Ecological interactions (article) | Ecology | Khan Academy
An ecosystem is all the living organisms in an area along with the nonliving, once alive, such as bits of wood from trees, rotting plant material, and animal Feeding Relations Heterotrophs include animals, protists, and bacteria, or fungi. Individual organisms live together in an ecosystem and depend on one another. In fact All animals, all fungi, and some kinds of bacteria are heterotrophs and consumers. Plants, algae, and microscopic organisms such as phytoplankton and some These “win-win” symbiotic interactions are known as mutualism (+ +) . Biotic factors include plants, animals, and micro-organisms. The ecological relationships connecting all ecosystems make up the biosphere. Non-living components include non-living resources, such as space, and the non-living physical . Bacteria, fungi and actinomycetes are three main types of decomposers.
Predators can also be prey, depending on what part of the food chain you are looking at. For example, a trout acts as a predator when it eats insects, but it is prey when it is eaten by a bear. It all depends on the specific details of the interaction. Ecologists use other specific names that describe what type of food a consumer eats: Omnivores eat both animals and plants.
Once again, knowing the Latin root helps a lot: For example, an insectivore is a carnivore that eats insects, and a frugivore is an herbivore that eats fruit. This may seem like a lot of terminology, but it helps scientists communicate and immediately understand a lot about a particular type of organism by using the precise terms.
Not all organisms need to eat others for food and energy. Some organisms have the amazing ability to make produce their own energy-rich food molecules from sunlight and simple chemicals. Organisms that make their own food by using sunlight or chemical energy to convert simple inorganic molecules into complex, energy-rich organic molecules like glucose are called producers or autotrophs. Some producers are chemosynthesizers using chemicals to make food rather than photosynthesizers; instead of using sunlight as the source of energy to make energy-rich molecules, these bacteria and their relatives use simple chemicals as their source of energy.
Chemosynthesizers live in places with no sunlight, such as along oceanic vents at great depths on the ocean floor. No matter how long you or a giraffe stands out in the sun, you will never be able to make food by just soaking up the sunshine; you will never be able to photosynthesize.
Producers use the food that they make and the chemical energy it contains to meet their own needs for building-block molecules and energy so that they can do things such as grow, move, and reproduce. All other life depends on the energy-rich food molecules made by producers — either directly by eating producers, or indirectly by eating organisms that have eaten producers.
Not surprisingly, ecologists also have terms that describe where in the food chain a particular consumer operates. A primary consumer eats producers e. And it can go even further: A single individual animal can act as a different type of consumer depending on what it is eating. When a bear eats berries, for example, it is being a primary consumer, but when it eats a fish, it might be a secondary or a tertiary consumer, depending on what the fish ate!
All organisms play a part in the web of life and every living thing will die at some point. This is where scavengers, detritivores which eat detritus or parts of dead thingsand decomposers come in. They all play a critical role that often goes unnoticed when observing the workings of an ecosystem. They break down carcasses, body parts and waste products, returning to the ecosystem the nutrients and minerals stored in them.
This interaction is critical for our health and health of the entire planet; without them we would be literally buried in dead stuff.
THE ECOSYSTEM: INTERRELATIONSHIPS BETWEEN
Crabs, insects, fungi and bacteria are examples of these important clean-up specialists. Another category of interactions between organisms has to do with close, usually long-term interaction between different types of organisms.
These interactions are called symbiosis. The impacts of symbiosis can be positive, negative, or neutral for the individuals involved. Organisms often provide resources or services to each other; the interaction is mutually beneficial.
For example, ants living in a tree may protect the tree from an organism that would like to make the tree its next meal, and at the same time the tree provides a safe home for the ants. Symbiotic relationships are not always positive for both participants. Heterotrophs which means "nourished by others"also called consumers, are organisms that consume other organisms.
Heterotrophs include animals, protists, and bacteria, or fungi. Animals that eat plants, such as deer and caterpillars, are called herbivores. Animals that eat other animals, such as mountain lions and wasps, are called carnivores. Decomposers are heterotrophs that feed from the carcasses of dead animals or dead plants. If they are animals, such as millipedes, lobsters, starfish, clams, and catfish, scientists sometimes call them scavengers.
Many animals, including starfish, lions, hyenas, and humans, change from carnivore to scavenger and back, depending on what food source is available. Some of the most important decomposers are nearly invisible. These are the detritivores: Each year, detritivores break down the remains of millions of tons of dead plant and animal material, recycling nutrients back into ecosystems around the world.
BBC Bitesize - GCSE Biology (Single Science) - Classification - Revision 1
Because animals eat one another, they can be linked in food chains, where, for example, a hawk eats a snake, which has eaten a ground squirrel, which has eaten a seed. Every ecosystem has numerous food chains that interlink to form a food web. A food web can change over time. In one year, a population explosion of oak moths means that insect predators focus on oak moth caterpillars.
In another year, oak moths are rare, and predators eat a diversity of other herbivores. Ecologists assign the organisms in a food web to different trophic levels, depending on where they get their energy. Plants, which get their energy A temperate rain forest. Rain forests have more organisms per square meter than any other ecosystem.
Predators that eat the birds would be in a fourth trophic level. Predators may eat at more than one level. Humans are an example. Productivity and Nutrient Cycling Every ecosystem is unique, yet similar ecosystems share fundamental characteristics, including climate, productivity, total mass of living organisms, and numbers of species. For example, tropical rain forests have higher species diversity than temperate forests. In the same way, marshes all have high productivity and deserts all have low productivity.
Primary productivity is the amount of energy captured by primary producers during photosynthesis on a square meter of land each year. One factor that determines productivity is latitude and its effect on sunshine. A square meter of land near the North Pole, for example, receives aboutkcals kilocalories of sunshine per year, while the same area at the equator receives nearly 2.
So all things being equal, the tropical region has the potential for higher productivity. However, even in the same latitude, primary productivity varies enormously from ecosystem to ecosystem. A marsh, for example, is twice as productive as a temperate forest, four times as productive as a wheat field, and thirty-five times as productive as a desert.
Another important characteristic of ecosystems is total biomass, the dry weight of all the organisms living in it.
Rain forests have more organisms per square meter and therefore more total biomass than other ecosystems, more even than the superproductive marshes. On land, the biomass of plants is usually greater than the biomass of herbivores, which is greater than the biomass of carnivores. The reason for this is that every chemical process releases energy in the form of heat.
So producers can use only part of the energy from the sun to build their bodies; the rest is lost as heat.