Living Things in Their Environment
Key question — How do living things occupy their environment and what do they need to live?
- Understand what an environment and a habitat are.
- Identify the essential needs of living things.
- Observe the relationships between living things and elements of their environment.
- Understand that environmental conditions influence the presence of living things.
Part 1: Understanding the Environment of a Living Thing
The environment of a living thing includes everything around it: other living things, water, air, soil, light, temperature, and features of the landscape.
A living thing never lives alone, separated from its surroundings. It occupies a place where it finds what it needs to live. This place can be very large, like a forest, or very small, like beneath a damp stone.
Within an environment, we can distinguish living elements and non-living elements. Living elements are the living organisms present in the environment. Non-living elements are parts of the environment that are not alive, like water, air, rocks, light, or temperature.
| Type of Element | What It Means | Examples |
|---|---|---|
| Living elements | These are the living organisms present in the environment. | Trees, grasses, insects, birds, fungi, bacteria. |
| Non-living elements | These are components of the environment that are not alive. | Air, water, rocks, soil, light, temperature. |
A habitat is a place where a living thing finds the necessary conditions to live, feed, protect itself, and reproduce.
A pond is a habitat for frogs, algae, aquatic insects, and microorganisms. It also contains non-living elements such as water, light, mud, rocks, and dissolved oxygen.
The environment of a living thing includes everything around it. It contains living elements like animals, plants, fungi, and microorganisms, as well as non-living elements like water, air, soil, light, and temperature. A habitat is a place where a living thing finds the necessary conditions to live.
Part 2: The Needs of Living Things
All living things have needs to survive. These needs are not exactly the same for all species, but some are common to many living things.
A vital need is an element or condition essential for a living thing’s survival, such as water, food, oxygen, or an appropriate temperature.
The Needs of Animals
Animals need to eat, breathe, find water, protect themselves, and reproduce. Their habitat must provide the necessary resources.
- Food provides matter and energy.
- Water is essential for the body's functions.
- Oxygen, present in air or dissolved in water, enables breathing.
- Shelter can protect against cold, predators, or bad weather.
- A partner is necessary for sexual reproduction in many animal species.
The Needs of Green Plants
Green plants do not feed like animals. They produce their own matter using light, from water, mineral salts, and carbon dioxide. This process is called photosynthesis.
A green plant is a living organism capable of producing its own matter using light, from water, mineral salts, and carbon dioxide.
| Living Thing | Main Needs | Example |
|---|---|---|
| Terrestrial animal | Food, water, oxygen from air, shelter. | A hedgehog finds insects, water, and shelter under leaves. |
| Aquatic animal | Food, oxygen dissolved in water, suitable aquatic habitat. | A fish lives in water containing oxygen and food. |
| Green plant | Light, water, mineral salts, carbon dioxide. | Grass grows if it receives light, water, and mineral salts. |
| Fungus | Organic matter, moisture, suitable habitat. | A fungus can develop on wet dead leaves. |
A snail is often found in damp places. Its soft body can dry out in too dry an environment. Therefore, humidity is an important condition for its presence.
Living things have vital needs. Animals require food, water, oxygen, and a suitable habitat. Green plants need light, water, minerals, and carbon dioxide to produce their matter. The needs of a living thing partly explain why it lives in certain habitats rather than others.
Part 3: Living Things Are Not Distributed Randomly
When observing an environment, we notice that living things are not present everywhere in the same way. Some live in water, others on soil, under stones, in trees, or in very bright areas.
The distribution of living things refers to how they are present in an environment: the places they occupy and their numbers.
Environmental Conditions Influence the Presence of Living Things
Several conditions explain the presence or absence of living things in a habitat.
- Light affects the growth of green plants.
- Humidity influences the presence of some animals and fungi.
- Temperature can limit the activity of certain living things.
- Soil type can favor some plants.
- Food availability attracts certain animals.
- Shelter availability allows animals to protect themselves.
In a yard, mosses are more common in shaded and damp areas than on a dry, very sunny surface. Therefore, moss distribution depends on environmental conditions.
Comparing Two Zones in the Same Environment
To understand living thing distribution, we can compare two nearby zones. For example, we observe a dry, sunny area and then a damp, shaded area.
| Observed Zone | Environmental Conditions | Possible Living Things |
|---|---|---|
| Sunny wall | Lots of light, warmth, low humidity. | Lichens, small plants resistant to drought. |
| Soil under a hedge | Shade, humidity, dead leaves, shelter. | Earthworms, woodlice, fungi, mosses. |
| Pond | Water, variable light, mud, aquatic plants. | Algae, insect larvae, frogs, aquatic snails. |
This comparison shows that an environment can contain multiple small habitats. Each has specific conditions and can host different living things.
Living things are not randomly distributed in their environment. Their presence depends on environmental conditions such as light, humidity, temperature, soil, food, and available shelter. A single environment can contain several different habitats.
Part 4: Relationships Between Living Things and Their Environment
In an environment, living things relate to non-living elements as well as other living things. These relationships allow them to feed, protect themselves, reproduce, or move.
An ecosystem is the whole formed by a habitat, the living things that occupy it, and the relationships that exist between them and with their environment.
Relationships with Non-living Elements
Living things depend on the non-living parts of their environment. A plant depends on light and water. A fish depends on water and dissolved oxygen. A woodlouse often lives in a damp and dark place.
If a pond dries up, aquatic living things like certain insect larvae or aquatic snails may disappear because they no longer find the conditions necessary for life.
Relationships Between Living Things
Living things can also depend on each other. Some feed on other living things, some use plants as shelter, and others help break down dead matter.
- A caterpillar eats leaves.
- A titbird can eat caterpillars.
- A bird can build its nest in a tree.
- Fungi and bacteria can break down dead leaves.
These relationships show that living things in an environment are connected. Changing one element of the environment can have consequences for several living things.
If a hedge is removed, some birds may lose nesting places, some insects may lose food sources, and some small mammals may lose shelter.
Living things interact with their environment. They depend on non-living elements like water, air, soil, light, and temperature, but also on other living things. These relationships form an ecosystem. Therefore, a change in the environment can affect the living things that inhabit it.
A living thing lives in an environment made up of living and non-living elements. Its habitat provides it with what it needs to live: food, water, oxygen for many living things, light for green plants, shelter or suitable conditions depending on the species. Green plants make their own matter using light, water, minerals, and carbon dioxide, while animals obtain their food from their environment. Living things are not distributed randomly: their presence depends on environmental factors such as humidity, light, temperature, soil, food, and shelter. In an ecosystem, living things are connected with each other and with their environment. Understanding these relationships helps us better protect nearby environments and the living things that occupy them.