Diversity in the Living World: Class 6 Science Notes on Habitats, Adaptations, and Biodiversity

The world around us is full of living things — from tiny bacteria to giant banyan trees and elephants. This study note helps you understand how we identify living things, why they live in different places, and how they adapt to survive. We will also see why biodiversity matters and how scientists group organisms for study.

Living or Non-Living? The Real Checklist

To decide whether something is living, we cannot rely on a single feature. A stone may appear to 'grow' when mud sticks to it, and a car moves and burns fuel, but neither is alive. Living things show a set of life processes together, and these processes are the real checklist for life.

• Nutrition: All living things take in food to get energy and materials for growth.
• Respiration: They use oxygen to release energy from food, though some organisms use other methods.
• Excretion: They remove waste products formed inside the body.
• Growth: They increase in size by adding new cells or material.
• Movement: They can move their body parts, and many can move from place to place.
• Response to stimuli: They react to changes around them, such as light, heat, or touch.
• Reproduction: They produce young ones of their own kind.

Non-living things may show one or two of these features, but they never show all of them together. For example, a cloud grows bigger and moves, but it does not eat, respire, excrete, or reproduce. Therefore, the presence of all essential life processes together tells us that something is alive.

Habitat: The Home of an Organism

A habitat is the natural home of an organism — the place where it lives, finds food, and raises its young. Every habitat has two kinds of components. The non-living parts, such as soil, water, air, sunlight, and temperature, are called abiotic components. The living parts, such as plants, animals, and microbes, are called biotic components.

• Terrestrial habitats are on land: forests, grasslands, deserts, and mountains.
• Aquatic habitats are in water: ponds, lakes, rivers, and seas.
• Some organisms, like birds, spend much time in the air, but they still depend on land or water for nesting and food.

No single habitat is suitable for every organism. A cactus cannot survive in a pond, and a fish cannot live in a hot desert. The features and behaviours that help an organism survive in its own habitat are called adaptations. Adaptations may be in the body shape, colour, skin, limbs, or even in behaviour such as migration and hibernation.

How Plants Adapt to Their Habitat

Plants also adapt to their surroundings. In deserts, water is scarce and temperatures are high. A cactus has leaves reduced to spines to reduce water loss, a thick fleshy stem to store water, and deep roots to absorb water from deep in the soil. Its green stem performs photosynthesis, so the plant does not need large leaves.

• Aquatic plants: Water lily has broad, waxy leaves that float on water, and its stems have air spaces that keep the plant afloat. Roots are short because water is easily available.
• Mountain plants: Trees like pine have a conical shape so snow slides off easily, and needle-like leaves reduce water loss and resist cold.
• Grassland plants: Many grasses have long, narrow leaves and strong roots that help them survive grazing and fire.

These features are not acquired in one lifetime; they develop over many generations. This is why a cactus planted in a rainy area may still show desert adaptations. Adaptation is a slow, inherited change that makes a plant better suited to its habitat.

How Animals Adapt to Their Habitat

Animals show even more visible adaptations. A camel lives in hot deserts, so it has long legs to keep its body away from hot sand, nostrils that can close against sand, and a hump that stores fat for energy when food is scarce. Its broad feet stop it from sinking into loose sand.

• Aquatic animals: Fish have streamlined bodies, gills for breathing in water, and fins for swimming. Frogs have moist skin and webbed feet for moving in water.
• Polar animals: Polar bears have thick fur and a layer of fat called blubber to keep them warm in cold regions.
• Forest and grassland animals: Deer have strong legs to run fast, and large ears to hear predators. Lions have sharp claws and teeth for hunting.

Some adaptations are behavioural. Birds migrate to warmer places in winter, and some animals hibernate to save energy when food is scarce. These behaviours, along with body features, help animals survive in their specific habitats.

Biodiversity and Classification: Organising Nature

The variety of living organisms found in a particular area is called biodiversity. A forest has high biodiversity because it supports many kinds of plants, animals, and microbes. Biodiversity is important because every organism has a role in nature: plants produce oxygen, bees pollinate flowers, and decomposers break down dead matter.

• Classification is the grouping of organisms based on similarities and differences.
• Animals with a backbone are called vertebrates; animals without a backbone are called invertebrates.
• Plants can be grouped into flowering and non-flowering plants.

Classification makes the study of millions of organisms easier and helps us see relationships between different groups. We must protect biodiversity by conserving habitats, planting trees, and avoiding pollution. If we destroy habitats, many species may disappear forever, and the web of life gets broken.

Key takeaways

• Living things show all essential life processes together: nutrition, respiration, excretion, growth, movement, response to stimuli, and reproduction.
• A habitat includes both biotic (living) and abiotic (non-living) components; each organism is suited to its own habitat.
• Adaptations are inherited features or behaviours that help an organism survive in its habitat, such as cactus spines or camel humps.
• Plants and animals show different adaptations in deserts, water, mountains, grasslands, and polar regions.
• Biodiversity is the variety of living organisms in an area, and it is essential for a healthy environment.
• Classification groups organisms based on similarities and differences, making the study of nature easier and more organised.

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