Africa spreading the entire north western region across 9 countries. It is one of the harshest ecosystems on this earth ! The daytime temperature can rise to over 45 degrees Celsius or 113 degrees F. The nights are extremely cold. Strong hot winds blow across the desert carrying sand from one place to another. The dust storms are very common in the hot deserts. They get hardly 10 inches of rain . A typical Sahara desert food chain consists of the date palm (producer) which produces the date fruits. These date fruits when the fall down are eaten by the kangaroo rats ( herbivore ). As the kangroo rat is running away to safety it is caught and eaten by the sandy cat a (carnivore). The sandy cat digests the rat and leaves its droppings in the sand. Soon the decomposers in the sand, the insects, bacteria and worms decompose the droppings and return the nutrients back to the soil for the date palms to absorb and grow. All these animals and plants of the deserts are very well adapted to live successfully in the extreme climatic conditions. Here are few picture:

Question:So, I've done my research and I have these species but I don't know how they link; and can't find it on any sites. So I was wondering if someone could explain or somehow turn these species into a food web/chain... Carnivores: Leopards Jungle Cat Hyenas Jackals Mongoose Civet Cats Ratels Desert Cats Rusty-spotted cats Herbivores: Chital Nilgai Smabar Four-horned Antelope Chinkara Wild Bear Blackbucks Produces: ??? (I can't find that information) THIS IS BASED ON THE ECOSYSTEM OF THE GIR FOREST INHABITING THE ASIATIC LION Thanks Produces = grass, shrub etc. And if anyone knows what decomposes are in this food web thatd help heaps

Answers:Just put the herbivores at the bottom and the carnivores at the top then put some arrows to form a food web. I think on ur question is "producers" rather than produces. So put that at the lowest and draw arrows pointing to the top.

From Youtube

The food chain :The grassland ecosystem and the food chain.

Ocean Food Webs - Ecosystems Defined :In this segment, we explore various definitions of an ecosystem, as they help us better understand the time- and space-varying nature of the living and non-living components of ocean ecosystems.