Animal food chain examples. The topic of the lesson is "food chains"
Who eats what
Compose power circuit telling about the heroes of the song "A grasshopper sat in the grass"
Animals that eat plant foods are called herbivores. Those animals that eat insects are called insectivores. Larger prey is hunted by predatory animals, or predators. Insects that eat other insects are also considered predators. Finally, there are omnivorous animals (they eat both plant and animal food).
Into what groups can animals be divided according to the way they feed? Complete the chart.
Food chains
Living things are interconnected in the food chain. For example: Aspens grow in the forest. Hares feed on their bark. A hare can be caught and eaten by a wolf. It turns out such a food chain: aspen - hare - wolf.
Make and write food chains.
a) spider, starling, fly
Answer: fly - spider - starling
b) stork, fly, frog
Answer: fly - frog - stork
c) mouse, grain, owl
Answer: grain - mouse - owl
d) slug, mushroom, frog
Answer: mushroom - slug - frog
e) hawk, chipmunk, bump
Answer: bump - chipmunk - hawk
Read short texts about animals from the book "With love to nature". Identify and write down the type of animal food.
In autumn, the badger begins to prepare for winter. He eats and gets very fat. Everything that comes across serves as food for him: beetles, slugs, lizards, frogs, mice, and sometimes even small hares. He eats both forest berries and fruits.
Answer: omnivorous badger
In winter, the fox catches mice under the snow, sometimes partridges. Sometimes she hunts hares. But hares run faster than a fox and can run away from it. In winter, foxes come close to human settlements and attack poultry.
Answer: carnivorous fox
In late summer and autumn, the squirrel collects mushrooms. She pricks them on tree branches to dry the mushrooms. And the squirrel stuffs nuts and acorns into hollows and crevices. All this will come in handy for her in the winter starvation.
Answer: herbivorous squirrel
The wolf is a dangerous animal. In summer, he attacks various animals. It also eats mice, frogs, lizards. It destroys bird nests on the ground, eats eggs, chicks, birds.
Answer: carnivorous wolf
The bear breaks open rotten stumps and looks for fat larvae of lumberjack beetles and other insects that feed on wood. He eats everything: he catches frogs, lizards, in a word, whatever he comes across. Digs bulbs and tubers of plants from the ground. You can often meet a bear in the berry fields, where he greedily eats berries. Sometimes a hungry bear attacks moose, deer.
Answer: omnivorous bear
According to the texts from the previous task, compose and write down several food chains.
1. strawberry - slug - badger
2. tree bark - hare - fox
3. grain - bird - wolf
4. wood - beetle larvae - lumberjack - bear
5. young shoots of trees - deer - bear
Make a food chain using the pictures.
Living organisms need energy and nutrients to survive. Autotrophs transform the radiant energy of the Sun in the process of photosynthesis, synthesizing organic substances from carbon dioxide and water.
Heterotrophs they use these organic substances in the process of nutrition, eventually decomposing them again to carbon dioxide and water, and the energy accumulated in them is spent on various life processes of organisms. Thus, the light energy of the Sun is converted into chemical energy organic matter, and then into mechanical and thermal.
All living organisms in the ecological system according to the type of nutrition can be divided into three functional groups - producers, consumers, decomposers.
1. Producers- These are green autotrophic plants that produce organic substances from inorganic and are able to accumulate solar energy.
2. Consumers- These are heterotrophic animals that consume ready-made organic substances. Consumers of the first order can use the organic substances of plants (herbivores). Heterotrophs that use animal food are divided into consumers of the II, III orders, etc. (carnivores). All of them use the energy of chemical bonds stored in organic substances by producers.
3. Reducers- These are heterotrophic microorganisms, fungi, destroying and mineralizing organic residues. Thus, decomposers, as it were, complete the cycle of substances, forming inorganic substances to enter a new cycle.
The sun provides a constant supply of energy, and living organisms eventually dissipate it in the form of heat. In the process of vital activity of organisms, there is a constant circulation of energy and substances, and each species uses only a part of the energy contained in organic substances. As a result, there are power circuits - food chains, food chains, representing a sequence of species that extract organic matter and energy from the original food substance, with each previous link becoming food for the next (Fig. 98).
Rice. 98. General scheme the food chain
In each link, most of the energy is spent in the form of heat, is lost, which limits the number of links in the chain. But most chains begin with a plant and end with a predator, and the largest one. Decomposers destroy organic matter at every level and are the final link in the food chain.
In connection with the decrease in energy at each level, there is a decrease in biomass. The trophic chain usually has no more than five levels and is an ecological pyramid, with a wide base at the bottom and tapering upwards (Fig. 99).
Rice. 99. Simplified diagram of the ecological pyramid of biomass (1) and the pyramid of numbers (2)
Ecological pyramid rule reflects the pattern according to which in any ecosystem the biomass of each next link is 10 times less than the previous one.
There are three types of ecological pyramids:
A pyramid showing the number of individuals at each level of the food chain - pyramid of numbers;
Pyramid of biomass of organic matter synthesized at each level - mass pyramid(biomass);
- energy pyramid, showing the amount of energy flow. Usually the food chain consists of 3-4 links:
plant → hare → wolf;
plant → vole → fox → eagle;
plant → caterpillar → tit → hawk;
plant → gopher → viper → eagle.
However, in real conditions in ecosystems, various food chains intersect with each other, forming branched networks. Almost all animals, with the exception of rare specialized types, use various sources food. Therefore, if one link in the chain falls out, there is no disturbance in the system. The greater the species diversity and the richer the food webs, the more stable the biocenosis.
In biocenoses, two types of food webs are distinguished: pasture and detrital.
1. IN pasture food web the flow of energy goes from plants to herbivorous animals, and then to consumers of a higher order. This eating network. Regardless of the size of the biocenosis and habitat, herbivorous animals (terrestrial, aquatic, soil) graze, eat green plants and transfer energy to the next levels (Fig. 100).
Rice. 100. Pasture food network in terrestrial biocenosis
2. If the flow of energy begins with dead plant and animal remains, excrement and goes to the primary detritivores - decomposers, partially decomposing organic matter, then such a food web is called detrital, or network of decay(Fig. 101). Primary detritophages include microorganisms (bacteria, fungi), small animals (worms, insect larvae).
Rice. 101. detrital food chain
Both types of the trophic chain are present in terrestrial biogeocenoses. In aquatic communities, the grazing chain predominates. In both cases, the energy is fully utilized.
Food chains form the basis of relationships in wildlife, but food relationships are not the only type of relationship between organisms. Some species can participate in the distribution, reproduction, dispersal of other species, create appropriate conditions for their existence. All the numerous and varied connections between living organisms and the environment ensure the existence of species in a stable, self-regulating ecosystem.
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§ 71. Ecological systems§ 73. Properties and structure of biocenoses
Question 28. Food chain. Types of food chains.
FOOD CHAIN(trophic chain, food chain), the relationship of organisms through the relationship of food - consumer (some serve as food for others). In this case, the transformation of matter and energy from producers(primary producers) through consumers(consumers) to decomposers(converters of dead organics into inorganic substances digestible by producers). There are 2 types of food chains - pasture and detrital. The pasture chain begins with green plants, goes to grazing herbivorous animals (consumers of the 1st order) and then to predators that prey on these animals (depending on the place in the chain - consumers of the 2nd and subsequent orders). The detrital chain starts with detritus (a product of organic decay), goes to microorganisms that feed on it, and then to detritus feeders (animals and microorganisms involved in the process of decomposition of dying organic matter).
An example of a pasture chain is its multi-channel model in the African savannah. Primary producers are herbage and trees, consumers of the 1st order are herbivorous insects and herbivores (ungulates, elephants, rhinos, etc.), 2nd order are predatory insects, 3rd order are carnivorous reptiles (snakes, etc.), 4th - predatory mammals and birds of prey. In turn, detritivores (scarab beetles, hyenas, jackals, vultures, etc.) at each stage of the pasture chain destroy the carcasses of dead animals and the remains of predators' food. The number of individuals included in the food chain consistently decreases in each of its links (the rule of the ecological pyramid), i.e., the number of victims each time significantly exceeds the number of their consumers. Food chains are not isolated from each other, but are intertwined with each other, forming food webs.
Question 29. What are ecological pyramids used for? Name them.
ecological pyramid- graphic images of the relationship between producers and consumers of all levels (herbivores, predators; species that feed on other predators) in the ecosystem.
The American zoologist Charles Elton proposed in 1927 to schematically depict these relationships.
In a schematic representation, each level is shown as a rectangle, the length or area of \u200b\u200bwhich corresponds to the numerical values \u200b\u200bof the food chain link (Elton's pyramid), their mass or energy. Rectangles arranged in a certain sequence create pyramids of various shapes.
The base of the pyramid is the first trophic level - the level of producers, the subsequent floors of the pyramid are formed by the next levels of the food chain - consumers of various orders. The height of all blocks in the pyramid is the same, and the length is proportional to the number, biomass or energy at the corresponding level.
Ecological pyramids are distinguished depending on the indicators on the basis of which the pyramid is built. At the same time, for all the pyramids, the basic rule is established, according to which in any ecosystem there are more plants than animals, herbivores than carnivores, insects than birds.
Based on the rule of the ecological pyramid, it is possible to determine or calculate the quantitative ratios of different plant and animal species in natural and artificially created ecological systems. For example, 1 kg of the mass of a sea animal (seal, dolphin) needs 10 kg of eaten fish, and these 10 kg already need 100 kg of their food - aquatic invertebrates, which, in turn, need to eat 1000 kg of algae and bacteria to form such a mass. In this case, the ecological pyramid will be stable.
However, as you know, there are exceptions to every rule, which will be considered in each type of ecological pyramids.
The first ecological schemes in the form of pyramids were built in the twenties of the XX century. Charles Elton. They were based on field observations of a number of animals of various size classes. Elton did not include primary producers in them and did not make any distinction between detritophages and decomposers. However, he noted that predators are usually larger than their prey, and realized that such a ratio is extremely specific only for certain size classes of animals. In the 1940s, the American ecologist Raymond Lindeman applied Elton's idea to trophic levels, abstracting away from the specific organisms that make them up. However, if it is easy to distribute animals into size classes, then determining which trophic level they belong to is much more difficult. In any case, this can only be done in a very simplified and generalized way. Nutritional ratios and the efficiency of energy transfer in the biotic component of an ecosystem are traditionally depicted as stepped pyramids. This provides a clear basis for comparing: 1) different ecosystems; 2) seasonal states of the same ecosystem; 3) different phases ecosystem changes. There are three types of pyramids: 1) pyramids of numbers based on counting organisms of each trophic level; 2) biomass pyramids, which use the total mass (usually dry) of organisms at each trophic level; 3) pyramids of energy, taking into account the energy intensity of organisms of each trophic level.
Types of ecological pyramids
pyramids of numbers- at each level, the number of individual organisms is postponed
The pyramid of numbers reflects a clear pattern discovered by Elton: the number of individuals that make up a sequential series of links from producers to consumers is steadily decreasing (Fig. 3).
For example, to feed one wolf, you need at least a few hares that he could hunt; to feed these hares, you need a fairly large number of various plants. In this case, the pyramid will look like a triangle with a wide base tapering upwards.
However, this form of a pyramid of numbers is not typical for all ecosystems. Sometimes they can be reversed, or inverted. This applies to forest food chains, when trees serve as producers, and insects as primary consumers. In this case, the level of primary consumers is numerically richer than the level of producers (a large number of insects feed on one tree), so the pyramids of numbers are the least informative and least indicative, i.e. the number of organisms of the same trophic level largely depends on their size.
biomass pyramids- characterizes the total dry or wet mass of organisms at a given trophic level, for example, in units of mass per unit area - g / m 2, kg / ha, t / km 2 or per volume - g / m 3 (Fig. 4)
Usually, in terrestrial biocenoses, the total mass of producers is greater than each subsequent link. In turn, the total mass of first-order consumers is greater than second-order consumers, and so on.
In this case (if the organisms do not differ too much in size), the pyramid will also look like a triangle with a wide base tapering upwards. However, there are significant exceptions to this rule. For example, in the seas, the biomass of herbivorous zooplankton is significantly (sometimes 2-3 times) greater than the biomass of phytoplankton, which is represented mainly by unicellular algae. This is explained by the fact that algae are very quickly eaten away by zooplankton, but the very high rate of division of their cells protects them from complete eating.
In general, terrestrial biogeocenoses, where producers are large and live relatively long, are characterized by relatively stable pyramids with a wide base. In aquatic ecosystems, where producers are small in size and have short life cycles, the biomass pyramid can be reversed or inverted (pointed downwards). So, in lakes and seas, the mass of plants exceeds the mass of consumers only during the flowering period (spring), and in the rest of the year the situation may be reversed.
Pyramids of numbers and biomass reflect the statics of the system, i.e., they characterize the number or biomass of organisms in a certain period of time. They do not provide complete information about the trophic structure of the ecosystem, although they allow solving a number of practical problems, especially those related to maintaining the stability of ecosystems.
The pyramid of numbers makes it possible, for example, to calculate the allowable value of catching fish or shooting animals during the hunting period without consequences for their normal reproduction.
energy pyramids- shows the magnitude of the energy flow or productivity at successive levels (Fig. 5).
In contrast to the pyramids of numbers and biomass, which reflect the statics of the system (the number of organisms at a given moment), the pyramid of energy, reflecting the picture of the speed of passage of a mass of food (amount of energy) through each trophic level of the food chain, gives the most complete picture of the functional organization of communities.
The shape of this pyramid is not affected by changes in the size and intensity of the metabolism of individuals, and if all sources of energy are taken into account, then the pyramid will always have a typical appearance with a wide base and a tapering top. When building a pyramid of energy, a rectangle is often added to its base, showing the influx of solar energy.
In 1942, the American ecologist R. Lindeman formulated the law of the pyramid of energies (the law of 10 percent), according to which, on average, about 10% of the energy received by the previous level of the ecological pyramid passes from one trophic level through food chains to another trophic level. The rest of the energy is lost in the form of thermal radiation, movement, etc. Organisms, as a result of metabolic processes, lose about 90% of all the energy that is expended to maintain their vital activity in each link of the food chain.
If a hare ate 10 kg of plant matter, then its own weight could increase by 1 kg. A fox or a wolf, eating 1 kg of hare, increases its mass by only 100 g. In woody plants, this proportion is much lower due to the fact that wood is poorly absorbed by organisms. For grasses and algae, this value is much higher, since they do not have hard-to-digest tissues. However, the general regularity of the process of energy transfer remains: much less energy passes through the upper trophic levels than through the lower ones.
The main condition for the existence of an ecosystem is the maintenance of the circulation of substances and the transformation of energy. It is provided thanks to trophic (food) relationships between species belonging to different functional groups. It is on the basis of these bonds that organic substances synthesized by producers from mineral substances with the absorption of solar energy are transferred to consumers and undergo chemical transformations. As a result of the vital activity of predominantly decomposers, the atoms of the main biogenic chemical elements pass from organic substances to inorganic (CO 2, NH 3, H 2 S, H 2 O). Then inorganic substances are used by producers to create new organic substances from them. And they are again involved in the cycle with the help of producers. If these substances were not used repeatedly, life on Earth would be impossible. After all, the reserves of substances absorbed by producers are not unlimited in nature. To implement a full-fledged cycle of substances in an ecosystem, all three functional groups of organisms must be available. And between them there must be constant interaction in the form of trophic links with the formation of trophic (food) chains, or food chains.
A food chain (food chain) is a sequence of organisms in which there is a gradual transfer of matter and energy from a source (previous link) to a consumer (next link).
In this case, one organism can eat another, eat its dead remains or waste products. Depending on the type of initial source of matter and energy, food chains are divided into two types: pasture (grazing chains) and detrital (decomposition chains).
Pasture chains (grazing chains)- food chains that start with producers and include consumers of different orders. IN general view pasture chain can be shown by the following diagram:
Producers -> Consumers of the 1st order -> Consumers of the 2nd order -> Consumers of the 3rd order
For example: 1) meadow food chain: meadow clover - butterfly - frog - snake; 2) the food chain of the reservoir: chlamydomonas - daphnia - gudgeon - pike perch. The arrows in the diagram show the direction of the transfer of matter and energy in the food chain.
Each organism in the food chain belongs to a specific trophic level.
Trophic level - a set of organisms that, depending on the way they eat and the type of food, make up a certain link in the food chain.
Trophic levels are usually numbered. The first trophic level is made up of autotrophic organisms - plants (producers), at the second trophic level there are herbivorous animals (consumers of the first order), at the third and subsequent levels - carnivores (consumers of the second, third, etc. orders).
In nature, almost all organisms feed on not one, but several types of food. Therefore, any organism can be at different trophic levels in the same food chain, depending on the nature of the food. For example, a hawk, eating mice, occupies the third trophic level, and eating snakes - the fourth. In addition, the same organism can be a link in different food chains, linking them together. So, a hawk can eat a lizard, a hare or a snake, which are part of different food chains.
In nature, pasture chains in their pure form are not found. They are interconnected by common food links and form food web, or power network. Its presence in the ecosystem contributes to the survival of organisms with a lack of a certain type of food due to the ability to use other food. And the wider the species diversity of individuals in the ecosystem, the more food chains in the food web and the more stable the ecosystem. The loss of one link from the food chain will not disrupt the entire ecosystem, as food sources from other food chains can be used.
Detritus chains (decomposition chains)- food chains that begin with detritus, include detritus feeders and decomposers, and end with minerals. In detrital chains, the substance and energy of detritus are transferred between detritophages and decomposers through the products of their vital activity.
For example: a dead bird - fly larvae - mold fungi - bacteria - minerals. If detritus does not require mechanical destruction, then it immediately turns into humus with subsequent mineralization.
Thanks to detrital chains, the cycle of substances is closed in nature. Dead organic substances in detrital chains are converted into minerals, which enter the environment, and from it are absorbed by plants (producers).
Pasture chains are predominantly located in the above-ground, and decomposition chains - in the underground tiers of ecosystems. The relationship between pasture chains and detrital chains is carried out through detritus that enters the soil. Detrital chains are connected with pasture chains through mineral substances extracted from the soil by producers. Due to the interconnection of pasture and detrital chains, a complex food web is formed in the ecosystem, which ensures the constancy of the processes of transformation of matter and energy.
Ecological pyramids
The process of transformation of matter and energy in pasture chains has certain regularities. At each trophic level of the pasture chain, not all of the eaten biomass is used to form the biomass of consumers of this level. A significant part of it is spent on the vital processes of organisms: movement, reproduction, maintaining body temperature, etc. In addition, part of the feed is not digested and enters the environment. In other words, most of the matter and the energy contained in it is lost when moving from one trophic level to another. The percentage of digestibility varies greatly and depends on the composition of the food and biological features organisms. Numerous studies have shown that at each trophic level of the food chain, on average, about 90% of energy is lost, and only 10% goes to the next level. The American ecologist R. Lindeman in 1942 formulated this pattern as 10% rule. Using this rule, you can calculate the amount of energy at any trophic level of the food chain, if its rate is known at one of them. With some degree of assumption, this rule is also used to determine the transition of biomass between trophic levels.
If at each trophic level of the food chain to determine the number of individuals, or their biomass, or the amount of energy contained in it, then it becomes obvious that these values decrease as we move towards the end of the food chain. This pattern was first established by the English ecologist C. Elton in 1927. He called it ecological pyramid rule and offered to express graphically. If any of the above characteristics of trophic levels are depicted as rectangles with the same scale and placed one above the other, then we get ecological pyramid.
Three types of ecological pyramids are known. Pyramid of numbers reflects the number of individuals in each link in the food chain. However, in the ecosystem, the second trophic level ( consumers of the 1st order) can be numerically richer than the first trophic level ( producers). In this case, an inverted pyramid of numbers is obtained. This is due to the participation in such pyramids of individuals that are not equivalent in size. An example is a pyramid of numbers, consisting of deciduous tree, leaf-eating insects, small insectivores and large birds of prey. biomass pyramid reflects the amount of organic matter accumulated at each trophic level of the food chain. The pyramid of biomass in terrestrial ecosystems is correct. And in the biomass pyramid for aquatic ecosystems, the biomass of the second trophic level, as a rule, is greater than the biomass of the first when it is determined at a particular moment. But since water producers (phytoplankton) have high speed formation of products, then in the end their biomass for the season will still be greater than the biomass of consumers of the first order. And this means that the rule of the ecological pyramid is also observed in aquatic ecosystems. energy pyramid reflects patterns of energy expenditure at different trophic levels.
Thus, the stock of matter and energy accumulated by plants in pasture food chains is quickly consumed (eaten away), so these chains cannot be long. They usually include three to five trophic levels.
In the ecosystem, producers, consumers and decomposers are connected by trophic relationships and form food chains: pasture and detrital. In pasture chains, the 10% rule and the ecological pyramid rule apply. Three types of ecological pyramids can be built: numbers, biomass and energy.
The energy of the sun plays a huge role in the reproduction of life. The amount of this energy is very high (about 55 kcal per 1 cm2 per year). Of this amount, producers - green plants - as a result of photosynthesis fix no more than 1-2% of energy, and deserts and the ocean - hundredths of a percent.
The number of links in the food chain may be different, but usually there are 3-4 (rarely 5). The fact is that so little energy is supplied to the final link of the food chain that it will not be enough if the number of organisms increases.
Rice. 1. Food chains in the terrestrial ecosystem
The set of organisms united by one type of food and occupying a certain position in the food chain is called trophic level. Organisms that receive their energy from the Sun through the same number of steps belong to the same trophic level.
The simplest food chain (or food chain) may consist of phytoplankton, followed by larger herbivorous planktonic crustaceans (zooplankton), and the chain ends with a whale (or small predators) that filter these crustaceans from the water.
Nature is complex. All its elements, living and non-living, are one whole, a complex of interacting and interconnected phenomena and beings adapted to each other. These are links in the same chain. And if at least one such link is removed from the general chain, the results may be unexpected.
Breaking food chains can have a particularly negative impact on forests, whether they are forest biocenoses of the temperate zone or biocenoses of the tropical forest that are rich in species diversity. Many species of trees, shrubs or herbaceous plants use the services of a particular pollinator - bees, wasps, butterflies or hummingbirds that live within the range of this plant species. As soon as the last flowering tree or herbaceous plant dies, the pollinator will be forced to leave this habitat. As a result, phytophages (herbivores) that feed on these plants or fruits of the tree will die. Predators that hunt phytophages will be left without food, and then changes will sequentially affect the rest of the food chain. As a result, they will also affect a person, since he has his own specific place in the food chain.
Food chains can be divided into two main types: grazing and detrital. Food prices that begin with autotrophic photosynthetic organisms are called pasture, or eating chains. At the top of the pasture chain are green plants. Phytophages are usually found at the second level of the pasture chain; animals that eat plants. An example of a pasture food chain is the relationship between organisms in a floodplain meadow. Such a chain begins with a meadow flowering plant. The next link is a butterfly that feeds on the nectar of a flower. Then comes the inhabitant of wet habitats - the frog. Its protective coloration allows it to lie in wait for the victim, but does not save it from another predator - the common grass snake. The heron, having caught the snake, closes the food chain in the floodplain meadow.
If the food chain begins with dead plant remains, corpses and animal excrement - detritus, it is called detritus, or decomposition chain. The term "detritus" means a decay product. It is borrowed from geology, where the products of the destruction of rocks are called detritus. In ecology, detritus is the organic matter involved in the decomposition process. Such chains are characteristic of the communities of the bottom of deep lakes and oceans, where many organisms feed on detritus formed by dead organisms from the upper illuminated layers of the reservoir.
In forest biocenoses, the detrital chain begins with the decomposition of dead organic matter by saprophage animals. Soil invertebrates (arthropods, worms) and microorganisms take the most active part in the decomposition of organic matter. There are also large saprophages - insects that prepare the substrate for organisms that carry out mineralization processes (for bacteria and fungi).
In contrast to the pasture chain, the size of organisms does not increase when moving along the detrital chain, but, on the contrary, decreases. So, gravedigger insects can stand on the second level. But most typical representatives detrital chain are fungi and microorganisms that feed on dead matter and complete the process of bioorganic decomposition to the state of the simplest mineral and organic substances, which are then consumed in dissolved form by the roots of green plants at the top of the pasture chain, thereby starting new circle movement of matter.
In some ecosystems, pasture chains predominate, in others, detrital chains. For example, a forest is considered an ecosystem dominated by detrital chains. In the rotting stump ecosystem, there is no grazing chain at all. At the same time, for example, in the ecosystems of the sea surface, almost all producers represented by phytoplankton are consumed by animals, and their corpses sink to the bottom, i.e. leave the published ecosystem. These ecosystems are dominated by grazing or grazing food chains.
General rule concerning any the food chain, states: at each trophic level of the community, most of the energy absorbed with food is spent on maintaining life, dissipated and can no longer be used by other organisms. Thus, the food consumed at each trophic level is not fully assimilated. A significant part of it is spent on metabolism. When moving to each subsequent link in the food chain total usable energy transferred to the next higher trophic level is reduced.
