Organisms and Their Surroundings

Living organisms, or creatures, are found almost everywhere on Earth. From the cold Himalayan mountains to the hot Rajasthan deserts and humid sea beaches, every location, no matter how different, is teeming with life. Living creatures have even been found in extreme environments like the openings of volcanoes. Each of these different regions has its own unique set of plants and animals.

For example, deserts have camels, mountains have goats and yaks, and the sea is home to crabs and a vast variety of fish. While some organisms like ants are found in many different locations, the majority of plants and animals are specific to their particular surroundings. The non-living things in these regions, such as soil, rocks, and water, also vary greatly.

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Biotic and Abiotic Components

The surroundings or environment of any organism can be divided into two main components:

• Biotic Components: These are all the living things in an environment. This includes all plants, animals, and microorganisms.
• Abiotic Components: These are all the non-living things in an environment. This includes rocks, soil, air, water, sunlight, and heat.

Abiotic factors like air, water, light, and heat are crucial for the growth and survival of all living organisms. For example, seeds need these factors to germinate and grow into new plants.

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Examples of Components in Different Surroundings

Surrounding	Biotic Components (Plants & Animals)	Abiotic Components (Other objects)
In the Forest	Trees (Oaks, Pines), Animals (Lion, Deer), Insects, Birds	Soil, Pebbles, Dried leaves, Bones, Water
In the Desert	Cactus plants, Camels, Rats, Snakes	Sand, Rocks, Hot & Dry Air
In the Sea	Fish, Crabs, Squids, Algae, Casuarina trees	Saline (salty) water, Sand, Rocks

Habitat and Adaptation

The surroundings where an organism lives is called its habitat. The word habitat means a dwelling place or a home. A habitat provides an organism with everything it needs to survive, such as food, water, air, and shelter.

Organisms have certain features or habits that enable them to live successfully in their specific habitat. This process of developing specific features to survive in a particular environment is called adaptation.

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Types of Habitats

Habitats can be broadly classified into two main types:

1. Terrestrial Habitats: These are habitats found on land. There is a large variation among them.

   Examples: Forests, grasslands, deserts, coastal regions, and mountain regions.

2. Aquatic Habitats: These are habitats found in water.

   Examples: Oceans, seas, lakes, rivers, and ponds.

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Examples of Adaptation

Adaptation in a Camel (Desert Habitat)

A camel is well-adapted to survive in the hot and dry conditions of a desert:

• Long legs: Keep its body away from the hot sand.
• Water conservation: Excretes very small amounts of urine, has dry dung, and does not sweat. This allows it to survive for many days without water.

Adaptation in a Fish (Aquatic Habitat)

A fish has several features that help it live in water:

• Streamlined body: Its body tapers at both ends, which helps it move easily through water with minimum resistance.
• Slippery scales: Protect the body and aid in smooth movement.
• Fins and tail: Help in changing direction and maintaining balance.
• Gills: Special respiratory organs that allow the fish to absorb oxygen dissolved in water.

Because of these specific adaptations, a fish cannot live out of water, and a camel cannot survive in the sea.

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Acclimatisation vs. Adaptation

It's important to distinguish between adaptation and acclimatisation.

• Adaptation: These are permanent changes that occur over thousands of years in a species, making them suitable for a particular habitat. Organisms that cannot adapt die out.
• Acclimatisation: These are small, temporary changes that happen in the body of a single organism over a short period to adjust to a change in its surroundings. For example, when a person from the plains goes to a high mountain, they may have difficulty breathing initially, but after a few days, their body adjusts. This is acclimatisation.

A Journey Through Different Habitats

Let's explore the specific adaptations of plants and animals in some major terrestrial and aquatic habitats.

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Terrestrial Habitats

1. Deserts

• Animals: Animals like rats and snakes, which do not have long legs like a camel, stay away from the intense daytime heat by living in deep burrows in the sand. They are nocturnal, coming out only at night when it is cooler.
• Plants (Cacti):
  • Leaves: The leaves are either absent, very small, or modified into spines. This reduces water loss through transpiration.
  • Stem: The thick, green, fleshy part of a cactus is its stem, which carries out photosynthesis and stores water. It is covered with a thick waxy layer to help retain water.
  • Roots: They have very long roots that go deep into the soil to absorb water.

2. Mountain Regions

These habitats are very cold and windy, with snowfall in winter.

• Trees: Mountain trees like pines and deodars are typically cone-shaped with sloping branches. Their leaves are often needle-like. This shape helps rainwater and snow to slide off easily, preventing damage to the tree.
• Animals:
  • Animals like yaks have long hair, while snow leopards have thick fur (including on their feet and toes) to protect them from the cold.
  • Mountain goats have strong hooves that help them run up rocky slopes.

3. Grasslands

• Predators (Lion): A lion's light brown colour helps it hide in dry grasslands (camouflage). Its eyes are in the front of its face, giving it a correct idea of the location of its prey. It has long, retractable claws for hunting.
• Prey (Deer): A deer has long ears to hear the movements of predators. Its eyes are on the sides of its head, allowing it to look in all directions for danger. It has strong teeth for chewing hard plant stems and is very fast, which helps it run away from predators.

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Aquatic Habitats

1. Oceans

• Many sea animals like fish have streamlined bodies.
• Animals like squids and octopus stay deep near the seabed. When they need to move, they can make their body shape streamlined.
• Mammals like dolphins and whales do not have gills. They breathe through nostrils or blowholes located on the upper part of their heads. This allows them to breathe in air when they swim near the surface.

2. Ponds and Lakes

• Plants:
  • Some plants have their roots fixed in the soil at the bottom, with long, hollow, and light stems that allow the leaves and flowers to float on the surface (e.g., lotus).
  • Some plants are completely submerged. Their leaves are often narrow, thin, and highly divided to allow water to flow easily without damaging them.
  • In most aquatic plants, roots are much reduced as their main function is to hold the plant in place, not absorb nutrients.
• Animals (Frog): Frogs are amphibians, adapted to live both on land and in water. They have strong back legs for leaping and webbed feet which help them swim.

Characteristics of Living Organisms

How do we distinguish between living and non-living things? While a moving car is non-living and a stationary plant is living, the distinction is not always obvious. Living things share a set of common characteristics that set them apart from non-living things.

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1. All Living Organisms Need Food

All living things require food to get the energy they need to grow and perform various life processes. Plants make their own food through photosynthesis, while animals depend on plants or other animals for their food.

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2. All Living Organisms Show Growth

Growth is a common characteristic of all living things. A baby grows into an adult, a pup grows into a dog, and a small sapling grows into a large tree. Growth is a permanent increase in size. Non-living things, like clouds, may appear to grow, but this is not true growth; it's just an accumulation of more material.

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3. All Living Organisms Respire

Respiration is a necessary process for all living organisms. It is the process through which the body obtains energy from food. It involves the exchange of gases: taking in oxygen and giving out carbon dioxide.

• Animals: Humans and many other animals breathe through lungs. Fish use gills to absorb oxygen dissolved in water. Earthworms breathe through their moist skin.
• Plants: Plants also respire day and night. They take in air through tiny pores on their leaves, use the oxygen, and release carbon dioxide. (This is separate from photosynthesis, where they use carbon dioxide and release oxygen during the day).

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4. All Living Organisms Respond to Stimuli

Living things respond to changes in their surroundings. These changes are called stimuli (singular: stimulus). The reaction of the organism to a stimulus is called a response.

• Animals: Wild animals run away from a bright light (stimulus). Cockroaches scurry to hiding places when a light is switched on (stimulus). We pull our hand away when we touch a hot object (stimulus).
• Plants: Plants also respond to stimuli. The shoot of a plant grows towards sunlight (stimulus). The leaves of a 'touch-me-not' (Mimosa) plant fold when touched (stimulus).

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5. All Living Organisms Excrete

Our bodies produce waste products during various life processes. The process of getting rid of these wastes from the body is known as excretion. This is a characteristic common to all organisms. Plants also excrete, but their mechanisms are different; they may store waste in parts that do not harm the plant or remove them as secretions (like gum or resin).

More Characteristics of Living Organisms

Beyond the fundamental characteristics, there are a few more traits that define living beings.

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6. All Living Organisms Reproduce

Reproduction is the process by which living things produce more of their own kind. This ensures the continuation of their species.

• Animals: The mode of reproduction varies. Some animals, like birds, lay eggs from which young ones hatch. Others, like mammals (cows, dogs, humans), give birth to live young ones.
• Plants: Plants also reproduce in different ways.
  • Through seeds: Many plants produce seeds which can germinate and grow into new plants.
  • Through other parts: Some plants can reproduce from parts other than seeds, like a bud of a potato or cuttings from a rose plant. This is called vegetative propagation.

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7. All Living Organisms Move

Movement is another sign of life.

• Animals: Animals move from one place to another (locomotion) for food, shelter, or to escape from danger. They also show other body movements.
• Plants: While plants are anchored in the soil and do not show locomotion, they do show movement. They transport water, minerals, and food within their bodies. Flowers open and close, and plants bend towards light.

Non-living things like a car or a bus can also move, but this movement is caused by an external force (an engine) and is not a characteristic of life itself.

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8. All Living Organisms Die

Another common characteristic is that all living beings have a finite lifespan and eventually die. Because individual organisms die, reproduction is essential for a species to survive over thousands of years.

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What Then is Life?

In general, something is considered living if it exhibits all the characteristics we have discussed. Non-living things may show one or two of these characteristics (like movement or apparent growth) but not all of them simultaneously.

However, the line can sometimes be blurry. A dry seed in a shop may not show any signs of life like growth, respiration, or excretion for months. But when we plant it in soil and give it water, it germinates and grows into a full plant. The seed was alive but in a dormant or inactive state. Inside a sack, seeds respire and produce a small amount of heat, indicating that a life process is still occurring.

While it may not be easy to define "life" in a single sentence, by observing the incredible diversity and common characteristics of living beings around us, we can conclude that life is a complex and beautiful phenomenon.

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