We’ve just finished learning a lot about the Earth, from the layers of the Earth, to the atmosphere, and even its interactions with other bodies in space! However, what we haven’t looked at yet are the things that we share our planet with...our organisms!

Ecology is the study of relationships between organisms, which are living things, and their environments. It studies ecosystems, which are all of an organism’s environmental factors, living and nonliving, in a certain area that work together and interact with each other. Ecosystems can be of any size, from your backyard all the way up to the biosphere, which is all of Earth’s ecosystems combined. The biosphere consists of every part of the Earth where all organisms can survive, such as the Earth’s crust, the atmosphere, landforms, waterways, and forests. Every ecosystem is made up of different environmental factors. Biotic factors are living and once-living parts of an ecosystem, while Abiotic factors are the nonliving parts of an ecosystem.

First, let’s dive deeper into the abiotic factors of an ecosystem which are very necessary for survival. Air is the first key abiotic factor we’re going to discuss, and it is made up of the atmosphere that surrounds the Earth. Animals breathe in oxygen from the air and exhale carbon dioxide, while plants use carbon dioxide for essential purposes, such as photosynthesis, and releases oxygen back into the environment as a waste product. The oxygen and carbon dioxide that plants and animals release into the air are what allow them to coexist.

Another important abiotic factor is water, as almost all life processes, such as photosynthesis, respiration, and digestion, involve water. Plants and animals rely on water not only to drink, but for shelter as well, since water is a habitat for fish, frogs, seaweed, and many other organisms.

Soil is another crucial abiotic factor for these organisms. Soil consists of a mixture of rock and mineral particles, water, and dead organisms. However, each soil will have a different quantity of each substance, which allows different soils to have different nutrient qualities. And because of these different nutrient qualities, different soils support different types of plant life.

The next abiotic factor is sunlight. Plants and algae capture the sun’s energy and use it to produce chemical energy in the form of sugars. Animals then eat plants to get energy, which makes sunlight the principal source of energy for all organisms.

Finally, we have temperature and climate. Most animals and plants can only survive at a certain temperature range, as well as certain weather conditions, which make up the climate of a location. Temperature is affected by the amount of sunlight a region receives, the angle of that sunlight, the elevation of the ecosystem, whether or not large bodies of water are nearby, as well as ocean circulation. Climate is also affected by the timing and the amount of wind and precipitation an ecosystem receives.

All of these abiotic factors work together to create unique ecosystems for organisms, but now, let’s look at the organisms themselves, the biotic factors.

Each organism has its own role in an ecosystem, known as a “niche”. Furthermore, organisms all have their own living environments, called “habitats.” A population within an ecosystem would be the total number of organisms of a species that live in an area, or ecosystem. Finally, a community of organisms is made up of different populations of species living in an area.

Whew, that was a lot of information! In the next video, we will be talking about relationships between organisms, and how you can organize ecosystems. See you then!

In the wild, it’s survival of the fittest. Eat or be eaten. However, while there is so much competition in nature, organisms aren’t entirely on their own. Let’s take a look at how organisms compete with each other, but also how they help each other in various ways.

So, organisms don’t just exist together in an ecosystem. As a matter of fact, they actually depend on each other. This is called interdependence, which is the reliance on other populations for survival within a community. Populations of organisms exist in constantly shifting balances, and relationships between these populations can change them in several ways.

One way that relationships between populations can change numbers of organisms is through competition. Different organisms within an ecosystem compete for the same resources, such as water, space, and sunlight. Therefore, well-adapted members of a community are more likely to survive and reproduce after heavy competition for resources, compared to organisms that are less adapted to their environment.

Another impact that populations have on each other is through predation, in other words, predator prey relationships. Predators are animals that eat other animals, while prey are the animals being eaten by the predators. This means that if there is a lot of prey within a certain area, for example, squirrels in the woods, predators, such as foxes, will have more food to eat. Therefore, foxes will hunt and catch these squirrels, have them as meals, and then increase their own numbers. So the predators will increase, while the prey decreases. However, there will come a point where there isn’t enough prey left to feed an entire population of predators, which means that the number of foxes will decrease as well. And then, because of this decrease in foxes, due to a lack of predators, squirrels will once again increase their numbers. Because of this, foxes will begin to eat more squirrels and will grow in population, and the cycle will continue to go on and on and on.

Now, one way that a population can help sustain itself, without depending on other populations, is through cooperation, where members of a population cooperate to survive. For example, wolves hunt in packs, and lions hunt in prides, to capture and share food and to help each other survive. Similarly, birds call to each other, in order to signal the arrival of predators, which helps prey survive as well.

At this point, it seems like it’s every species for themselves, right? It seems as though the only animal another organism can trust is another animal from their species, and that too, only some of the time. However, this is actually not the case. Sometimes, organisms from different species interact with each other in a way that benefits one or both of them. These relationships are called symbiotic relationships, or symbiosis.

Now, there are three types of symbiosis: mutualism, commensalism, and parasitism.

In mutualism, both species benefit from associating with each other. Think of it as a win-win situation! For example, an oxpecker is a bird in the serengeti that eats the ticks attached to zebras. This benefits both organisms because the oxpeckers get food, while the zebras get cleaned, and get rid of any pests.

Meanwhile, in commensalism, one species benefits from the relationship while it doesn’t really have an effect on the other one, a win-neutral situation. An example of this is between clownfish and sea anemones. Clownfish are resistant to stings from sea anemones, while these sea anemones have a harmful effect on predators and other fish. Therefore, it uses the sea anemone for protection and shelter, benefiting from this relationship. However, the sea anemone doesn’t gain or lose anything from the relationship, as it is neither harmed nor benefited.

Finally, there is parasitism, a win-lose situation. One organism benefits while the other is harmed. The organism that benefits is the parasite, which feeds off of the organism that gets harmed, the host. One example of this is between hookworms and their hosts, which are usually dogs or humans. These hookworms then feed off of nutrients from their hosts. While the hookworm feeds itself and helps itself survive through these nutrients, its host will lose the nutrients, which are valuable for it as well. This is what makes this relationship a parasitic relationship.

There we have it, all of the different relationships between organisms. Though nature is cruel, some organisms might be lucky enough to have others to help them, through any of the symbiotic relationships, or cooperation. In the next lesson, we will talk more about the classic “eat or be eaten” scenarios...feeding relationships. See you then!

Now, we know enough about our ecosystems and the organisms that inhabit them. However, these ecosystems are facing a dangerous threat...and this threat is our very own human activities. It is time to understand that these ecosystems need our help, so, let’s talk about just how harmful human activities are, and what we can do to prevent them and help our ecosystems survive.

See, our Earth has limited natural resources. A natural resource is anything found in nature that is useful to us and to animals. These can range from water, sunlight, food, and air, to cotton, crude oil, gold, and trees. Within these natural resources are renewable and nonrenewable resources. While renewable resources are replaced by nature quickly, within 100 years or so, nonrenewable resources are those that take millions of years to replace.

The vast majority of the energy we use comes from fossil fuels...a nonrenewable resource. Once we burn these fossil fuels, they’re gone, and take millions of years to replace. On top of that, the burning of fossil fuels causes all types of pollution, which is our biggest impact on the planet. And through fossil fuels as well as loads of other activities, we create various different types of pollution too.

First, there’s soil pollution and erosion. By cutting down trees and plowing fields, we leave land more prone to erosion, which is the wearing away of soil by rain, rivers, and winds. Erosion washes away loose soil, which ends up in rivers, streams, and clouds water. This means that freshwater plants won’t have enough sunlight for photosynthesis, which is detrimental to the entire food chain.

Speaking of clouding the water, harmful chemicals from our homes, farms, and factories also get into water sources, creating water pollution. When the ocean water gets contaminated and clouded, thousands of organisms, such as water birds and fish, get killed.

Finally, there’s air pollution. We pollute the air when we burn wood and fossil fuels. As we burn these substances, pollutants get released into the air, and sunlight reacts with these pollutants to create smog: a combination of smoke and fog that makes it difficult for organisms to breath and survive. This also kills off all organisms, which is detrimental to ecosystems as well.

So, the real question is, what can you do to stop this? How can you, a student, help out? You’ve probably heard of the three R’s before: reduce, reuse, and recycle, and these are definite ways to reduce the amount of pollution you create, no matter how small of a reduction this might be.

The first R stands for reduce. Reduce the amount of trash you produce and the amount of energy you consume. Reduce the amount of water and electricity you use, and the amount of paper you waste. Maybe use solar panels instead, which would reduce the amount of fossil fuels burned. The more you reduce your consumption of resources and energy, the better of an impact you will have on the environment.

The second R stands for reuse. Buy products that are reusable, which means you can use them more than once. Given a choice between a metal and plastic water bottle, choose the metal one, because it will last you years, compared with a plastic bottle that will last you minutes. Overall, avoid disposable items, so that you can produce the least amount of trash you can.

Finally, the last R stands for recycle. Now, when reusing and reducing are not options for you, your last resort should be recycling. Recycling items allows them to be used for another purpose in the future. When you dump a plastic water bottle into the recycling bin, the bin will be taken to a facility, which could turn it into loads of different things, including pens and more! However, keep in mind that only 9% of material that you put in a recycling bin is actually recycled by facilities. You must keep yourself informed about what to recycle and what not to recycle, to make sure that recycling facilities will actually recycle your material.

These simple, everyday actions, if performed by everyone, can go a really really long way. While scientists come up with renewable energy sources, while environmentalists find ways for humans to have less of a harmful impact on the environment, it is up to all of us to start cutting down on our bad habits, and help the environment.

Congratulations, you have just finished all of these lessons! You’ve learned a ton about space, the Earth, systems within the Earth, and finally ecosystems. I hope you enjoyed all of these lessons, and I urge you to use this knowledge for a good cause. Thank you!