Ecology: the study of interactions between living things and their environment
Part 1: Getting Energy
Organisms have to get energy from outside of their body in order to survive. Producers, like plants and algae, make their own food by absorbing energy from the sun. Any organism that can't make its own food using a non-living source has to get energy from other organisms, and are called consumers. There are lots of different types of consumers. Herbivores eat plants to get energy, and are found anywhere that plants are found. Cows, deer, squirrels, tomato bugs, and many tiny animals that eat the algae in the ocean are all herbivores. Carnivores are meat eaters, like T-rex, sharks, lions, praying mantis insects, and vultures are all carnivores. Carnivores can get their meat by killing it (predators, like lions and sharks, kill prey, like antelope or fish) or by finding it (scavengers, like crabs and vultures). Some organisms eat both plant and animal material, and are called omnivores ("omni" = all, and "vore" = to eat). Humans, birds, raccoons, and bears are all omnivores. Organisms that consume dead and decaying material and turn it into broken down minerals and nutrients are called decomposers. Fungi (mushrooms, molds, etc.) are almost all decomposers, and so are earthworms, which consume dead plant material and turn it into soil.
Organisms have to get energy from outside of their body in order to survive. Producers, like plants and algae, make their own food by absorbing energy from the sun. Any organism that can't make its own food using a non-living source has to get energy from other organisms, and are called consumers. There are lots of different types of consumers. Herbivores eat plants to get energy, and are found anywhere that plants are found. Cows, deer, squirrels, tomato bugs, and many tiny animals that eat the algae in the ocean are all herbivores. Carnivores are meat eaters, like T-rex, sharks, lions, praying mantis insects, and vultures are all carnivores. Carnivores can get their meat by killing it (predators, like lions and sharks, kill prey, like antelope or fish) or by finding it (scavengers, like crabs and vultures). Some organisms eat both plant and animal material, and are called omnivores ("omni" = all, and "vore" = to eat). Humans, birds, raccoons, and bears are all omnivores. Organisms that consume dead and decaying material and turn it into broken down minerals and nutrients are called decomposers. Fungi (mushrooms, molds, etc.) are almost all decomposers, and so are earthworms, which consume dead plant material and turn it into soil.
An unusual encounter...
Part 2: Living Together
Organisms live around other organisms, even in the most harsh environments, like Antartica or in hot geyser pools in Yellowstone Park. We have seen that organisms rely on other organisms for food. What happens when there isn't enough food for all the things that need it? Do organisms ever help each other? How do living things survive the difficulties of nature?
Organisms live around other organisms, even in the most harsh environments, like Antartica or in hot geyser pools in Yellowstone Park. We have seen that organisms rely on other organisms for food. What happens when there isn't enough food for all the things that need it? Do organisms ever help each other? How do living things survive the difficulties of nature?
What are some other ways, other than eating each other, that organisms interact?
What organisms are competing for resources?
Organisms interact with each other within their populations (same species in an area: herd of bison, flock of penguins, etc.) and within their communities (all the species in one area: coral reef community = different kinds of fish, coral, sponges, anemones, algae, etc.).
Competition is when organisms need something, and there isn't enough to go around. Animals can compete for food, shelter, and mates (among other things). Plants can compete for growing space in the soil, access to sunlight or water, or for pollinators.
Cooperation is when organisms (usually of the same species) help each other. Buffalo in a herd help protect each other. Wolves in a pack help hunt together. A hive of bees work together in almost all ways (and are very complex societies, along with termites and ants!)
Watch this video and try to identify the examples of competition and cooperation. (Don't worry - it has a happy ending!)
When organisms of different species have a long-term relationship with another species, this is called symbiosis. There are three kinds of symbiotic relationships: mutualism (both species are helped: ex. dogs protect humans, and we feed dogs - video), commensalism (one species is helped, and the other doesn't care or notice: ex. humans and our eyebrow mites that we don't even know we have living in our eyebrows - video), and parasitism (the parasite is helped, and the host is harmed: ex. tick and dog - video). Sometimes organisms have relationships that pop up between individuals, but these are not common between the species and are therefore not symbiosis. (See this video for an example for an interaction that is not a long-term relationship.)
Competition is when organisms need something, and there isn't enough to go around. Animals can compete for food, shelter, and mates (among other things). Plants can compete for growing space in the soil, access to sunlight or water, or for pollinators.
Cooperation is when organisms (usually of the same species) help each other. Buffalo in a herd help protect each other. Wolves in a pack help hunt together. A hive of bees work together in almost all ways (and are very complex societies, along with termites and ants!)
Watch this video and try to identify the examples of competition and cooperation. (Don't worry - it has a happy ending!)
When organisms of different species have a long-term relationship with another species, this is called symbiosis. There are three kinds of symbiotic relationships: mutualism (both species are helped: ex. dogs protect humans, and we feed dogs - video), commensalism (one species is helped, and the other doesn't care or notice: ex. humans and our eyebrow mites that we don't even know we have living in our eyebrows - video), and parasitism (the parasite is helped, and the host is harmed: ex. tick and dog - video). Sometimes organisms have relationships that pop up between individuals, but these are not common between the species and are therefore not symbiosis. (See this video for an example for an interaction that is not a long-term relationship.)
Try out this simulation!
Use a 5-minute pass to try out this gizmo on estimating population size. This is a task that biologists in the field have to do all the time, and it's not easy! However, it's very important to keep track of how many organisms are in many different populations, especially those that are endangered species!
Part 3: How are organisms adapted to surviving their environment?
An artic fox is adapted for cold areas.
Abiotic factors are non-living things in the environment that affect organisms and their survival. Examples are weather, salinity of water (in oceans or bays), natural disasters (earthquakes or forest fires), landscape (steep mountains vs. flat land), soil type (sandy or rocky), etc.
The ecosystem that an organism lives includes all the abiotic factors PLUS the entire community of other organisms. Ecosystems can be huge, like coral reefs or forests, or can be tiny, like a fishbowl or your bellybutton (lots of bacteria call this environment "home!")
Organisms have to be adapted to survive all of the pressures that they face in their ecosystem. They have to be able to get food, avoid predators, out-compete other organisms, and survive harsh climate. Adaptations can be either physical (the artic fox's white fur) or behavioral (a goose flies south in the winter). An organism's niche is the overall way that an organism survives - all of its behaviors and physical adaptations that keep it alive in its ecosystem. The goal of having a good niche is to minimize competition with other organisms for scarce resources.
Example: A rabbit's niche is that it is an herbivore that eats all kinds of plants; it burrows underground; it is fast to escape predators; it reproduces often; it has fur that helps it stay camouflaged. It does not compete with squirrels, because even though they are similar in many ways, squirrels nest in trees and eat different types of plant material, like seeds and nuts. The squirrel has a different niche.
SLIDESHOW BELOW SHOWS DIFFERENT ORGANISMS - USE IMAGES TO HELP ANSWER THE SURVEY QUESTIONS.
The ecosystem that an organism lives includes all the abiotic factors PLUS the entire community of other organisms. Ecosystems can be huge, like coral reefs or forests, or can be tiny, like a fishbowl or your bellybutton (lots of bacteria call this environment "home!")
Organisms have to be adapted to survive all of the pressures that they face in their ecosystem. They have to be able to get food, avoid predators, out-compete other organisms, and survive harsh climate. Adaptations can be either physical (the artic fox's white fur) or behavioral (a goose flies south in the winter). An organism's niche is the overall way that an organism survives - all of its behaviors and physical adaptations that keep it alive in its ecosystem. The goal of having a good niche is to minimize competition with other organisms for scarce resources.
Example: A rabbit's niche is that it is an herbivore that eats all kinds of plants; it burrows underground; it is fast to escape predators; it reproduces often; it has fur that helps it stay camouflaged. It does not compete with squirrels, because even though they are similar in many ways, squirrels nest in trees and eat different types of plant material, like seeds and nuts. The squirrel has a different niche.
SLIDESHOW BELOW SHOWS DIFFERENT ORGANISMS - USE IMAGES TO HELP ANSWER THE SURVEY QUESTIONS.
Part 4: Food chains and food webs
Food chains show how energy is passed from one organism to another. The arrows show the flow of energy (ex. the owl gets energy from the rabbit) and does NOT show the action of eating. Food chains are simple examples of what might consume what. See the examples below, and try putting together your own food chain here.
While food chains give examples of what things eat what, they do not show the complexity of interactions within an ecosystem. A food web shows many of the different food sources for organisms in an ecosystem, and also show how interconnected everything is. If one thing is affected in an area, it will affect many other organisms. A food web can help us predict how changes can ripple through an ecosystem.
Part 5: Flow of energy through an ecosystem
Producers are the beginning of the food web because they capture the energy from a non-living source (mostly the sun, but some bacteria use the heat of the earth or chemicals) and put this energy into a form that living things can use. There is a limited amount of energy that is captured by these producers, and the plants use some of this energy themselves to grow and live their lives. When an herbivore (first level consumer) eats these producers, it gets the energy that is stored in the body of the plant. Then what happens to the stored energy? Does the herbivore use a lot of it? Yes! Does the herbivore lose some of it through undigested food (poop)? Yes! Does the herbivore store some of it in fat and muscle? YES! This last bit of energy, that originally came from the producer, is what a carnivore gets when it eats the herbivore. For example, when a lion eats an antelope, it only gets a small portion of the energy that the antelope originally got from the grass that it ate.
Because a lot of the energy is used or lost at each level of consumer, the amount of AVAILABLE energy decreases by quite a bit as it goes up the food chain. It decreases by 90% - so only 10% of the energy consumed by the herbivores gets passed to the carnivores! This means that higher level consumers (like the carnivores), have less energy available to them than the lower level consumers. This loss of energy is shown in an energy pyramid (see example to the left.)
In this example, does it mean that a grasshopper has more energy than a shrew? Should the owl eat the grasshopper instead? NO!! The energy pyramid shows the amount of energy available at each level, not in each organism. There are lots more grasshoppers in a field than there are shrews, so the total amount of energy they store is larger.
In this example, does it mean that a grasshopper has more energy than a shrew? Should the owl eat the grasshopper instead? NO!! The energy pyramid shows the amount of energy available at each level, not in each organism. There are lots more grasshoppers in a field than there are shrews, so the total amount of energy they store is larger.
Try out this simulation!
Use a 5-minute pass to try out this gizmo to see how changing populations of organisms within the food chain affects other organisms. What are the short-term effects of changes in populations, and what are the long-term effects? What does it mean to be measuring the "balance" in the ecosystem?