Name: food chains and energy flow
Uploaded: 2025-10-23T11:48:57.000Z
Duration: 1 min 35 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Life Science

interdependent-relationships-in-ecosystems

Interdependent Relationships in Ecosystems

3.1.9-12.I

Trophic Levels

- [Professeur] Au sein d'un écosystème, les espècessont organisées en chaînes alimentaires,un ordre séquentiel dans lequel l'énergie et les nutrimentssont transférés entre différents organismes. 
Chaque espèce appartient à une zone particulièreappelée "niveau alimentaire". 
Le niveau le plus bas est constituéde producteurs primaires, les organismesautotrophes qui obtiennent de l'énergiequ'ils synthétisent et transforment en matière organiqueà partir d'une source énergétique abiotique,comme le soleil. 
Tous les niveaux supérieurs sont constitués d'hétérotrophes,qui tirent leur énergie d'autres organismes. 
Le premier niveau est constitué de consommateurs primaires,se nourrissant directement de producteurs primaires. 
Plus haut, les consommateurs secondaires qui se nourrissentde consommateurs primaireset qui sont ensuite mangés par les consommateurs tertiaires. 
Cependant, les organismes n'appartiennent pas toujoursexclusivement à une de ces catégories. 
Par exemple, le faucon est à la fois consommateur secondairese nourrissant d'oiseaux granivoreset consommateur tertiaire se nourrissant de serpents,qui se nourrissent parfois eux-mêmes d'oiseaux granivores. 
Les décomposeurs, champignons, bactéries et détritivores,constituent le dernier niveau trophique. 
Ils se nourrissent des dépouilles d'autres organismeset rentrent dans tous les niveaux de la chaîne alimentaire.

Ripple, William J., Robert L. Beschta, Jennifer K. Fortin et Charles T. Robbins. « Cascades trophiques des loups aux grizzlis à Yellowstone. » Journal d’écologie animale 83, n° 1 (2014) : 223-33. [<a href="https://doi.org/10.1111/1365-2656.12123 » target="__blank">Sources</a>]

niveaux trophiques

Tous les organismes d’un écosystème occupent un niveau trophique dans la chaîne alimentaire. Le niveau le plus bas est celui des producteurs primaires, qui synthétisent leurs aliments à partir de l’énergie solaire ou chimique. Chaque niveau suivant obtient de l’énergie à partir des niveaux en dessous. Les détritivores peuvent occuper n’importe lequel des niveaux en dessus des producteurs primaires.
 
 <h4>Chaînes alimentaires</h4>
 
 Au sein d’un écosystème, l’énergie et les nutriments traversent les organismes dans un ordre séquentiel connu sous le nom de chaîne alimentaire. Chaque organisme occupe un niveau trophique ou une place spécifique dans cette chaîne alimentaire. Le niveau trophique le plus bas se compose d’organismes autotrophes. Les organismes autotrophes synthétisent leurs aliments en transformant l’énergie des produits chimiques — chimioautotrophes — ou du soleil — photoautotrophes. Les organismes des niveaux suivants — hétérotrophes — obtiennent de l’énergie à partir d’autres organismes dans les niveaux inférieurs. Le deuxième niveau trophique comprend les consommateurs primaires, les herbivores, qui consomment des autotrophes, les producteurs primaires, tandis que les troisième et quatrième niveaux sont composés de consommateurs secondaires et tertiaires, les carnivores. Les prédateurs ultimes occupent le niveau trophique supérieur de cette chaîne. Les décomposeurs, ou détritivores, habituellement des bactéries ou des champignons qui consomment des organismes morts, peuvent exister à n’importe quel niveau hétérotrophe et jouer un rôle essentiel dans le recyclage des nutriments et de la matière dans l’écosystème. Ces organismes sécrètent des enzymes digestives qui décomposent les matières organiques, les transformant en composés inorganiques qui peuvent être utilisés à nouveau par les producteurs primaires.
 
 <h4>Réseaux alimentaires</h4>
 
 Les chaînes alimentaires ne représentent pas toujours avec précision les interactions entre les espèces d’un écosystème. Les prédateurs et les proies peuvent exister à plusieurs niveaux trophiques. Un réseau alimentaire — un modèle holistique dans lequel toutes les interactions sont prises en compte — peut mieux décrire la complexité des relations dans un écosystème.

Niveaux trophiques

Tous les organismes d’un écosystème occupent un niveau trophique dans la chaîne alimentaire. Le niveau le plus bas est constitué de producteurs primaires, qui synthétisent leurs aliments à partir de ...

Education

Enseignement

JoVE Core

Biology

Biologie

Ecology

Écologie

Ecosystems

Écosystèmes

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

food chains and energy flow

Food chains show how energy and nutrients move through an ecosystem. Each organism holds a trophic level, or a specific place in that chain. The lowest level includes primary producers, which make their own food using energy from the sun or from chemicals.

Organisms at the next levels are heterotrophs, which get energy from other organisms below them. Primary consumers are herbivores, and they feed on autotrophs, also called primary producers. Secondary and tertiary consumers are carnivores that occupy the third and fourth trophic levels. Apex predators sit at the top of the chain.

Detritivores, also called decomposers, can live at any heterotrophic level. They are usually bacteria or fungi that feed on dead organisms. They release digestive enzymes that break down organic material into inorganic compounds. Primary producers can use these compounds again, so detritivores help recycle nutrients and matter in the ecosystem.

Food chains do not always show every interaction in an ecosystem. Predators and prey can be part of more than one trophic level. A food web gives a more complete picture because it includes all of these connections. It shows the complex relationships among species more clearly than a single food chain.

Food Chains and Energy Flow

what is an ecosystem?

Ecosystem Zones and Climate

Ecosystems are shaped by living and nonliving parts of an environment, and they can be grouped as terrestrial or aquatic. Terrestrial ecosystems depend on climate. Aquatic ecosystems are divided into freshwater and marine systems, and depth affects water temperature and how much sunlight reaches the water. Terrestrial ecosystems are called biomes. A biome is defined by climate and by the organisms that live there. Near the equator, rainforests have high, aseasonal temperatures and high annual...

trophic levels

Food chains show how energy and nutrients move through an ecosystem. Each organism holds a trophic level, or a specific place in that chain. The lowest level includes primary producers, which make their own food using energy from the sun or from chemicals. Organisms at the next levels are heterotrophs, which get energy from other organisms below them. Primary consumers are herbivores, and they feed on autotrophs, also called primary producers. Secondary and tertiary consumers are carnivores...

primary production

GPP, NPP, and Ecosystem Energy

Gross primary production and net primary production describe how energy enters and moves through ecosystems. Primary producers, or autotrophs, make their own food. They can do this by photosynthesis or chemosynthesis, and they can also gain energy by consuming other organisms. The rate at which producers capture and store this energy is called gross primary production, or GPP. Not all of the energy in GPP stays available to the rest of the ecosystem. Primary producers use some energy for...

production efficiency

Energy Transfer as Biomass Efficiency

Net production efficiency shows how much energy organisms turn into biomass for the next trophic level. It focuses on the usable energy stored in body tissue, not the energy lost as heat or excreted wastes. This makes it a key idea for understanding energy flow through ecosystems. As energy moves from one organism to the next, only biomass can serve as food for the next trophic level. The rest of the energy is used in metabolism and is lost over time. Net production efficiency, or NPE, is the...

trophic efficiency

Energy Loss in Food Chains

Trophic level transfer efficiency describes how much energy moves from one level of a food chain to the next. It shows why energy drops sharply as organisms eat and are eaten. In most ecosystems, only about 10% of the energy passes on. This energy loss follows the second law of thermodynamics. In living systems, much of the energy is lost as metabolic heat during respiration. Trophic level transfer efficiency, or TLTE, measures this transfer by comparing the energy produced at one trophic...

what are biogeochemical cycles?

Nutrient Recycling in Ecosystems

Nutrient recycling in ecosystems keeps the elements needed for life moving through living and nonliving parts of the environment. Elements such as water, carbon, nitrogen, sulfur, and phosphorus are present in limited amounts, so they must be conserved and reused. These movements are called biogeochemical cycles. These nutrients can exist in several chemical forms. They may spend long periods in the atmosphere, on land, under the land, or in aquatic environments. Decomposition is a key part of...

the water cycle

Water Movement Through Earth Systems

Water movement through Earth systems connects the hydrosphere, the atmosphere, the land, and living things. The hydrosphere includes every place where water is stored or moves. Because water supports living processes, its movement is important for ecosystem dynamics. The cycle starts when the sun warms surface water on land and in the oceans. That water evaporates and enters the atmosphere as vapor. Water can also move into the air by sublimation, which is ice changing directly into vapor, and...

the carbon cycle

Carbon Movement in Living Systems

Carbon moves through living systems and Earth over short and long time scales. It is the basis of all organic matter on Earth, and it cycles through ecosystems by passing between organisms and by moving through rocks, oceans, and the atmosphere. Human activities, including farming and burning fossil fuels, have changed this balance. In the biological carbon cycle, carbon dioxide in the atmosphere reacts with water to form bicarbonate. Primary producers, or autotrophs, use carbon dioxide and...

the nitrogen cycle

Nitrogen in Soil and Living Things

Nitrogen in soil and living things moves through ecosystems in several forms. Nitrogen atoms are found in proteins and DNA. Most animals and plants cannot use nitrogen gas, which is the main form of nitrogen on Earth. Nitrogen must first be changed into a usable form by nitrogen-fixing bacteria before it can move through food webs. About 78% of the air we breathe is nitrogen gas, but few organisms can use it in that form. Nitrogen fixation changes nitrogen gas (N2) into ammonia (NH3).

the phosphorus cycle

Phosphorus Movement in Soil and Water

Phosphorus moves through ecosystems mostly as phosphate ions in soil, water, sediment, and rocks. Unlike carbon, water, and nitrogen, it is not found in the atmosphere as a gas. It is also often a limiting nutrient, which means it is in short supply in many environments. Phosphorus is important in DNA, cell membranes, bones, and teeth. It is found in minerals, sediment, volcanic ash, and aerosols. As rocks and sediment weather over time, they release inorganic phosphate. That phosphate then...

the sulfur cycle

Sulfur in Ecosystems and Acid Rain

Sulfur moves through ecosystems as part of the chemical cycle that supports life. It is an important element in proteins and in amino acids such as cysteine, which helps give proteins their structure. On land, sulfur reaches ecosystems in several ways. Weak sulfuric acid can fall with precipitation, sulfur can drop directly from the atmosphere, rocks can weather and release sulfur, and geothermal vents can add it as well. Plants and microorganisms take sulfur up from the soil and change it...

bioremediation

Bioremediation in Soil and Oil Cleanup

Bioremediation uses prokaryotes, fungi, or plants to remove pollutants from the environment. It is a practical way to reduce harmful chemicals in contaminated soil and water. In agriculture, fertilizers and pesticides can leach into groundwater, streams, and lakes. Microbes and bacteria can help break down these toxins. One example is atrazine, an environmental toxin found in many fertilizers, which can be removed from soils by the bacterial species Rhizobium and Tricoderma sp. Bioremediation...

key terms and concepts

Explore how energy moves through food chains, from primary producers to apex predators, and how decomposers and food webs shape ecosystem relationships.

Food Chains and Energy Flow | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

La collection JoVE Core Biologie donne vie à la biologie à travers plus de 300 leçons vidéos animées concises et faciles à comprendre qui expliquent les concept clés de la biologie, mais aussi plus de 150 vidéos de scientifiques à l'action effectuant des expériences de recherche dans des laboratoires modernes.

matter-and-energy-in-organisms-and-ecosystems

Matter and Energy in Organisms and Ecosystems

3.1.9-12.H

Louisiana Student Standards for Science

High School

Life Sciences

ecosystems-interactions-energy-and-dynamics

Ecosystems: Interactions, Energy And Dynamics

HS-LS2-1

Environmental Science

HS-LS2-4

HS-LS2-6

Tennessee Academic Standards

Ecosystems: Interactions, Energy, and Dynamics

BIO1.LS2.4

Virginia  Standards of Learning

HIgh School

BIO.8

BIO.8.b

LS.5

LS.5.b

LS.6

LS.6.a

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Arizona Science Standards

HS.L2

HS.L2U1.19

Alabama Course of Study Science

Ecosystems: Interactions Energy and Dynamics

9-12.B.2.6

9-12.EVS.1.1

Next Generation Science Standards

Florida Department of Education

SC.912.L.17

SC.912.L.17.9

Texas Essential Knowledge and Skills

BIO.13

BIO.13.B

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

B-LS2-1.

B-LS2-2.

Georgia Standards of Excellence

SEV1.

SEV1.b

new-york-state-science-learning-standards

New York State Science Learning Standards

HS-LS2-3.

HS-LS2-4.

Entomology

SEN1.

SEN1.d

Oceanography

SO3.

SO3.2

SEC1.

SEC1.a

SB5.b

myJoVE Corporation

What is an Ecosystem?

Overview

An ecosystem is the interaction between all abiotic and biotic factors in an environment and can be classified as terrestrial or aquatic. ...

All organisms in an ecosystem occupy a trophic level in the food chain. The lowest level consists of primary producers, which synthesize their food from ...

Primary Production

The total amount of energy acquired by primary producers in an ecosystem is called gross primary production (GPP). However, of this energy, producers use ...

Production Efficiency

Net production efficiency (NPE) is the efficiency at which organisms assimilate energy into biomass for the next trophic level. Due to low metabolic rates ...

Trophic Efficiency

Trophic level transfer efficiency (TLTE) is a measure of the total energy transfer from one trophic level to the next. Due to extensive energy loss as ...

Life Histories

Constrained by limited energy and resources, organisms must compromise between offspring quantity and parental investment. This trade-off is represented ...

Energy Budgets and Reproductive Strategies

Organisms must balance energy intake with the energy required for growth, maintenance, and reproduction. These trade-offs result in a variety of ...

Population Growth

Population size is dynamic, increasing with birth rates and immigration, and decreasing with death rates and emigration. In ideal conditions with ...

Ecological Niches

All organisms have a position within an ecosystem. The complete set of living and nonliving factors&#x2014;including food resources, climate, and ...

Ecological Succession

Ecological succession is influenced by the processes of facilitation, inhibition, and toleration. Facilitation occurs when early successional species ...

Keystone Species

Measures of species biodiversity, such as richness (i.e., the number of species present) and evenness (i.e., their relative abundance), describe an ...

Symbiosis

Symbiotic relationships are long-term, close interactions between individuals of different species that affect the distribution and abundance of those ...

Competition

When organisms require the same limited resources within an environment, they may have to compete for them. Competition is a net-negative interaction. ...

Predator-Prey Interactions

Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction ...

Ecological Disturbance

An ecological disturbance is a temporary disruption in the environment resulting from abiotic, biotic, or anthropogenic factors, causing a pronounced ...

Students who demonstrate understanding can use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.  Assessment Boundary: Assessment does not include deriving mathematical equations to make comparisons.

What are Populations and Communities?

Populations are groups of individuals of the same species that inhabit a shared environment. Communities include multiple co-existing, interacting ...

Distribution and Dispersion

Ecology is the study of how organisms interact with their environment and with one another. An important aspect of ecology is understanding where species ...

Students who demonstrate understanding can use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales. Assessment Boundary: Assessment is limited to provided data.

3.1.9-12.L

Students who demonstrate understanding can evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, but changing conditions may result in a new ecosystem. Assessment Boundary: N/A

3.1.9-12.M

What is Weather?

Overview

Weather refers to the current state of atmospheric conditions at a specific time and place. Weather is temporary and is influenced by the ...

What is Climate?

Climate refers to the prevailing weather conditions in a specific area over an extended period. As the saying goes, &#8220;Climate is what you expect. ...

Global Climate Change

Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global ...

Conservation of Declining Populations

Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent ...

Habitat Fragmentation

Habitat fragmentation describes the division of a more extensive, continuous habitat into smaller, discontinuous areas. Human activities such as land ...

What is Biodiversity?

Biodiversity describes the variety of living things at multiple organizational levels: genetic, species and ecosystem diversity. Species diversity ...

Threats to Biodiversity

There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species ...

Biodiversity and Human Values

Human civilization relies on biodiversity in many ways. Sudden changes in species biodiversity result in environmental changes that can modify weather ...

What is Conservation Biology?

Conservation biology is a scientific field that focuses on the preservation of biodiversity in order to protect ecosystems while meeting the needs of the ...

Sustainable Development

As the human population continues to grow and use resources, we must be mindful of our planet&rsquo;s natural limits. Sustainable development provides a ...

Conservation of Small Populations

Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens ...

Externalities

Externalities are outcomes of economic activities that affect third parties who are not directly involved in it. These impacts can be either positive or ...

Private Cost and Benefit

Private cost is the expenses a business incurs while producing a good or the price paid by an individual in purchasing a good.
For example, consider a ...

Social Cost and Benefit

Private costs and benefits are the financial impacts on individuals or businesses directly involved in a transaction.
However, when an additional unit of ...

Negative Externalities

A negative externality is a cost suffered by an unrelated third party due to an economic transaction.
The costs created by negative externalities are not ...

Positive Externalities

Positive externalities occur when a third party benefits from an economic transaction without being directly involved.
Take vaccines as an example. When ...

The Efficient Level of Pollution

Producing goods often results in pollution as a byproduct, but eliminating all pollution isn&#39;t practical. Doing so would mean halting the production ...

Students who demonstrate understanding can design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity. Assessment Boundary: N/A

3.1.9-12.N

Food Chains and Energy Flow

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