Environmental Science

Characteristics of Living Things

The world is filled with millions of organisms. An organism is a living thing. A mosquito is an organism. An elephant is an organism. Mold is an organism. A palm tree is an organism. You are an organism. All organisms have things in common. Living things have characteristics or traits that make them different from non-living things. All living things share the following traits:

Living Things are made up of cells

Living Things Use Energy

Living Things Grow and Develop

Organisms respond and adapt to their environment

Organisms have a life-span

Organisms reproduce

Needs of Living ThingsAll living things have needs too. All organisms need:

Energy

Air

Food and Water

Living Space

Acceptable Temperature

Living Things and the Environment

Organisms get the things they need from their environment or habitat. Different organisms live in different habitats because their needs are different. A polar bear has very different needs than a desert cactus!

There are two factors within an organisms habitat. Biotic factors are the living things in a habitat such as plants, animals, bacteria, etc. Abiotic factors are the non-living things in an environment such as rocks, sand, air, sunlight, water, soil, temperature etc.

Can you think of some biotic and abiotic factors of your backyard?

EcologyEcology is the study of how living things interact with each other and their environment.

An ecosystem is all the living and non-living things in a particular area.

Within an ecosystem, many different populations of organisms interact and compete for the things they need.

The size of a population of a particular organism can be influenced by many factors. Organisms compete for food, water and living space. When there isn’t enough to go around, the population of a species decreases or goes down. These factors are called limiting factors….they limit populations.

Adapting to the EnvironmentIn order to survive, organisms must adapt or change to survive in

their environment. Only the strongest organisms survive and the ones who cannot adapt may not survive. The process in which only the best suited organisms survive their environment is called natural selection. When organisms make changes in their behavior or physical appearance, this is called adaptation.

Living things may adapt in several different ways. A polar bear grows a thick fur to protect it from the cold. Some animals hibernate during the winter. A walking stick looks just like a stick and is camouflaged with its surroundings. A porcupine has sharp quills to protect it from its enemies and some animals have bright colors to warn predators off. A skunk has a stinky spray!

Competition

When there is a limited amount of food, water or space in the environment, organisms are forced to compete with each other. Competition is a situation where organisms struggle with each other and their environments in order to get what they need to live.

All ecosystems are based on competition. Competition controls the populations within a habitat so that no one population gets too large.

Animals that catch and eat their prey are called predators. The animals the predators eat are the prey.

Q: What would happen if the number of prey in an ecosystem declined?

Q: What would happen if the number of predators in an ecosystem declined?

prey predator

Symbiotic Relationships

Instead of competing with one another, sometimes organisms depend on each other by living together and helping one another.

Symbiosis is a relationship between two organisms in which one or both of the partners benefit.

There are three types of symbiotic relationships: commensalism, mutualism and parasitism.

Mutualism

Mutualism is a relationship in which both organisms benefit.

For example, small birds sometimes “piggyback” on top of hippos in order to get their food. They pick off small insects to eat. The hippo benefits because the insects are removed and the birds benefit because they got a good supper!

Commensalism

Commensalism is a relationship between two organisms in which one member benefits and the other is neither harmed, nor helped.

For example, a bird builds a nest in a tall tree… The tree provides protection to the bird from ground predators. The bird is helped and the tree doesn’t even know the difference!

Parasitism

In the relationship of parasitism, one partner benefits and the other is harmed.

A blood-sucking flea is a great example of a parasite. The flea is the parasite and the unfortunate dog is it’s host. The parasite benefits and the host is harmed.

Energy Flow in Ecosystems

Organisms get energy in different ways. Some organisms get energy directly from the sun, while others must eat plants or animals. Each organism in an ecosystem fills one of three energy “roles”: producer, consumer and decomposer.

The sun is the source of all

energy in an ecosystem! The

energy must be passed from

one organism to another!

Producers

Energy enters an ecosystem as sunlight. Plants absorb that sunlight with their leaves. They combine the energy with water and carbon dioxide to make “food” for themselves. They release oxygen which humans and animals need to survive. The process in which plants use sunlight, water and carbon dioxide to make their own food is called photosynthesis.

Plants are known as producers or autotrophs because they produce or “make” their own food.

ConsumersConsumers, or heterotrophs are organisms that cannot make their own food. They must rely on producers or consumers that eat producers for energy.

Consumers that eat only plants are known as herbivores. A cow is an example of an herbivore.

Consumers that eat animals are known as carnivores. A wolf is a carnivore.

Omnivores are consumers that eat both plants and animals. Most humans are omnivores.

herbivore carnivore omnivore

Decomposers

Decomposers are organisms that get their energy by breaking down waste or dead organisms into nutrients. The nutrients are then recycled back into the environment.

Fungi and bacteria are examples of decomposers. A log on the ground disappears over time, it has decomposed. A dead animal will eventually decompose.

Decomposers are nature’s recyclers!!!

But We Can’t EAT the sun!!??

Q: The sun is the source of energy, but we don’t eat the sun! We need energy to live so how do we get it?

A: We sit down and eat a juicy cheeseburger. Where did the burger come from? Exactly, a nice juicy cow. And what did the cow eat? Grass. Where did the grass get its energy? The sun! Now do you get it?

So, next time when you sit down to eat a cheeseburger, you can say mmmm…that’s good sun!

Food Web

A food web is a way to show how the energy from the sun gets passed around different organisms in the environment.

Energy Pyramid

The energy pyramid shows how energy moves from one level to another. The sun provides energy to the plants, the mice eat the plants and the snake eats the mice. Energy travels from one level to another. A little bit of energy gets used at each level.

The Water Cycle

The water cycle is important to life. Water evaporates from the Earth, condenses in the clouds and then falls back to Earth in the form of rain, sleet, snow or hail (precipitation).

Carbon Dioxide and Oxygen Cycle

Plants take in carbon dioxide and produce oxygen. Animals and humans take in oxygen and release carbon dioxide. Plants and animals need each other for survival.

Nitrogen Cycle

Animals eat plants, that contain nitrogen. The animals produce waste which goes into the ground. Decomposers (bacteria) break down the waste and release nitrogen back into the air and soil. Plants use the nitrogen rich soil and the process begins again.

Biomes of the World

Rainforest

Desert

Grasslands

Deciduous Forest

Boreal Forest and Taiga

TundraBiomes are determined based on their climate-temperature

and precipitation.

RainforestThere are two types of rainforests: temperate rainforest and tropical rainforest

A temperate rainforest has medium to low temperatures, but a lot of precipitation. The northwestern part of the United States has a temperature rainforest.

Tropical rainforests have hot climates and a lot of precipitation. Tropical rainforests are found mostly near the equator and have a huge variety of plants and animals.

There are major tropical rainforests in South America (Amazon Rainforest), middle Africa and in Indonesia.

Deserts

A desert is an area that gets little or no precipitation each year.

A hot desert becomes very cool at night.

Some deserts are cooler and actually get low temperatures.

Organisms that live in the desert must adapt to dry situations in order to survive. A cactus can hold a large amount of water when it rains because it has to conserve it during dry times.

Most desert animals are active at night when it is not so hot.

GrasslandsThere are two kinds of grasslands: prairie grasslands and savanna grasslands.

Prairie grasslands get little rain, not enough for trees to grow. Because of the dry climate, many fires start. North America has a large area that is prairie grasslands.

Animals such as bison, rabbits, prairie dogs, hawks, mice, fox, ferrets, snakes and owls live in the prairie grasslands.

Savanna grasslands receive more rain than prairies and are home to animals such as the elephant, zebra, antelope, giraffe, and rhino. Africa has large areas of savannah grasslands.

Deciduous Forest

Deciduous trees are trees that lose their leaves and grow new ones each year. A deciduous forest is a forest with many deciduous trees.

Deciduous forests have enough rain to support the growth of trees.

The temperatures in deciduous forests are quite different during the seasons of the year, spring, summer, winter and fall.

Animals like skunks, squirrels, chipmunks, birds, deer, fox and bear live in deciduous forests. Many of these animals have to adapt to cold winters or migrate to warmer areas during that time.

Boreal Forests or “Taiga”

A boreal forest is a forest where most of the trees are coniferous. A coniferous tree is a tee that produce cones and needles instead of leaves.

Winters are very cold and summers are mild. There is snow much of the year.

Animals such as beavers, moose, elk, owl, lynx, bear, wolves, squirrels, fox and birds live in boreal forests.

Tundra

The tundra is an extremely dry and cold biome. A tundra is covered with snow most of, if not all of the year. The ground is permanently frozen. This is called permafrost.

Few plants grow on the tundra, mostly grass, moss, shrubs and small trees.

Animals such as caribou, musk ox, foxes, wolves. [polar bear and arctic rabbits live in the tundra. They have to have thick fur to protect them from the cold.

Tundra Biomes:

Aquatic Ecosystems“Aqua” means water. Aquatic ecosystems are water-based habitats.

There are two types of aquatic ecosystems: freshwater and marine (salt water) ecosystems.

Aquatic ecosystems, like land ecosystems depend on sunlight, temperature and oxygen to make life successful. Organisms must adapt to their surroundings in order to survive.

Freshwater Saltwater

Freshwater Ecosystems

There is a lot of water on our Earth, but only a small amount is made up of fresh water. Therefore it is important to protect our fresh water!

Freshwater ecosystems include lakes, ponds, rivers and streams.

Marine EcosystemsAn estuary is found where the fresh water of a river meets the salt water of an ocean.

The Intertidal Zone is the rocky area along the ocean shoreline that experiences the highs and lows of the tides.

The Neritic Zone is the shallow part of the ocean that covers the continental shelf. Sunlight is able to reach through the water so this zone supports a lot of life.

The Open Ocean is made up of the surface zone and the deep zone. Light from the sun can shine through the surface zone, so life is plentiful. The deep zone gets little to no sunlight.

Did you know? Our Earth is sometimes called the “Blue Planet?” Do you know why?

Tide Pools:

Open Ocean

Changes In the Environment

Ecosystems are always changing. Sometimes those changes are quite fast, like in the case of a natural disaster. A natural disaster like a flood, fire, earthquake, mudslide, hurricane or volcanic eruption can instantly change an environment and kill the communities that live there. If this happens, a new community will replace the old community over time. This is called succession. An example of succession is when a field is left untouched for a long time, it may turn into a forest. If a volcano wipes out a forest, it will eventually grow back.

What Else Changes the Environment?

The Greenhouse Effect:

There are gases in the Earths atmosphere that are known as greenhouse gasses. The gases let sunlight pass through and trap some of the sun’s heat so that the Earth stays warm. This is called the greenhouse effect. This is great for plants and animals to live, but too much greenhouse effect is a bad thing.

Worldwide pollution caused by humans is creating more greenhouse gasses. Some scientists believe that this will increase the temperature of the planet, resulting in global warming. This warming may cause glaciers to melt and ocean levels to rise.

Other scientists think that the Earth will become colder because the sun’s rays will be blocked by pollution. Either way, people should be more thoughtful of the Earth because it is our only home!

What Else Changes the Environment?

The Earth is protected by the atmosphere. The atmosphere is the air that surrounds the Earth. It protects us from the sun’s bad rays. Ozone, a gas, absorbs most of the UV rays. Ozone protects people when it is high in the atmosphere, but it can hurt people when it is near the ground. Smog, is a fog-like substance caused by pollution. It contains ozone that can harm people. Bad ozone formed on Earth, rises into the atmosphere and causes good ozone to break down. This thinning of the good ozone layer weakens the part of the atmosphere that protects animals, plants and humans from the sun. Again, humans creating pollution is bad for our planet!

Ozone Depletion

What Harms Our Environment?

Air Pollution: We pollute our air with factory pollution and car exhaust. Organisms, including humans need clean air to survive.

Soil Pollution: We pollute our ground with chemicals, hazardous waste and garbage. These hazardous materials can get into our drinking water and harm us.

Water pollution destroys life in the Earth’s freshwater ecosystems and oceans.

What Else Harms our Environment?

Spraying pesticides and insecticides. It kills the bugs we don’t want, but what does it do to the environment?

Deforestation is the cutting down of many trees and not replacing them. We use wood as a resource, but trees support plant and animal life. We must think about our future before cutting down acres of forests, without making plans to replace them!

What Else Harms Our Environment?

Construction: Expanding the places where humans live harms the natural ecosystems. Life in those ecosystems must move elsewhere and some do not survive.

Waste: People produce so much waste! Humans should be encouraged to follow the three R’s: reduce, reuse, and recycle! Many materials like plastic, glass, metal and paper can be recycled and re-used without causing more harm to our environment.

Extinction

Extinction means the disappearance of a species. This is a natural process and throughout history, many organisms have become extinct, like the dinosaurs. Organisms that are in danger of becoming extinct are known as endangered species. Although extinction happens naturally, humans have a large role in endangering species. Our actions destroy the ecosystems and endanger the organisms that live in them.

Species are more likely to become extinct if:

They are naturally rare

They are sensitive to changes in the environment

They have “picky” food or shelter needs

They have small numbers of offspring

They interfere with people in some way

A Final Thought:

Our world is full of resources that we need in order to survive. We must take care of those resources!

Ecosystems contain many resources. We must make certain not to harm or ruin them.

Plants and animals rely on one another. If one disappears, so does the other. Humans rely on both plants and animals.

Clean air, land and water are our most precious resources. We must do our best to keep them clean!