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Covers how species interact with each other. For example, living things that cannot make their own food must eat other organisms for food. Competition is a relationship between living things that depend on the same resources. adaptation that makes an organism more fit to live in their environment. Producers, also known as autotrophs, make their own food. They make The second trophic level consists of organisms that eat the producers. that use sunlight and/or chemical compounds to produce their own food. Ecosystem: All of the organisms that live in a certain area and their Mutualism: Symbiotic relationship in which both species benefit from the.
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.
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.Ecological Relationships
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. 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.
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. Sometimes there are definite losers. The predator benefits and the prey is harmed lethally, but it is a short-term interaction.
In parasitism, the parasite does not usually kill its host, but just feeds on it for a long time while it is living. The interaction is seemingly neutral for one of the organisms. For example, a barnacle attached to a whale is able to travel thousands of miles collecting and filtering food from the moving water. But then again, maybe those little hitchhikers are actually creating a tiny amount of additional drag as the whale moves through the water and therefore the whale has to expend just a little bit of additional energy.
If so, that would be a negative impact for the whale. Often, further research reveals that what was originally thought to be neutral for one participant and therefore an example of commensalism, actually has a very subtle positive or negative impact, so the classification is no longer commensalism, but rather mutualism or parasitism.
Is a bird nest on a tree limb commensalism, or is there some slight advantage or disadvantage for the tree in having the nest there? It is possible to come up with plausible explanations either way; only detailed research could provide the necessary information to answer the question. Competition is an interesting example of interactions. When we're talking about their role in food chains, we can call autotrophs producers.
Heterotrophs, also known as other-feeders, can't capture light or chemical energy to make their own food out of carbon dioxide. Instead, heterotrophs get organic molecules by eating other organisms or their byproducts. Animals, fungi, and many bacteria are heterotrophs. When we talk about heterotrophs' role in food chains, we can call them consumers. As we'll see shortly, there are many different kinds of consumers with different ecological roles, from plant-eating insects to meat-eating animals to fungi that feed on debris and wastes.
Food chains Now, we can take a look at how energy and nutrients move through a ecological community.
Let's start by considering just a few who-eats-who relationships by looking at a food chain. A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another.
Let's look at the parts of a typical food chain, starting from the bottom—the producers—and moving upward. At the base of the food chain lie the primary producers. The primary producers are autotrophs and are most often photosynthetic organisms such as plants, algae, or cyanobacteria.
The organisms that eat the primary producers are called primary consumers. Primary consumers are usually herbivores, plant-eaters, though they may be algae eaters or bacteria eaters. The organisms that eat the primary consumers are called secondary consumers.
Secondary consumers are generally meat-eaters—carnivores. The organisms that eat the secondary consumers are called tertiary consumers. These are carnivore-eating carnivores, like eagles or big fish. Some food chains have additional levels, such as quaternary consumers—carnivores that eat tertiary consumers. Organisms at the very top of a food chain are called apex consumers.
Ecological interactions (article) | Ecology | Khan Academy
We can see examples of these levels in the diagram below. The green algae are primary producers that get eaten by mollusks—the primary consumers. The mollusks then become lunch for the slimy sculpin fish, a secondary consumer, which is itself eaten by a larger fish, the Chinook salmon—a tertiary consumer.
In this illustration, the bottom trophic level is green algae, which is the primary producer.