Adaptation of Living Things to Their Environment – JSS2 Basic Science Lesson Note (First Term)

Adaptation is a feature of the body or behaviour of a living thing that helps it to survive in its habitat.

Behavioural objectives

By the end of the lesson, students should be able to:

1. define adaptation and acclimatisation;
2. describe how animals are adapted to aquatic habitats;
3. describe how plants are adapted to water, desert and temperate grassland habitats;
4. list the physical adaptations of frogs to life in wetlands;
5. name the biotic and abiotic components of a habitat and state the importance of each abiotic component.

What is adaptation and how do living things adapt?

Adaptation is the ability of living organisms to adjust to their surroundings through changes in structure or behaviour.

• Habitat: the place where a plant or animal lives, such as a pond, a desert or a grassland.
• Body changes: special body parts that suit the habitat, such as the fins of a fish.
• Behaviour changes: ways of acting that help survival, such as hibernation and aestivation.
• Location changes: moving to a more suitable place, as some animals do when conditions change.
• Different habitats: different organisms adapt in different ways.

How are animals adapted to aquatic habitats?

Aquatic animals live in water and have special body structures, called adaptational features, that suit life there.

1. Streamlined body: the smooth, tapered shape reduces water resistance and makes swimming easy.
2. Respiratory organs: fishes breathe with gills. Air-breathing animals have nostrils near the top of the head, so they can breathe at the surface.
3. Locomotory organs: fins, webbed feet, paddles and flippers help the animal move in water (see below).
4. Scales: scales cover the body of fishes and protect the soft organs inside. The slippery surface helps the fish to escape from enemies.
5. Air bladder: some fishes have this organ. It lets the fish adjust to different depths by increasing or reducing the gas inside it.

What are the swimming organs of aquatic animals?

Swimming organs are body parts that help aquatic animals to move through water.

• Fins: used by fishes to swim, balance and steer.
• Web: a thin fold of skin between the toes of the hind limbs of amphibians such as frogs. It increases the surface area for swimming.
• Paddles: fin-like limbs used for swimming by turtles.
• Flippers: the swimming limbs of whales.

How are plants adapted to their habitats?

Plants are adapted to their habitats by features that help them to live and grow in that particular place.

• Limited range: an adaptation that suits one place may make survival hard in another.
• Example 1: a cactus cannot live in the Arctic.
• Example 2: very tall trees do not grow well in grasslands.

How are aquatic plants adapted?

Aquatic plants are plants that grow in water, and they are adapted to support, light and moving water.

• Flexible stems and leaves: underwater parts move with the water currents without breaking.
• Air spaces: air spaces in the stems help to hold the plant up in the water.
• Weak transport system: submerged plants have little transport tissue in the stem. They absorb water, nutrients and dissolved gases through the leaves directly from the water.
• Reduced roots: roots and root hairs are small or absent. Roots only anchor the plant and do not need to absorb water.
• Floating leaves: some leaves lie on top of the water and receive sunlight. The water lily is an example.
• Chlorophyll on the upper surface: in floating leaves the green colour is on the top, where sunlight hits. The upper surface is waxy and repels water.
• Floating seeds: some plants produce seeds that float, so water can carry them to new places.

How are desert plants adapted?

Desert plants are adapted to survive with very little water and strong heat.

What is the desert habitat like?

• Rainfall: less than 10 inches (about 250 mm) a year, and it often falls all at once.
• Sunlight: a lot of direct sunlight reaches the plants.
• Soil: often sandy or rocky, so it holds little water.
• Wind: strong, dry winds dry out plants.
• Temperature: plants face extreme temperatures and drought, so they must cope with heavy water loss.

What are the adaptations of desert plants?

• Succulents: store water in their stems or leaves. A cactus stores water in its stem.
• Few or no leaves: some plants have no leaves, or small leaves that grow only after rain. This reduces water loss. Leafless plants photosynthesise in their green stems.
• Long roots: roots spread out wide or go deep into the ground to absorb water.
• Short life cycle: some plants germinate after rain, grow, flower and die within one year. They avoid the drought.
• Hairy leaves: leaf hairs help to shade the plant and reduce water loss.
• Turning leaves: some leaves turn during the day to expose the smallest area to the heat.
• Spines: spines stop animals from eating the plant to get water. A cactus has spines instead of leaves.
• Waxy coating: a layer of wax on stems and leaves reduces water loss.
• Night flowers: flowers that open at night attract pollinators that are active in the cooler night.
• Slow growth: slow growth needs less energy, so the plant makes less food and loses less water.

How are temperate grassland plants adapted?

Temperate grassland, also called prairie, has hot summers, cold winters and uncertain rainfall, and its plants are adapted to drought, fire and grazing.

What is the temperate grassland habitat like?

• Rainfall: about 10 to 30 inches of precipitation a year. Drought is common.
• Soil: very rich in organic material, because the above-ground parts of grasses die each year and enrich the soil.
• Use: the land suits farming, so few original prairies survive today.

What are the adaptations of prairie plants?

• Surviving roots: in a fire the above-ground parts of grasses may die, but the roots survive and sprout again.
• Thick bark: some prairie trees have thick bark that resists fire.
• Resprouting shrubs: prairie shrubs readily sprout again after a fire.
• Deep roots: grass roots go far into the ground to absorb as much moisture as possible.
• Extensive roots: wide root systems stop grazing animals from pulling the plant out of the ground.
• Narrow leaves: narrow leaves lose less water than broad leaves.
• Growth from the base: grasses grow from near the base and not the tip, so grazing or fire does not damage them permanently.
• Wind pollination: many grasses are wind-pollinated, which suits the exposed, windy land.
• Soft stems: soft stems bend in the wind.

How are frogs adapted to life in wetlands?

Frogs have ten main physical adaptations that help them live in and near water.

What is acclimatisation?

Acclimatisation is the ability of an organism to make small changes in its body, over a short period, to suit a new surrounding.

• Example: people who visit high mountain ranges may suffer altitude sickness, because the air holds little oxygen at that height.
• Result: after some time their bodies adjust, or become acclimatised, to the new conditions.

What is the difference between adaptation and acclimatisation?

Adaptation is a lasting feature of a kind of organism that suits its habitat. Acclimatisation is a short-term adjustment made by one organism in a new place.

What are the components of a habitat?

A habitat has two types of components: biotic (living) and abiotic (non-living).

What are biotic components?

Biotic components are all the living things in a habitat.

• Plants: make food by photosynthesis.
• Animals: feed on plants or on other animals.
• Microorganisms: very small living things such as bacteria.

What are abiotic components?

Abiotic components are the non-living things in a habitat, and they provide the conditions that living things need to survive.

Air

• Plants and animals take in oxygen from the air for respiration.
• Plants take in carbon dioxide for photosynthesis.
• Air contains nitrogen, which bacteria change into forms that plants can use.
• Moving air cools the body.
• Wind can carry seeds to distant places and can be used to generate energy.

Soil

• Soil is the topmost layer of the earth.
• It is rich in minerals and microorganisms that help plants to grow.
• It has spaces that hold water, which plants absorb.

Water

• About three-fourths of the earth is covered with water.
• Water is essential for life and is the medium for many reactions inside the body.
• Water can be freshwater or marine (sea) water.
• Animals that live in water are aquatic organisms. Plants that live in water are hydrophytes.
• Humidity and rain are also forms of water that help living things.

Sunlight

• The sun is the main source of energy for living things on Earth.
• Plants use sunlight to make food by photosynthesis.
• Animals depend on plants for food, so they depend on sunlight indirectly.

Temperature

• Temperature at a place depends on the sunlight it receives.
• It also affects the humidity of the place.
• A place may be too hot, moderate or too cool.
• Some animals hibernate in the cool winter, and some aestivate in the hot summer.

Evaluation

1. Define adaptation.
2. State four adaptational features of aquatic animals.
3. List five adaptations that help desert plants to reduce water loss or survive drought.
4. Why do prairie grasses survive fire and grazing?
5. What is the difference between biotic and abiotic components of a habitat? Give two examples of each.

Assignment

Describe five adaptations of plants that live in water, and explain how each one helps the plant to survive.