Food chains examples from 4. Pasture and detritus chains

Autotrophs (producers)

Heterotrophs (consumers)

Destructors (reducers)

Levels of the food (trophic) chain

Types of food chains

Energy in the food chain

Food chain meaning

Types of food relationships

The importance of food relationships

First trophic level

Second trophic level

Third trophic level

Fourth trophic level

Fifth trophic level

Grassland food chain

Detrital food chain

Pasture chains

Detrital trophic relationships

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 raptors. Insects that eat other insects are also considered predators. Finally, there are omnivores (they eat both plant and animal foods).

What groups can animals be divided into based on their feeding methods? Fill out the chart.

Power circuits

Living things are connected to each other in a food chain. For example: Aspen trees grow in the forest. Hares eat their bark. A hare can be caught and eaten by a wolf. It turns out this food chain: aspen - hare - wolf.

Compose and write down power supply circuits.
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, cone
Answer: cone - chipmunk - hawk

Read short texts about animals from the book "With Love for Nature." Identify and write down the type of food animals eat.

In autumn, the badger begins to prepare for winter. He eats up and gets very fat. He eats everything he comes across: beetles, slugs, lizards, frogs, mice, and sometimes even small hares. He eats and wild berries, and fruits.
Answer: badger is omnivorous

In winter, the fox catches mice and sometimes partridges under the snow. Sometimes she hunts for 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

At the end of summer and autumn, the squirrel collects mushrooms. She pins them on tree branches so that the mushrooms dry out. The squirrel also stuffs nuts and acorns into hollows and cracks. All this will be useful to her during the winter lack of food.
Answer: squirrel is herbivorous

The wolf is a dangerous beast. In summer he attacks various animals. It also eats mice, frogs, and lizards. Destroys bird nests on the ground, eats eggs, chicks, and birds.
Answer: carnivorous wolf

The bear breaks up rotten stumps and looks for fatty larvae of woodcutter beetles and other insects that feed on wood. He eats everything: he catches frogs, lizards, in a word, whatever he comes across. Digs plant bulbs and tubers from the ground. You can often meet a bear in berry fields, where he greedily eats the berries. Sometimes a hungry bear attacks moose and deer.
Answer: the bear is omnivorous

Based on the texts from the previous assignment, compose and write down several power circuits.

1. strawberry - slug - badger
2. tree bark - hare - fox
3. grain - bird - wolf
4. wood - beetle larvae - woodcutter - bear
5. young shoots of trees - deer - bear

Draw a food chain using the pictures.

A food chain is a complex structure of links in which each of them is interconnected with the neighboring or some other link. These components of the chain are various groups of flora and fauna organisms.

In nature, a food chain is a way of moving matter and energy in an environment. All this is necessary for the development and “construction” of ecosystems. Trophic levels are a community of organisms located at a certain level.

Biotic cycle

The food chain is a biotic cycle that connects living organisms and inanimate components. This phenomenon is also called biogeocenosis and includes three groups: 1. Producers. The group consists of organisms that produce food substances for other creatures through photosynthesis and chemosynthesis. The product of these processes are primary organic substances. Traditionally, producers are the first in the food chain. 2. Consumers. The food chain has this group over producers, since they consume those nutrients, which the producers produced. This group includes various heterotrophic organisms, for example, animals that eat plants. There are several subspecies of consumers: primary and secondary. The category of primary consumers includes herbivores, and the secondary consumers include carnivores that eat the previously described herbivores. 3. Decomposers. This includes organisms that destroy all previous levels. A clear example This may be the case when invertebrates and bacteria decompose plant debris or dead organisms. Thus, the food chain ends, but the cycle of substances in nature continues, since as a result of these transformations mineral and other minerals are formed. useful substances. Subsequently, the formed components are used by producers to form primary organic matter. The food chain has a complex structure, so secondary consumers can easily become food for other predators, which are classified as tertiary consumers.

Classification

Thus, it takes a direct part in the cycle of substances in nature. There are two types of chains: detritus and pasture. As the names indicate, the first group is most often found in forests, and the second - in open spaces: field, meadow, pasture.

Such a chain has a more complex structure of connections; it is even possible for fourth-order predators to appear there.

Pyramids

one or more existing in a specific habitat form the paths and directions of movement of substances and energy. All this, that is, organisms and their habitats, form a functional system, which is called an ecosystem (ecological system). Trophic connections are rarely straightforward; they usually take the form of a complex and intricate network, in which each component is interconnected with the others. The interweaving of food chains forms food webs, which mainly serve for construction and calculations ecological pyramids. At the base of each pyramid is the level of producers, on top of which all subsequent levels are adjusted. There is a pyramid of numbers, energy and biomass.

TROPHIC CHAINS

Purpose of work: obtaining skills in compiling and analyzing food (trophic) chains.

General information

There are various connections between living organisms in ecosystems. One of the central connections, which cements a variety of organisms into one ecosystem, is food, or trophic. Food connections unite organisms with each other according to the food-consumer principle. This leads to the emergence of food or trophic chains. Within an ecosystem, energy-containing substances are created by autotrophic organisms and serve as food for heterotrophs. Food connections are mechanisms for transferring energy from one organism to another. A typical example is an animal eating plants. This animal, in turn, can be eaten by another animal. Energy transfer can occur in this way through a number of organisms.

Each subsequent one feeds on the previous one, which supplies it with raw materials and energy.

This sequence of transfer of food energy in the process of nutrition from its source through a successive series of living organisms is called food (trophic) chain, or power circuit. Trophic chains is a unidirectional flow path solar energy, absorbed during the process of photosynthesis, through living organisms of the ecosystem into the environment, where the unused part of it is dissipated in the form of low-temperature thermal energy.

mice, sparrows, pigeons. Sometimes in ecological literature any food connection is called a “predator-prey” connection, meaning that a predator is an eater. The stability of the predator-prey system is ensured by the following factors:

- ineffectiveness of the predator, flight of the prey;

- environmental restrictions imposed by the external environment on population size;

- availability of alternative food resources for predators;

- reducing the delay in the predator's reaction.

The location of each link in the food chain is trophic level. The first trophic level is occupied by autotrophs, or so-called primary producers. Organisms of the second trophic level are called first-

primary consumers, the third - secondary consumers, etc.

Trophic chains are divided into two main types: grazing (grazing chains, consumption chains) and editrite (decomposition chains).

Plant → hare → wolf Producer → herbivore → carnivore

The following food chains are also widespread:

Plant material (eg nectar) → fly → spider → shrew → owl.

Juice rose bush→ aphid → ladybug→ spider → insectivorous bird → bird of prey.

In aquatic, particularly marine, ecosystems, predator food chains are longer than in terrestrial ones.

The detrital chain begins with dead organic matter - detritus, which is destroyed by detritivores eaten by small predators, and ends with the work of decomposers that mineralize organic remains. Deciduous forests play an important role in the detrital food chains of terrestrial ecosystems, most of the foliage of which is not consumed by herbivores and is part of the forest litter. The leaves are crushed by numerous detritivores (fungi, bacteria, insects), then ingested by earthworms, which uniformly distribute humus in the surface layer of soil, forming a mull. Decomposing

microorganisms that complete the chain produce the final mineralization of dead organic residues (Fig. 1).

In general, typical detritus chains of our forests can be represented as follows:

leaf litter → earthworm → blackbird → sparrowhawk;

dead animal → carrion fly larvae → grass frog → grass snake.

Rice. 1. Detrital food chain (according to Nebel, 1993)

As a starting point organic material, which is subjected to biological processing in the soil by organisms inhabiting the soil; we can take wood as an example. Wood that falls on the soil surface is primarily processed by the larvae of longhorned beetles, borers, and borers, which use it for food. They are replaced by mushrooms, the mycelium of which primarily settles in the passages made in the wood by insects. Mushrooms further loosen and destroy the wood. Such loose wood and the mycelium itself turn out to be food for fireflower larvae. At the next stage, ants settle in the already severely damaged wood, destroying almost all the larvae and creating conditions for a new generation of fungi to settle in the wood. Snails begin to feed on such mushrooms. Decomposer microbes complete the destruction and humification of wood.

Similarly, there is humification and mineralization of manure from wild and domestic animals entering the soil.

As a rule, the food of every living creature is more or less varied. Only all green plants “feed” the same way: carbon dioxide and ions of mineral salts. In animals, cases of narrow specialization of nutrition are quite rare. As a result of a possible change in animal nutrition, all ecosystem organisms are involved in a complex network of food relationships. Food chains closely intertwined with each other, forming food or trophic networks. In a food web, each species is directly or indirectly connected to many. An example of a trophic network with the placement of organisms by trophic levels is shown in Fig. 2.

Food webs in ecosystems are very complex, and we can conclude that the energy entering them migrates for a long time from one organism to another.

Rice. 2. Trophic network

In biocenoses, food connections play a dual role. Firstly, they

provide the transfer of matter and energy from one organism to another.

Thus, species coexist together and support each other’s life. Secondly, food connections serve as a mechanism for regulating numerical

Representation of trophic networks can be traditional (Fig. 2) or using directed graphs (digraphs).

A geometrically oriented graph can be represented as a set of vertices, denoted by circles with vertex numbers, and arcs connecting these vertices. An arc specifies the direction from one vertex to another. A path in a graph is a finite sequence of arcs in which the beginning of each subsequent arc coincides with the end of the previous one. An arc can be designated by the pair of vertices that it connects. A path is written as a sequence of vertices through which it passes. A path is called a path whose starting vertex coincides with the final vertex.

FOR EXAMPLE:

B 3;

1, 2 or 1, 3, 2 – paths from the top

		to the top

In the power network, the top of the graph displays modeling objects; arcs, indicated by arrows, lead from the prey to the predator.

Any living organism occupies a certain ecological niche. An ecological niche is a set of territorial and functional characteristics of a habitat that meet the requirements of a given species. No two species have identical niches in ecological phase space. According to Gause's principle of competitive exclusion, two species with similar ecological requirements long time cannot occupy one ecological niche. These species compete, and one of them displaces the other. Based on power networks, you can build competition graph. Living organisms in the competition graph are displayed as vertices of the graph; an edge (a connection without direction) is drawn between the vertices if there is a living organism that serves as food for the organisms displayed by the above vertices.

The development of a competition graph allows one to identify competing species of organisms and analyze the functioning of the ecosystem and its vulnerability.

The principle of matching the growth in complexity of an ecosystem with increasing its stability is widely accepted. If the ecosystem is represented by a food network, you can use different ways Difficulty Dimensions:

- determine the number of arcs;

- find the ratio of the number of arcs to the number of vertices;

Trophic level is also used to measure the complexity and diversity of the food web, i.e. the place of the organism in the food chain. The trophic level can be determined both by the shortest and longest long chain nutrition from the vertex in question, which has a trophic level equal to “1”.

PROCEDURE FOR PERFORMANCE OF THE WORK

Task 1

Make a network for 5 participants: grass, birds, insects, hares, foxes.

Task 2

Establish the food chains and trophic level along the shortest and longest path of the food network from task “1”.

		Trophic level and food chain
power supply network	along the shortest path		along the longest path

4. Insects

Note: The grazing food chain begins with the producers. The organism listed in column 1 is the top trophic level. For consumers of the first order, the long and short paths of the trophic chain coincide.

Task 3

Propose a trophic network according to the task option (Table 1P) and make a table of trophic levels along the longest and shortest path. The food preferences of consumers are shown in Table. 2P.

Task 4

Make a trophic network according to Fig. 3 and place its members according to trophic levels

REPORT PLAN

1. Purpose of the work.

2. Food web graph and competition graph based on the training example (tasks 1, 2).

3. Table of trophic levels based on the educational example (task 3).

4. Food network graph, competition graph, table of trophic levels according to the assignment option.

5. Scheme of the trophic network with the placement of organisms by trophic levels (according to Fig. 3).

Rice. 3. Tundra biocenosis.

First row: small passerines, various dipterous insects, rough-legged buzzard. Second row: arctic fox, lemmings, polar owl. Third row: white partridge, white hares. Fourth row: goose, wolf, reindeer.

Literature

1. Reimers N.F. Nature management: Dictionary-reference book. – M.: Mysl, 1990. 637 p.

2. Animal life in 7 volumes. M.: Education, 1983-1989.

3. Zlobin Yu.A. General ecology. Kyiv: Naukova Dumka, 1998. – 430 p.

4. Stepanovskikh A.S. Ecology: Textbook for universities. – M.: UNITIDAN,

5. Nebel B. Science of environment: how the world works. – M.: Mir, 1993.

–t.1 – 424 p.

6. Ecology: Textbook for technical universities / L.I. Tsvetkova, M.I. Alekseev, etc.; Ed. L.I. Tsvetkova.–M.: ASV; St. Petersburg: Khimizdat, 2001.-552 p.

7. Girusov E.V. and others. Ecology and economics of environmental management: Textbook for universities / Ed. Prof. E.V. Girusova. – M.: Law and Law, UNITY,

		Table 1P
		Species structure of biocenosis
	Name bio-	Species composition of the biocenosis

	Cedarwood	Korean cedar, yellow birch, variegated hazel,
		sedge, white hare, flying squirrel, common squirrel,
		wolf, brown bear, Himalayan bear, sable,
		mouse, nutcracker, woodpecker, fern.
	swampy	Sedges, iris, common reed. A wolf, a fox come in,
		brown bear, roe deer, mouse. Amphibians – Siberian salamander
	reed grass	skiy, Far Eastern tree frog, Siberian frog. Ulit-
		ka, earthworm. Birds – Far Eastern White
		stork, piebald harrier, pheasant, red-crowned crane, white-naped beetle
		Ravl. Swallowtail butterflies.
	White birch	Aspen, flat-leaved birch (white) aspen, alder, dio-
		rather nipponica (herbaceous vine), grasses, sedges,
		forbs (clover, rank). Shrubs – Lespedeza, Rya-
		binnik, meadowsweet. Mushrooms – boletus, boletus.
		Animals - raccoon dog, wolf, fox, bear
		ry, weasel, wapiti, roe deer, Siberian salamander, frog-
		ka Siberian mouse. Birds – great spotted eagle, tit,

	Spruce grass-	Plants – fir, larch, Korean cedar, maple, rowan
		mountain ash, honeysuckle, spruce, sedges, cereals.
	shrubby	Animals – white hare, common squirrel, flying squirrel
		ha, wolf, brown bear, Himalayan bear, sable,
		kharza, lynx, wapiti, elk, hazel grouse, owl, mouse, butterfly

		Plants - Mongolian oak, aspen, birch,
		linden, elm, maakia (the only one in the Far East
		tree belonging to the legume family), shrubs –
		lespedeza, viburnum, mountain ash, wild rose,
		herbs – lily of the valley, sedge, hellebore, wild garlic, bells,
		bells. Animals – chipmunk, raccoon dog
		ka, wolf, fox, brown bear, badger, weasel, lynx, ka-
		ban, wapiti, roe deer, hare, Siberian salamander, tree frog
		Far Eastern, Siberian frog, mouse, lizard
		hawk, jay, woodpecker, nuthatch, woodcutter beetle, blacksmith

		Plants - aspen, birch, hawthorn, shi-
		povnik, spirea, peony, cereals. Animals – raccoon
		dog, wolf, fox, brown bear, weasel, wapiti, co-
		sulya, Siberian salamander, Siberian frog, mouse, lizard
		ritsa viviparous, jay, woodpecker, nuthatch, spotted eagle,
		woodcutter beetle, grasshopper,

		Table 2P
	Nutrition spectrum of some species

Living organisms		Food cravings - “menu”
	Grass (cereals, sedges); aspen, linden, hazel bark; berries (strawberries)

	Cereal seeds, insects, worms.
flying squirrel

	and their larvae.
Plants	Consume solar energy and minerals, water,
	oxygen, carbon dioxide.
	Rodents, hares, frogs, lizards, small birds.

Common squirrel	Pine nuts, hazelnuts, acorns, cereal seeds.
	Shrub seeds (Eleutherococcus), berries (lingonberries), insects
	and their larvae.
Insect larvae	Mosquito larvae – algae, bacteria.
wet mosquitoes,	Dragonfly larvae are insects and fish fry.
	Herbal juice.
	Rodents, hares, frogs, lizards.

Steller's sea eagle	Fish, small birds.

Brown bear	Euryphage, prefers animal food: wild boars (pork)
	ki), fish (salmon). Berries (raspberries, bird cherry, honeysuckle, pigeons)
	ka), roots.
Himalayan bear	Angelica (bear's pipe), wild berries (lingonberries, raspberries, cherry
	fly, blueberry), honey (wasps, bees), lilies (bulbs), mushrooms,
	nuts, acorns, ant larvae.
Insects	Herbaceous plants, tree leaves.

	Mouse, squirrel, hares, hazel grouse.
	Predator. Hares, squirrels, pigs.
		grass (wintering horsetail), legumes (vetch, china),
		hazel bark, willow bark, birch undergrowth, roots of shrubs (forest
	shina, raspberries).
	Buds of birch, alder, linden; cereals; rowan berries, viburnum; needles fir-
	you, spruce, larches.
	Mouse, chipmunk, hares, fox cubs, snakes (snake), lizard, white
	ka, bat.
	Mice, hares, roe deer, in a flock can kill deer, elk, and wild boar.
Earwig	Predator. Fleas, beetles (small), slugs, earthworms.
Woodcutter beetle	Bark of birch, cedar, linden, maple, larch.
	Plant pollen.
peacock eye
	Mouse, hares, chipmunk, Siberian salamander, crane chicks,
	stork, ducks; Far Eastern tree frog, baby pheasants, worms,
	large insects.
	Bark of hazel, birch, willow, oak, sedge, reed grass, reed; leaves are white
	cuts, willow, oak, hazel.
	Predator. Crustaceans, mosquito larvae.

Tree frog far-		Aquatic invertebrates.

		Grasses (reed grass), sedge, mushrooms, plant residues and soil.
		Plants, fish and their eggs during spawning, insects and their larvae

earthworm		Dead plant debris.
Far Eastern		Snail, tree frog, Siberian frog, fish (loach, sleeper), snakes,
white stork		mice, locusts, passerine chicks.
Japanese crane		Sedge rhizomes, fish, frogs, small rodents, chicks.
Pied harrier		Mouse, small birds (buntings, warblers, sparrows), frogs,
		lizards, large insects.
		Birch, alder, reed buds.
Swallowtail butterflies		Pollen from plants (violets, corydalis).
		Carnivorous, prefers animal food - hares, young
		moose calves, roe deer, deer, wild boars.
Raccoon co-		Rotten fish, birds (larks, fescue birds, warblers).

		Branch food (birch, aspen, willow, hazel; oak, linden leaves),
		acorns, oak bark, algae in shallow waters, three-leaf watch.
		Mosquito, spiders, ants, grasshoppers.

Lizard alive		Insects and their larvae, earthworms.

spotted eagle		Predator. Small mammals, pheasant, mice, hares, foxes,
		birds, fish, rodents.
		Squirrels, chipmunks, birds.
Chipmunk		Seeds of apple tree, rose hip, viburnum, field ash, mountain ash; mushrooms;
		nuts; acorns.
		Roots, earthworms, mice, insects (ants and their larvae).
		Predator. Mice.
		Cereal seeds, nuts.
		Pine nuts, acorns, berries (rowan), apple tree.
		Lumberjack beetles, wood-boring insects.
		Wild boar, hare, roe deer, elk calves, fawns, elk, deer (wounded animals).
Nuthatch		Insects; tree seeds, berries, nuts.
Lemmings		Granivores. Sedges, crowberry, cereals.
		Granivores.
		Predator. Lemmings, chicks of partridges, seagulls.
polar owl		Lemmings, mice, voles, hares, ducks, pheasants, black grouse.

Ptarmigan		Herbivores. Cereal seeds; buds of birch, willow, alder.
		Herbivores, leaves and bark of trees, moss - moss.
White hare		In winter - bark; in summer - berries, mushrooms.
		Herbivores. Sedges, grasses, algae, shoots of aquatic plants.
Reindeer		Resin moss, cereals, berries (cloudberries, cranberries), mice.
		Roe deer, wapiti, sika deer, wild boar.
Daphnia, Cyclops		Unicellular algae.

Every organism must receive energy to live. For example, plants consume energy from the sun, animals eat plants, and some animals eat other animals.

A food (trophic) chain is the sequence of who eats whom in a biological community () to obtain nutrients and energy that support life.

Autotrophs- living organisms that make their own food, that is, their own organic compounds, from simple molecules such as carbon dioxide. There are two main types of autotrophs:

Photoautotrophs (photosynthetic organisms), such as plants, process energy sunlight to receive organic compounds- sugars - from carbon dioxide in progress . Other examples of photoautotrophs are algae and cyanobacteria.

Chemoautotrophs obtain organic substances due to chemical reactions that involve inorganic compounds (hydrogen, hydrogen sulfide, ammonia, etc.). This process is called chemosynthesis.

Autotrophs are the basis of every ecosystem on the planet. They make up the majority of food chains and webs, and the energy obtained through photosynthesis or chemosynthesis supports all other organisms in ecological systems. When it comes to their role in food chains, autotrophs can be called producers or producers.

Heterotrophs, also known as consumers, cannot use solar or chemical energy to produce their own food from carbon dioxide. Instead, heterotrophs obtain energy by consuming other organisms or their byproducts. People, animals, fungi and many bacteria are heterotrophs. Their role in food chains is to consume other living organisms. There are many species of heterotrophs with different ecological roles, from insects and plants to predators and fungi.

Another consumer group should be mentioned, although it does not always appear in food chain diagrams. This group consists of decomposers, organisms that process dead organic matter and waste, turning them into inorganic compounds.

Decomposers are sometimes considered a separate trophic level. As a group, they feed on dead organisms coming from various trophic levels. (For example, they are able to process decaying plant matter, the body of a squirrel malnourished by predators, or the remains of a deceased eagle.) In a sense, the trophic level of decomposers runs parallel to the standard hierarchy of primary, secondary, and tertiary consumers. Fungi and bacteria are key decomposers in many ecosystems.

Decomposers, as part of the food chain, play an important role in maintaining a healthy ecosystem because they return nutrients and moisture to the soil, which are then used by producers.

Diagram of the levels of the food (trophic) chain

A food chain is a linear sequence of organisms that transfer nutrients and energy from producers to top predators.

The trophic level of an organism is the position it occupies in the food chain.

The food chain starts with autotrophic organism or producer, producing its own food from a primary energy source, usually solar or energy from hydrothermal vents at mid-ocean ridges. For example, photosynthetic plants, chemosynthetic plants, etc.

Next come the organisms that feed on autotrophs. These organisms are called herbivores or primary consumers and consume green plants. Examples include insects, hares, sheep, caterpillars and even cows.

The next link in the food chain are animals that eat herbivores - they are called secondary consumers or carnivorous (predatory) animals(for example, a snake that feeds on hares or rodents).

In turn, these animals are eaten by larger predators - tertiary consumers(for example, an owl eats snakes).

Tertiary consumers are eaten quaternary consumers(for example, a hawk eats owls).

Every food chain ends with a top predator or superpredator - an animal with no natural enemies (for example, a crocodile, polar bear, shark, etc.). They are the "masters" of their ecosystems.

When any organism dies, it is eventually eaten by detritivores (such as hyenas, vultures, worms, crabs, etc.) and the rest is decomposed by decomposers (mainly bacteria and fungi), and energy exchange continues.

Arrows in a food chain show the flow of energy, from the sun or hydrothermal vents to top predators. As energy flows from body to body, it is lost at each link in the chain. The collection of many food chains is called food web.

The position of some organisms in the food chain may vary because their diet is different. For example, when a bear eats berries, it acts as a herbivore. When it eats a plant-eating rodent, it becomes a primary predator. When a bear eats salmon, it acts as a superpredator (this is due to the fact that salmon is the primary predator because it feeds on herring, which eats zooplankton, which feeds on phytoplankton, which generate their own energy from sunlight). Think about how people's place in the food chain changes, even often within a single meal.

In nature, as a rule, there are two types of food chains: pasture and detritus.

Grassland food chain diagram

This type of food chain begins with living green plants to feed the herbivores on which carnivores feed. Ecosystems with this type of circuit are directly dependent on solar energy.

Thus, the grazing type of food chain depends on the autotrophic capture of energy and its movement along the links of the chain. Most ecosystems in nature follow this type of food chain.

Examples of grazing food chains:

Grass → Grasshopper → Bird → Hawk;
Plants → Hare → Fox → Lion.

Detrital food chain diagram

This type of food chain begins with decaying organic material - detritus - which is consumed by detritivores. Then, predators feed on detritivores. Thus, such food chains are less dependent on direct solar energy than grazing ones. The main thing for them is the influx of organic substances produced in another system.

For example, this type of food chain is found in decomposing litter.

Energy is transferred between trophic levels when one organism feeds on and receives nutrients from another. However, this movement of energy is inefficient, and this inefficiency limits the length of food chains.

When energy enters a trophic level, some of it is stored as biomass, as part of the body of organisms. This energy is available for the next trophic level. Typically, only about 10% of the energy that is stored as biomass at one trophic level is stored as biomass at the next level.

This principle of partial energy transfer limits the length of food chains, which typically have 3-6 levels.

At each level, energy is lost in the form of heat, as well as in the form of waste and dead matter that decomposers use.

Why does so much energy leave the food web between one trophic level and the next? Here are some of the main reasons for inefficient energy transfer:

At each trophic level, a significant portion of energy is dissipated as heat as organisms perform cellular respiration and move around in daily life.
Some organic molecules that organisms feed on cannot be digested and are excreted as feces.
Not all individual organisms in a trophic level will be eaten by organisms from the next level. Instead, they die without being eaten.
Feces and uneaten dead organisms become food for decomposers, who metabolize them and convert them into their energy.

So, none of the energy actually disappears - it all ends up producing heat.

1. Food chain studies help to understand feeding relationships and interactions between organisms in any ecosystem.

2. Thanks to them, it is possible to evaluate the mechanism of energy flow and the circulation of substances in the ecosystem, as well as understand the movement of toxic substances in the ecosystem.

3. Studying the food chain provides insight into biomagnification issues.

In any food chain, energy is lost every time one organism is consumed by another. In this regard, there should be much more plants than herbivorous animals. There are more autotrophs than heterotrophs, and therefore most of them are herbivores rather than carnivores. Although there is intense competition between animals, they are all interconnected. When one species goes extinct, it can affect many other species and have unpredictable consequences.

Food or trophic chain call the relationship between different groups of organisms (plants, fungi, animals and microbes), in which energy is transported as a result of the consumption of some individuals by others. Energy transfer is the basis for the normal functioning of an ecosystem. Surely these concepts are familiar to you from the 9th grade of school from the general biology course.

Individuals of the next link eat the organisms of the previous link, and this is how matter and energy are transported along the chain. This sequence of processes underlies the living cycle of substances in nature. It is worth saying that a huge part of the potential energy (approximately 85%) is lost when transferred from one link to another, it is dissipated, that is, dissipated in the form of heat. This factor is limiting in relation to the length of food chains, which in nature usually have 4-5 links.

Within ecosystems, organic matter is produced by autotrophs (producers). Plants, in turn, are eaten by herbivorous animals (first-order consumers), which are then eaten by carnivorous animals (second-order consumers). This 3-link food chain is an example of a proper food chain.

There are:

Trophic chains begin with auto- or chemotrophs (producers) and include heterotrophs in the form of consumers of various orders. Such food chains are widespread in land and marine ecosystems. They can be drawn and compiled in the form of a diagram:

Producers -> Consumers of the 1st order -> Consumers of the 1st order -> Consumers of the 3rd order.

A typical example is the food chain of a grassland (this could be forest zone, and the desert, in this case will only differ biological species various participants in the food chain and the ramifications of the network of food interactions).

So, with the help of the energy of the Sun, a flower produces nutrients for itself, that is, it is a producer and the first link in the chain. A butterfly that feeds on the nectar of this flower is a consumer of the first order and the second link. The frog, which also lives in the meadow and is an insectivorous animal, eats the butterfly - the third link in the chain, a consumer of the second order. The frog is swallowed by a snake - the fourth link and a consumer of the third order, the snake is eaten by a hawk - a consumer of the fourth order and the fifth, as a rule, the last link in the food chain. A person can also be present in this chain as a consumer.

In the waters of the World Ocean, autotrophs represented unicellular algae, can exist only as long as sunlight is able to penetrate through the water column. This is a depth of 150-200 meters. Heterotrophs can also live in deeper layers, rising to the surface at night to feed with algae, and in the morning again going to the usual depth, making vertical migrations of up to 1 kilometer per day. In turn, heterotrophs, which are consumers of subsequent orders and live even deeper, rise in the morning to the level of habitat of consumers of the first order in order to feed on them.

Thus, we see that in deep bodies of water, usually seas and oceans, there is such a thing as a “food ladder.” Its meaning is that organic substances that are created by algae in the surface layers of the earth are transported along the food chain to the very bottom. Taking this fact into account, the opinion of some ecologists that the entire reservoir can be considered a single biogeocenosis can be considered justified.

To understand what the detrital food chain is, you need to start with the very concept of “detritus.” Detritus is a collection of remains of dead plants, corpses and end products of animal metabolism.

Detrital chains are typical for communities of inland waters, deep lake bottoms, and oceans, many of whose representatives feed on detritus formed by the remains of dead organisms from upper layers or accidentally entering a body of water from ecological systems located on land, in the form of, for example, leaf litter.

Bottom ecological systems of oceans and seas, where there are no producers due to the lack of sunlight, can exist only due to detritus, the total mass of which in the World Ocean is over calendar year can reach hundreds of millions of tons.

Detritus chains are also common in forests, where a considerable part of the annual increase in biomass of producers cannot be consumed directly by the first link of consumers. Therefore, it dies, forming litter, which, in turn, is decomposed by saprotrophs and then mineralized by decomposers. Fungi play an important role in the formation of detritus in forest communities.

Heterotrophs that feed directly on detritus are detritivores. In terrestrial ecological systems, detritivores include some species of arthropods, in particular insects, as well as annelids. Large detritivores among birds (vultures, crows) and mammals (hyenas) are usually called scavengers.

In ecological systems of waters, the bulk of detritivores are aquatic insects and their larvae, as well as some representatives of crustaceans. Detritivores can serve as food for larger heterotrophs, which, in turn, can also later become food for consumers of higher orders.

The links in the food chain are otherwise called trophic levels. By definition, this is a group of organisms that occupies a specific place in the food chain and provides a source of energy for each of the subsequent levels - food.

Organisms I trophic level in pasture food chains there are primary producers, autotrophs, that is, plants, and chemotrophs - bacteria that use energy chemical reactions for the synthesis of organic substances. In detrital systems, there are no autotrophs, and the first trophic level of the detrital trophic chain forms detritus itself.

Last, V trophic level represented by organisms that consume dead organic matter and final decay products. These organisms are called destructors or decomposers. Decomposers are mainly represented by invertebrate animals, which are necro-, sapro- and coprophages, using residues, waste and dead organic matter for food. Also included in this group are saprophagous plants that decompose leaf litter.

Also included in the level of destructors are heterotrophic microorganisms that are capable of converting organic substances into inorganic (mineral) substances, forming final products - carbon dioxide and water, which return to the ecological system and re-enter the natural cycle of substances.

B – contour passing through vertices 2, 4,