A Vocabulary of Ecology

• There are many special words that scientists who study ecology use very often.

• Do you remember some of these words?

• We will talk about some of these words now. Maybe you have heard some of them before. We hope they will be useful for you to remember and learn.

Key Words in Ecology:

• Environment 🌳: This is everything around a living thing. It includes all the living things, rocks, soil, and the weather.

• Ecosystem 🧑‍🤝‍🧑: This is a community of living things and their environment. All of them work together.

• Community 🐒: All the living organisms (plants, animals, and tiny living things) that live in a habitat.

• Habitat 🏡: This is the place where a plant, animal, or tiny living thing (microbe) lives.

• Biodiversity ✨: This is a word that means all the different kinds and varieties of living things in many different habitats.

• Species 🐅: A group of living things that are the same kind.

• Herbivore 🌿: An animal that only eats plants.

• Carnivore 🥩: An animal that only eats other animals.

• Omnivore 🥕🥩: An animal that eats both plants and animals.

• Predator 🦅: An animal that hunts and eats other animals for food.

• Prey 🐇: An animal that is hunted and eaten by a predator.

• Producer 🌻: A living thing (usually a plant) that makes its own food at the start of a food chain.

Exploring Ecosystems

• About 250 years ago, scientists called explorers traveled far away to learn about the world. They cut their way through thick jungles and climbed high mountains.

• They kept track of what they saw and collected things. From their notes, we know a lot more about our world.

• One of these explorers was Alexander von Humboldt (1769–1859), a German explorer. He made many trips. He noticed that as he moved from the north to the south, the number of different living things he saw in a place began to change. He had the idea that different parts of the world have their own special kinds of habitats.

• Nain Singh Rawat (1830–1882) was an Indian explorer who explored the Himalayas. He was known as the 'Roof of the world,' and he explored a very large area in South America.

Science in Context

• Do you know? The Daintree rainforest in Australia is thought to be the oldest rainforest ecosystem on Earth! It has been around for about 139 million years! 😮

Figure 7.2 Ecosystems are more diverse in greener, less urban environments.

• In a city, the street is not a natural place. The non-living parts are the buildings, the sidewalk, the cars, and the exhaust fumes in the air. The non-living parts in the park are the grass, the soil under the grass, and the weather.

• All these non-living things react with the living parts of the ecosystem.

• Ecosystems in a city are greener, like parks, or in the country are better for many different kinds of living things than very busy city areas.

The Ecosystem You Live In

• An ecosystem is a way to describe how the living things (plants, animals, and tiny organisms) and the non-living things (like the rocks, soil, and weather) in a certain place work together and affect each other.

• You are a living part of an ecosystem.

• Look around and think about what the weather is like, what the soil is like, and what living things are in that place.

• Most ecosystems have more parts than you may think. If you move to a park or the countryside, you will see many more plants, birds, insects, and other animals, like small mammals and snails or slugs.

• Even a city street is part of an ecosystem.

Do You Remember?

• What is a food chain? A food chain shows how living things eat one another.

• Give an example of a food chain. A simple example is: Grass $\rightarrow$ gazelle $\rightarrow$ lion. (The grass is eaten by the gazelle, and the gazelle is eaten by the lion).

• What do these terms mean: producer, consumer, herbivore, omnivore, carnivore, predator and prey?

  • Producer: A living thing (like a plant) that makes its own food.

  • Consumer: An animal that eats other animals or plants.

  • Herbivore: An animal that only eats plants.

  • Omnivore: An animal that eats both plants and animals.

  • Carnivore: An animal that only eats other animals.

  • Predator: An animal that hunts and eats other animals.

  • Prey: An animal that is hunted and eaten by a predator.

• What is a habitat? The place where a plant or animal lives.

• What does the difference between a food chain and a food web mean?

  • A food chain is a simple line showing who eats who.

  • A food web is many food chains linked together to show how food and energy move through a whole community.

• What is the difference between a food chain and a food web? (This is the same question as above, answered by the definitions).

• Why are micro-organisms important in a habitat? Explain your answer. Microorganisms (tiny living things like bacteria and fungi) help break down dead plants and animals into food (nutrients) for the soil. This helps new plants grow.

Three Examples of Ecosystems

• An ecosystem is a community of plants, animals, and tiny living things that live in a certain place.

The Rainforest Ecosystem 🌳

• Rainforests are found in areas around the middle of the planet, as Figure 7.8 shows.

• They are found in parts of Central and South America, Africa, Australia, and Asia.

Challenge Yourself (Question 6)

• Which area of rainforest is closest to where you live? Try to find out more about it in the Challenge yourself on page 70. (This question asks the student to check the map and research the nearest rainforest).

Food Chain and Web Words

• Consumer 🍽️: An animal that eats plants or other animals (it may be a plant-eater or a meat-eater).

  • Primary consumer (First consumer): An animal that eats plants (this animal is a herbivore).

  • Secondary consumer (Second consumer): An animal that eats the primary consumer (this animal may be a carnivore or an omnivore).

  • Tertiary consumer (Third consumer): An animal that eats the secondary consumer (this animal may be a carnivore or an omnivore).

  • Quaternary consumer (Fourth consumer): An animal that eats the tertiary consumer (this animal may be a carnivore or an omnivore).

• Top carnivore 👑: The animal at the very end of the food chain.

• Food chain ⛓️: A simple drawing or list that shows the way some living things eat others. A food chain starts with a producer and is followed by one or more consumers.

  • Example: Grass $\rightarrow$ gazelle $\rightarrow$ lion.

• Food web 🕸️: A picture or list that connects many food chains together. It shows how food and energy move through a whole community (often a diagram).

• Keystone species 🔑: A plant or animal that is very important and helps other living things in a habitat stay alive. If this species is gone, it would reduce the number of plants and animals in the habitat.

The Four Layers of a Rainforest Ecosystem

Rainforests are very tall and can be split into four layers:

• Emergent layer: 40 to 50 meters high.

• Canopy layer: 30 meters high.

• Understory layer: 10 meters high.

• Forest floor: 0 meters high.

Forest Floor (The bottom layer, 0m high)

• The forest floor is the ground layer.

• The plant parts and the soil on the forest floor make up the home for all the living things in the rainforest.

• In the soil, tiny living things called microbes break down dead plants and animals very quickly because the forest floor is warm and wet. This creates food (nutrients) that plants take up with water through their roots.

• The forest floor has many fungi, decaying (rotting) tree trunks, and dead leaves. They grow to make new things and help living things reproduce.

• Animals on the floor include mammals like the leopard, who rests here and hunts other animals, and snakes, who also look for prey. Larger animals like the tapir walk here.

• Animals like leeches and worms live in the soil and on the ground. Leeches suck blood and they have suckers at both ends of their body. Worms are invertebrates (animals with no backbones) that are in the same group as earthworms.

Understory Layer (About 10m high)

• The understory layer is made up of small trees and bushes.

• Insects often grow up into this layer.

• There are plants called pitcher plants here. These plants are special because they eat insects. They have pitchers (like cups) that are filled with liquid. Insects fall into the liquid and are digested (eaten) by the plant.

Canopy Layer (About 30m high)

• The canopy layer is formed by the branches of the larger trees.

• There is a lot of light here.

• This layer is the home for many animals, such as monkeys, like the langur and macaque, and plants like orchids and ferns that grow on the trees.

Emergent Layer (About 40–50m high)

• The emergent layer is made by the tallest trees.

• Eagles and hawks build their nests here and rest on the branches.

• Animals like the gliding frogs use the spaces between the branches to move by gliding, using the skin between their toes (like a small web).

The Desert Ecosystem 🏜️

• A desert is a land area that gets very little rain.

• Deserts are found in the North and South America, Africa, Australia, Asia, and Antarctica.

The Three Main Habitats in a Hot Desert

• There are three main places where things live in a hot desert: sand dunes, rocky and thin soil, and oases.

1. Sand Dunes 🏖️:

   • These are big piles of moving sand that are called dunes.

   • The dunes change their shape and position as the wind blows them.

   • If it rains, seeds in the sand grow and make new plants. These plants live for short times.

   • Lizards and birds often live here and bury themselves in the sand to hide and keep cool.

2. Rocky and Thin Soil 🌵:

   • Where there are rocks and thin soil, larger, permanent (long-lasting) plants can grow.

   • Plants like the cactus or the yucca live here.

   • These plants provide a home for many animals, such as birds called cactus wrens or small mammals like squirrels.

3. Oases 🌴:

   • An oasis is an area of a small ecosystem in a larger desert ecosystem.

   • There is water deep under the ground in the dunes, which comes up to the surface to make a well or a pool of water.

   • The water is important for birds and insects.

   • Plants grow around an oasis, and they are food for animals like grasshoppers and butterflies, which are eaten by lizards and birds.

Challenge Yourself (Question 7)

• Which area of desert is closest to where you live? Try to find out more about it in the Challenge yourself on page 71. (This question asks the student to check the map and research the nearest desert).

The Ecosystems of the Oceans and Seas 🌊

• The oceans and seas give a very important source of water for the whole planet. They also provide water for large animals.

The Oceans and Seas of the World:

• Southern Ocean

• Atlantic Ocean

• Pacific Ocean

• Indian Ocean

• Arctic Ocean

• Seas shown on the map include: Weddell Sea, Scotia Sea, Caribbean Sea, Philippine Sea, Arabian Sea, Red Sea, Mediterranean Sea, Black Sea, Caspian Sea, Yellow Sea, Sea of Japan, Bering Sea, Sea of Okhotsk, East Siberian Sea, Laptev Sea, Barents Sea, White Sea, North Sea, Baltic Sea, Norwegian Sea, Greenland Sea, Labrador Sea, Tasman Sea, Coral Sea, Arafura Sea, Celebes Sea, South China Sea, East China Sea, North Pacific, South Pacific, North Atlantic, South Atlantic, North Arctic, South Arctic, Beaufort Sea.

The Ocean Ecosystem

• The ecosystem of the ocean is divided up into different parts called zones.

• The two main zones are the rocky shore and the sandy shore.

• The intertidal zone is the place where the tide moves up and down the sea-shore. This area is under sea-water for a few hours every day.

• This zone has many different habitats.

Challenge Yourself (Question 8)

• What is the nearest sea or ocean to where you live? Try to find out more about it in the Challenge yourself on page 73. (This question asks the student to check the map and research the nearest sea or ocean).

Zones of the Ocean

The open sea is further away from the coast and is divided into three zones based on how much sunlight reaches them:

1. Sunlit Zone 🌞:

   • This is the top layer where there is enough sunlight for tiny plants (called microscopic plankton) to make food.

   • These tiny plants float in the water and are the food for small animals and tiny living things like sea urchins and jellyfish.

   • The coastal zone is the part of the open sea nearest to the shore. It has deep water and big amounts of seaweed and tides.

2. Twilight Zone 🌗:

   • This is the middle layer, where there is not enough light for plants to make food.

   • Some animals live here, but they eat tiny things that float down from the sunlit zone.

   • Other animals here are carnivores (meat-eaters) and may eat other animals that sink down from the sunlit zone.

   • Other animals live on the dead bodies of other creatures that sink to the bottom.

   • Some animals have organs (special parts) that give off light to help them see and talk to other animals.

3. Dark Zone ⚫:

   • This is the deepest layer, where there is no light at all.

   • There is no light in the dark zone.

   • The animals here feed on pieces of dead bodies that sink down from higher in the water.

   • Those pieces that remain uneaten are broken down by decomposers on the ocean floor.

   • There are decomposers on all the surfaces in these zones, from the sea-shore to the ocean floor, which release nutrients back into the water as they feed.

Modelling an Ecosystem

• From the study of many ecosystems, a simple model has been constructed that can help you understand the interactions that take place.

• The ecosystem can be quite small, such as a pond, or as large as a lake or a forest.

• You will have already studied all the relationships shown in Figure 7.20 in your science course, except for the arrow from producers to oxygen and the arrow from carbon dioxide to producers. You will investigate this relationship next year.

Questions from Figure 7.20 (Modelling an Ecosystem)

• 9. What colour of arrow shows the movement of carbon dioxide? The blue arrow shows the movement of carbon dioxide.

• 10. What colour of arrow shows nutrients through the decomposition of the dead bodies? The purple arrow shows nutrients through the decomposition of the dead bodies.

• 11. What colour of arrow shows the movement of soil to the plants? (This is not shown directly on the diagram, but the question is retained).

• 12. What colour of arrow shows the living things alive? (This is not shown directly on the diagram, but the question is retained).

• 13. What do living things do when using things that is produced from a gas part of the air to allow the body to breathe and stay alive? Living things take in a variety of substances to stay alive, such as oxygen to release energy from stored food for life processes, and nutrients such as proteins to build and repair bodies.

• 14. What do decomposers get their food from? Decomposers get their food from dead bodies and waste.

Bioaccumulation

• Living things can also take in toxic substances (also known as toxins) which are poisons.

• These do not take part in chemical reactions to keep the body alive or to build and repair it.

Science Extra (Bioaccumulation)

• Animals with a non-lethal level of toxins in their body may still move around in their habitat and be eaten by a predator.

• As the predator moves through the habitat, feeding on the toxic animals, its own level of body toxins rises higher than the levels of its prey. This increase in toxins as you go up the food chain is called biomagnification.

Science in Context (A poison in the food chain)

• In 1935, a Swiss chemist called Paul Müller (1899–1965) set up a research program to find and create substances that would kill insects but would not harm plants or other animals.

• Müller found a substance called dichlorodiphenyltrichloroethane (DDT), which was first made in 1874.

• DDT smelled good and seemed to meet all the requirements, and soon it was being used worldwide.

• The discovery of bioaccumulation and biomagnification of toxins in the food chain was made by careful ecological investigations carried out in the mid-20th century.

Pollution in an Ecosystem

• Pollution can lead to bioaccumulation.

• Some toxins can be broken down by chemical reactions in the body and made into harmless substances which are released from the body.

• Other toxins may be released from the body with solid wastes in the process of egestion.

• If a toxin is not broken down or egested, it becomes concentrated in the body by a process of bioaccumulation.

• When this happens, the toxins can damage the life processes taking place in cells, and as they build up further, the toxins eventually stop the life processes altogether and the plant or animal dies.

• Some of the most common toxins are those used in pesticides. A pesticide is a substance (spray or powder) that is used to kill organisms which compete with our crops and reduce the production of food.

• Examples of pesticides include herbicides (which kill weeds), fungicides (which kill fungi) and insecticides (which kill insects).

• If these are not used carefully, they spill over from the crop fields into the surrounding habitats and are taken up by the plants and animals living there.

Did You Know?

• The biosphere is the highest part of the planet where living things are found, to the deepest part of the oceans and the rocks, where microbes and spores (seeds and tiny living things) may be found.

The Effects of Pollution and Waste

• A substance called DDT did not break down in the environment but was taken into living tissue and stayed there.

• As the plankton in the water were eaten by the small fish, the DDT was taken in by the small fish, which the DDT did not break down.

• The small fish were then eaten by the larger fish, in which the DDT formed higher concentrations (amounts).

• The grebes (a type of bird) ate the large fish and with every meal increased the amount of DDT in their bodies until it killed them.

• In the UK, the peregrine falcon is a top carnivore in a food chain in marshland habitats. Because it ate other birds outside of the breeding season, the concentration of DDT in their bodies eventually caused them to lay eggs with weak shells and the embryos died.

• Pollution can also hurt the relationship between organisms in an ecosystem.

Questions (from Figure 7.23)

• 14. Construct the food chain investigated in Clear Lake. Microscopic plankton $\rightarrow$ small fish $\rightarrow$ large fish $\rightarrow$ grebes.

• 15. Why did the grebes die? The concentration of DDT in the grebes' bodies became too high and killed them.

• 16. How are the lives of people who live near polluted rivers, or polluted seas, put at risk? The concentration of mercury poisoning, shown signs of mercury, put the lives of large number of people in a village at risk. Many safe to drink.

• 17. The water flowing through the village had such low levels of mercury, but it was considered dangerous for humans. How could this be? The most harmful pollutants in water are PCBs (polychlorinated biphenyls) and heavy metals such as cadmium, chromium, nickel and lead. In large concentrations these metals can damage many of the organs of the body, and can cause cancers to develop. PCBs are used in making plastics and, along with mercury compounds, end up in the food chain. Organisms at the beginning of the food chain, such as tiny plants, take up the toxins. These are passed up the food chain as each step is taken and are then at the next one in the chain. This leads to organisms at the end of the food chain having large amounts of toxic chemicals in their bodies, which can cause permanent damage or death.

• Careless use of fertilisers allows the green growth of water plants (including grasses and algae) and leads to the overgrowth to drain from the land into rivers and lakes.

• The growth of tiny water plants called algal blooms blocks the sunlight from getting to the plants under them, which stops them from making food.

• When these blooms cover large numbers of tiny plants, the reduction in oxygen levels in the water kills many water animals.

• Phosphates in decomposing bacteria (tiny living things that break things down) take in oxygen from the water.

• This reduction in oxygen levels in the water kills many water animals.

• Detergents also cause an overgrowth in water animals, which can lead to the death of water animals in the same way. * Litter in the form of tins and plastic, can cover up plants and prevent light getting to them, so they die.

• Litter can physically damage organisms in an ecosystem.

Invasive Species

• An invasive species is a species of living thing which enters an ecosystem in which it is not naturally found and causes damage to that ecosystem.

• An early example of the effect of invasive species occurred during the European colonisation of Australia.

• When European rabbits were introduced to Australia, they spread quickly because there were no natural predators (animals that hunt them) to control their numbers.

• They competed with native animals, such as the boodie and the burrowing bettong (small Australian mammals), for food and space. * Introduced animals, like foxes and cats, increased their population rapidly, so foxes preyed on the native Australian mammals.

• The populations of some native mammals, such as the boodie in Australia, are threatened by invasive species.

• The invasion of foxes and cats led to the extinction of over twenty Australian mammal species.

• Domestic cats brought over by the settlers also found some native mammals easy prey, and the invasion of foxes and cats led to the extinction of over twenty native Australian mammals.

• Glass bottles can become traps for small animals like mice. Once they have crawled inside, they cannot grip the smooth walls inside the bottle and climb out.

• Plastic debris can be eaten by a wide range of animals. The plastic can damage the tear-down digestive system, stopping it from working, and the animal dies. * Pampas grass is an example of an invasive plant. It was introduced from its natural habitat in the Andes in South America into gardens in New Zealand.

• As its seeds can travel up to 25 km on the wind, it has spread into surrounding ecosystems where it competes for light and nutrients with the plants that grow there naturally.

End of Chapter Questions

• 1. Name two ecosystems found on land on the Earth. The Rainforest ecosystem and the Desert ecosystem.

• 2. Name four habitats in the ocean ecosystem. Rocky shore, Sandy shore, Sunlit zone, and Twilight zone.

• 3. What is a toxin? A toxin is a poisonous substance that can hurt living things.

• 4. How are toxins harmful to living things in an ecosystem? Toxins can damage the cells of living things and can eventually kill the plant or animal.

• 5. Name two toxins which can damage an ecosystem. DDT and Mercury (or PCBs, Cadmium, Chromium, Nickel, Lead).

• 6. What does 'bioaccumulation' mean? Bioaccumulation is the process where a toxin builds up in the body of a living thing over time.

• 7. What is an invasive species? An invasive species is a living thing that enters a new ecosystem where it is not naturally found and causes harm.

• 8. Give an example of an invasive species. Rabbits, foxes, cats, or Pampas grass.

• 9. How can invasive species damage an ecosystem? You may use one or more examples in your answer.

  • Invasive species compete with native species for food and space (like rabbits competing with native Australian mammals).

  • They can become predators of native animals that are not used to being hunted by them (like foxes and cats eating native Australian mammals). This can cause the native species to die out.