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Chapter 16 Interactions of Living Things

Preview

Section 1 Everything is Connected

Section 2 Living Things Need Energy

Section 3 Types of Interactions


Concept Map


Section 1 Everything is ConnectedChapter 16

Bellringer

Brainstorm a list of things that you might find in a pond ecosystem.

Select an organism from your list. Then, identify two living things and two nonliving things in the ecosystem that help that organism survive.

Write your answers in your Science Journal.



What You Will Learn

• Biotic factors are the effects of living organisms on each other and on the environment.

• Abiotic factors are the nonliving parts of the environment.

• Ecosystems are made up of organisms and the abiotic factors of the environment.



Studying the Web of Life

• In the web of life, energy and other resources flow between organisms and their environment.

• Ecology is the study of the interactions of organisms with each other and with their environment.

• An organism’s environment is made up of all of the factors that affect the organism.



Studying the Web of Life, continued

• The nonliving factors, such as water, soil, light, and temperature, make up the abiotic factors of the environment.

• The interactions between organisms in an area, such as competition, make up the biotic factors of the environment.




• The environment can be arranged into six levels.

• Biosphere• Biome• Ecosystem• Community• Population• Individual


Chapter 16 Section 1 Everything is Connected





Populations

• Each plant and animal is part of a population.

• A population is a group of individuals of the same species that live together.

• Individuals in a population often compete with each other for food, shelter, and mates.




Communities

• A community is made up of all of the populations of organisms that live and interact in an area.

• The populations in a community depend on each other for many things, such as shelter and food.

• For example, an animal obtains energy, nutrients, and some water by eating other organisms.




Ecosystems

• An ecosystem is made up of a community of organisms and their abiotic environment.

• In an ecosystem, energy and other resources flow between organisms and their physical environment.




• For example, the river that empties into a salt marsh ecosystem, carries nutrients such as nitrogen.

• The cordgrass will grow more quickly because of the extra source of nutrients.


Chapter 16 Section 1 Everything is Connected





Biomes

• A biome is made up of many ecosystems.

• A biome is an area where the climate typically determines the plant community.

• For example, a typical desert biome receives little rainfall, is hot during the day, and cold at night.




• Desert plants and animals are suited to these climate conditions.

• Some of these desert organisms would not survive in a biome that received snow, or one that received ample rain.

• Similar biomes are found in different parts of the world where the climate is similar.




The Biosphere

• The biosphere is the part of Earth where life exists.

• It extends from the deepest parts of the oceans and Earth’s crust, to high in the air where spores drift.

• Scientists study the biosphere to learn how organisms interact with the abiotic environment.


Section 2 Living Things Need EnergyChapter 16

Bellringer

Do you think the flowering plant Indian pipe is a producer or a consumer?

Where does it get the energy it needs to survive?



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What You Will Learn

• Producers, consumers, and decomposers have specific functions in an ecosystem.

• Energy flows from one organism to another in food chains. Many food chains make up a food web.

• The availability of living and nonliving resources affects all organisms.



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The Energy Connection

• Organisms in every community can be divided into three groups: producers, consumers, and decomposers.

• Organisms that change the energy in sunlight into chemical energy or food are called producers.

• Producers convert sunlight into food through the process of photosynthesis.



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The Energy Connection, continued

• Most producers are green plants, but algae and some bacteria are also producers.

• Grasses are the main producers in a prairie ecosystem.

• Cordgrass and algae in a salt marsh are also producers.



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• Consumers must eat other organisms to obtain energy and nutrients.

• A consumer that eats only plants is called an herbivore.

• A consumer that eats other animals is called a carnivore.



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• A consumer that eats both plants and animals is called an omnivore.

• Scavengers are omnivores that eat dead animals and plants.



Interactions of Living Things

Comparing Consumers and Producers

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• Organisms that get energy and nutrients by breaking down dead organisms are called decomposers.

• Bacteria and fungi are decomposers.

• Decomposers produce simple materials, such as carbon dioxide and water, that can be used by other organisms.



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Food Chains

• A food chain is a diagram that shows how energy and nutrients are transferred from one organism to another.

• Producers, such as plants, form the base of the food chain.



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• Herbivores, such as prairie dogs, are also called primary consumers because they are the first consumers in the food chain.

• Organisms, such as coyotes, that eat primary consumers are called secondary consumers.

• Organisms that eat secondary consumers are called tertiary consumers.



Chapter 16Section 2 Living Things Need Energy



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Food Webs

• A food web is a diagram that shows the feeding relationships between organisms in an ecosystem.

• The energy and nutrient connections in nature are more accurately shown by a food web than by a food chain.



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• Energy moves from one organism to another in one direction in a food web.

• Each organism uses energy for its life processes.

• During these processes, some energy is lost to the environment as heat.



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• Any energy not immediately used by an organism is stored in its cells.

• Only the energy stored in an organism’s cells can be used by the next consumer.



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Energy Pyramids

• Only a small part of the energy an organism obtains is transferred to the next consumer in a food chain.

• Thus, more organisms have to be at the base of a food chain than at the top of a food chain.



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• The amount of energy at each level of a food chain can be seen in an energy pyramid.

• An energy pyramid is a diagram that shows an ecosystem’s loss of energy.

• Only about 10% of the energy in each level of the energy pyramid is transferred to the next level of the pyramid.



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Wolves and the Energy Pyramid

• Even a single species can be very important to the flow of energy in an environment.

• Gray wolves are consumers that control the populations of many other animals.

• Wolves are predators that belong at the top of the energy pyramid.



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Wolves and the Energy Pyramid, continued

• As the wilderness of the United States was settled, gray wolves were nearly wiped out.

• Without wolves, elk populations were no longer controlled, so these populations grew.

• The overpopulation of elk in some areas led to overgrazing.



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• Overgrazing left too little grass to support elk and other herbivores.

• The decline in grass led to a decline in herbivores, which led to a decline in predators in the area.

• Soon, almost all of the species in the area were affected by the loss of the gray wolf.




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• Gray wolves were reintroduced into Yellowstone National Park in 1995.

• As the wolves become established, they kill old, injured, and diseased elk.

• The smaller elk population is allowing more plants to grow.




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• The numbers of herbivores, such as snowshoe hares, and the carnivores that eat them, such as fox, are increasing.

• The reintroduction of wolves appears to be balancing the Yellowstone ecosystem.

• However, area ranchers worry about wolves eating their livestock.




Section 3 Types of InteractionsChapter 16

Bellringer

Create a list of predators that are also prey.




What You Will Learn

• Limiting factors determine the carrying capacity of an environment.

• Competition occurs when two or more organisms try to use the same resource.



What You Will Learn, continued

• Prey have unique characteristics to avoid predation.

• Mutualism, commensalism, and parasitism are three kinds of symbiotic relationships that exist between organisms.



Interactions with the Environment

Limiting Factors

• Populations cannot grow without limits, because the environment contains a limited amount of food, water, living space, and other resources.

• A resource that is so scarce that it limits the size of a population is called a limiting factor.



Interactions with the Environment, continued

Carrying Capacity

• The largest population that an environment can support is known as the carrying capacity.

• When a population grows larger than the carrying capacity, limiting factors in the environment cause individuals to die or leave.



• As individuals die or leave, the population size decreases.

• During a rainy season, plants may produce a large crop of seeds and leaves.

• This abundance of food may cause an herbivore population to grow.




• If rainfall decreases the following year, there won’t be enough food for the herbivore population.

• The population has become larger than the carrying capacity.

• Lack of food or other limiting factors will cause the population to decrease.




Interactions Among Organisms

• The three main relationships through which species affect each other are:

• competitive relationships • predator and prey relationships • symbiotic relationships.



Competition

• Competition happens when two or more individuals or populations try to use the same resource.

• Resources such as food, water, shelter, or sunlight may be in limited supply in the environment.

• When one individual or population uses more of a resource, less is available to other organisms.



Competition, continued

• Competition can happen between individuals within a population.

• Elk in Yellowstone National Park compete for the same food plants in the park.

• Competition is especially high in the cold winter, when fewer plants are available.



Competition, continued

• Competition can reduce the size of a population.

• Competition can also happen between populations.

• Different plant species compete with each other for sunlight and space in a forest.



Predators and Prey

• Many interactions between species consist of one organism eating another to obtain energy and nutrients.

• The organism that is eaten is called prey.

• The organism that eats the prey is called the predator.



Predators and Prey, continued

Predator Adaptations

• Predators have a variety of methods for catching prey.

• Some, like the cheetah, run very quickly.

• Others hide and ambush their prey.




Prey Adaptations

• Prey have a variety of methods to keep from being eaten.

• Many animals run away from predators.

• Some prey live in large groups, to increase their ability to spot predators.




• Fish swim in groups called schools. Antelopes and buffalo stay in herds.

• Some prey are poisonous, and advertise their poison with bright colors to warn predators.

• Other prey blend in to their background to avoid being seen




Camouflage• Blending in with the background is called camouflage.

• Fur color often matches the color of the soil or vegetation where an animal lives.

• Many animals mimic twigs, leaves, stones, bark, or other materials in the environment in order to blend in and stay alive.




Defensive Chemicals

• Some animals, like a skunk, spray predators with irritating chemicals.

• Bees, ants, and wasps inject acid into their attackers.

• Some animals have deadly toxins in their skin.




Warning Coloration

• Animals that have a chemical defense often advertise this defense with warning colors.

• The most common warning colors are black, white, and bright shades of yellow, orange, and red.



Symbiosis

• Symbiosis is a close, long-term association between two or more species.

• The individuals in a symbiotic relationship can benefit from, be unaffected by, or be harmed by the relationship.

• Symbiotic relationships include mutualism, commensalism, and parasitism.



Symbiosis, continued

Mutualism

• A symbiotic relationship in which both organisms benefit is called mutualism.

• Mutualism occurs between bees and flowers.

• Bees gain food (nectar) from their interactions with flowers. Flowers receive the pollen needed for reproduction from the bee.




Commensalism

• A symbiotic relationship in which one organism benefits and the other is unaffected is called commensalism.

• One example of commensalism is the relationship between sharks and smaller fish called remoras.




• Remoras attach to sharks and feed on scraps of food left by sharks.

• The remoras benefit from the relationship, while sharks are unaffected.




Parasitism

• A symbiotic relationship in which one organism benefits while the other is harmed is called parasitism.

• The organism that benefits from this relationship is called the parasite.




• The organism that is harmed is called the host.

• The parasite gets nourishment from its host, which weakens the host.

• Sometimes, the host dies and the parasite must find a new host.


Interactions of Living Things

Symbiosis

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Chapter 16 Interactions of Living Things

Use the terms below to complete the concept map on the next slide.

carnivores

sunlight

biosphere

ecosystem

consumers

environment

communities

herbivores

populations

Concept Map


Interactions of Living ThingsChapter 16

Concept Map

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