Animals and Their Young Ones PDF

# Animals and Their Young Ones ## How Animals Survive - Some animals, such as deer and gazelle, have very strong legs and are able to run very fast. - Some animals, such as chameleon, zebra, arctic fox, polar bear, and frog can trick their enemies because their body color blends easily with their...

# Animals and Their Young Ones ## How Animals Survive - Some animals, such as deer and gazelle, have very strong legs and are able to run very fast. - Some animals, such as chameleon, zebra, arctic fox, polar bear, and frog can trick their enemies because their body color blends easily with their surroundings. This is known as **camouflaging**. A chameleon can also change its body color according to the surroundings. Grasshopper and the stick insect are other examples of animals that show perfect **camouflage**. ### Animals in Danger - Despite a lot of adaptations, lives of several animals are in danger because of the destructive activities of humans. We are cutting down forests for our needs. By doing so, we are taking away the home and food of many animals. Thus, many animals are in danger of dying out. Some animals such as the Dodo and passenger pigeon have already disappeared from the Earth. Such animals are called **extinct animals**. Animals such as the Giant Panda and tiger are in danger of becoming extinct. Such animals are called **endangered animals.** ### Let's Remember - **T**: Animals that live on land are called **terrestrial animals.** - **F**: Animals that mostly live on trees are called **aerial animals.** - **T**: Animals that eat plants are called **herbivores.** - **T**: Panda is an endangered animal. - **F**: The sparrow is an extinct animal. ## How Animals Survive - Animals that eat plants as well as the flesh of other animals are called **omnivores**. Raccoon and humans are also omnivores. - **Scavengers** are flesh-eating animals that feed on the flesh of dead animals. They are called **scavengers**. For example, crow, vulture, and hyena. - Some small animals derive their nutrition from other living organisms. Such animals are called **parasites**. Fleas and lice (singular louse!) live on the host's body and suck blood, whereas tapeworm, roundworm, and hookworm live inside the host's body. ### Know Your Scientist - Charles Darwin He was an Englishman who gave the world the theory of evolution. He believed that living beings are different because they have undergone changes slowly over time. According to him, these changes took place in living beings because they had to struggle to survive and multiply so that their kind would survive and not die out. ### Adaptations for Protection - Many animals have adapted themselves well to the environment or to protect themselves from their enemies. An **adaptation** is a change in the features of a living being over a long period of time, which helps it survive the harsh conditions of its surroundings or escape being caught by its enemies. - Animals such as elephant and hippopotamus have thick skin to protect them from heat in hot climates. ## How Animals Survive ### Aerial Animals - Animals that can fly and spend a lot of their time in the air are called **aerial animals**. Such animals have hollow bones that make their bodies light. They have one set of limbs modified as wings to help them fly. The body shape of aerial animals is such that they are able to cut through the air easily. Almost all birds, except flightless birds, belong to this group. Bats also form a part of this group. - In the cold winter months when food becomes scarce, many birds fly towards warmer countries in search of food and warmth. This mass movement of birds from colder to a warmer place is called **migration.** ### What Animals Eat - Animals eat different types of food. Based on the type of food they eat, they can be divided into five main groups: herbivores, carnivores, omnivores, scavengers, and parasites. ### Herbivores - Animals that eat plants are called **herbivores**. Herbivorous animals have sharp teeth for biting and cutting, and very strong teeth for grinding. This is because plant food needs to be chewed a lot as it is very rich in a substance called **cellulose**, which is difficult to break down. ### Carnivores - Animals that eat the flesh of other animals are called **carnivores**. Most carnivorous animals have very sharp teeth for tearing out the flesh of its prey. Lion, tiger, snake, and lizard are examples of carnivores. ## How Animals Survive - Animals such as seal, penguin, and walrus are adapted to live in freezing conditions. They have a thick layer of fat called **blubber** under their skin to keep them body warm. - Animals that live in very cold places have thick fur on their body which protects them from the cold. Animals such as bear, frog, and snake become inactive in the cold winter months, when the food is scarce. This inactivity during winter months is called **hibernation**. - Animals living in deserts have very little hair on their body. Since there is lack of water in the deserts, some animals, such as camels, drink large amounts of water at one time so that they can survive without water for many days. - Slowing down of activity or settling down to a long sleep by some animals during the summer months is called **aestivation.** - Thus, animals have adapted to live in different climatic conditions. ### Aquatic Animals - Animals that live in water are called **aquatic animals**. Most aquatic animals breathe through gills, except whales and dolphins, that breathe through lungs.. Most aquatic animals have fins or paddles that help them to swim. Apart from fish, octopus, turtle, and crab are also aquatic animals. ### Amphibians - Animals that can live both on land and in water are called **amphibians**. The back legs of these animals are stronger than their front legs. This helps them to jump, which is how they move on land. They have webbed feet that help them to swim in water. Frogs and toads are amphibians. ### Arboreal Animals - Land animals that live mostly on trees are called **arboreal animals**. They have sharp claws to climb up and down the branches and usually have strong, muscular limbs. Some can use their tail for holding on to the branches. For example, monkey and koala. ## Where Animals Live - Animals are found everywhere: on land, on trees, flying in the air, and in water. Some animals are found on both land and water. Based on where animals spend most of their time, they can be grouped into **terrestrial, arboreal, aerial, aquatic, and amphibian animals.** ### Terrestrial Animals - Animals that live on land are called **terrestrial animals**. These animals have features suitable for life on land. They have legs which help them to walk on land, and most of them have lungs as their breathing organ. Climatic conditions may vary from place to place. It is cold on the mountains and in the polar regions, whereas it is very hot in the deserts. A yak lives on the mountains and a polar bear lives in the polar regions. A camel is found in the desert. ## How Animals Survive ### Reptiles - Most of these animals live mostly on land. But they are very adaptable and can live in various habitats, be it desert, forests, mountains, or in water. Despite changes in surroundings, temperature, and climate, their body temperature changes according to the surroundings. Examples are crocodile, lizard, snake, turtle, and tortoise. ### Birds - Birds have a light body. They are covered with feathers that are hollow, which help them to fly easy. Like reptiles, they have lungs that help them to breathe. The flightless birds, such as penguin, however, birds such as the kiwi, ostrich, emu, and cassowary do not have wings to fly because they have a heavy body. ### Mammals - Mammals are a group of animals that give birth to babies (except the platypus and anteater. Their bodies have hair and the mothers suckles their young ones. Most mammals breathe through lungs. They have four limbs. Birds and mammals are **warm-blooded animals**. This means that their body temperature remains constant despite changes in the temperature of their surroundings. Human being, elephant, horse, goat, cow, dog, and cat are examples of mammals. ## Types of Animals - Based on the absence or presence of a backbone, animals can be divided into two groups. ### Animals without a Backbone - Animals that do not have a backbone are called **invertebrates**. Examples are insects (such as cockroaches and ants), worms, slugs, and snails. Insects have six legs and their body is divided into three parts: head, thorax, and abdomen. Most insects have a hard outer covering made up of a material called chitin. A few insects, such as mosquitoes and butterflies can fly. ### Animals with a Backbone - Animals that have a backbone are called **vertebrates**. They can be further divided into smaller groups. This group consists of a large variety of animals that live in water. These animals breathe through gills. They have fins to swim. Their body is covered with scales. (Examples are cod, mackerel, and shark.) ### Amphibians - These animals live both on land and in water. Most of them breathe both through their lungs and the moist skin. (Examples are frog, toad, and newt.) ## How Animals Survive - The life-cycle of a butterfly also shows metamorphosis. The caterpillar that comes out from the egg looks very different from a fully grown butterfly. - This process of shedding the old skin is called **moulting.** The larva of a housefly is called a maggot. A baby cockroach is called a nymph. ### Know Your Scientist - Isaac David Kehimkar is known as the Butterfly Man of India. He has spent a lifetime, studying butterflies and nature. He has written many books on butterflies and won many awards for his work. He is working to popularize the concept of butterfly gardens to enable butterflies and moths to live in cities. ## Let's Remember - Label the parts of the egg correctly. Then, write the correct letter for each of the following: - **A**: A white jelly-like substance - **C**: This is a protective layer of the egg - **B**: It is the innermost part - **B**: It is rich in proteins - **A**: It is rich in fats, vitamins, and minerals - **C**: It contains food for the growing baby ## Animals and Their Young Ones - Just as our parents look after us, all other mammals look after their babies. Most mammals build houses to protect their babies from enemies, and also hunt for food. The mother feeds them and keeps them warm. - Birds, too, look after their babies. They build nests to keep them warm. Since the chicks cannot fly, parent birds get food for their chicks and also protect them from any danger. - Mammals look after their babies and protect them from enemies. ### Key words - **Reproduction**: The ability to produce more of their own kind. - **Life cycle**: Various stages of development of a living being from an embryo to a mature adult is called the life cycle. - **Caterpillar**: Larva of a butterfly is called a caterpillar. - **Metamorphosis**: A complete change from a young form to an adult form is called metamorphosis. - **Moulting**: The process of shedding the old skin is called moulting. ### Summary - Living things have the ability to reproduce. - Animals reproduce by either laying eggs or by giving birth to young ones. - An egg has a shell called the egg shell, a white jelly-like substance called album which is rich in protein, and yolk. - A baby butterfly is a caterpillar. Then it becomes a pupa, before it turns into a butterfly. - Mammals are animals that give birth to young ones. ## Animals That Give Birth to Young Ones - Some animals do not lay eggs. They reproduce by giving birth to young ones that feed on their mother's milk. Mammals are examples of such animals. - Mammals have very well-developed brains. Most mammals have hair on their body. Human beings, along with dog, cat, lion, elephant, deer, cow, buffalo, hippopotamus, zebra, giraffe, monkey, and rabbit, are some examples of mammals. Whales and dolphins are mammals found in water, but they do not have hair on their body. ### Aquatic Mammals - Most mammals live on land and breathe through lungs. Do you know how or a dolphin breathes? Whales and dolphins also breathe through lungs. They take in air through 'blowholes' present on the top of their heads. Hence, they have to go to the surface of water frequently to breathe in air. ## How Animals Survive - The mother hen lays eggs in her nest, and then sits on them to keep them warm. This helps the embryo to develop better and faster. Once the embryo within the egg has developed into a chick, the chick breaks the shell to come out. This is called **hatching.** The young chick then grows up to become an adult hen. - A frog lays eggs in water in large clusters called spawns. A tadpole which hatches out of an egg looks very different from an adult frog. It undergoes several changes through a process known as metamorphosis before it becomes an adult. (A complete change from a young form to an adult form is called metamorphosis.) ## Egg-Laying Animals - Many animals reproduce by laying eggs. The eggs are either kept in a warm place, or the parent animal sits on them to keep the eggs warm. Once the eggs mature, the young ones hatch out. Animals that lay eggs include birds, frog, fish, turtle, lizard, crocodile, snake, cockroach, butterfly, bee, mosquito, and grasshopper. - Let us learn more about how birds reproduce. ### Birds - All birds reproduce by laying eggs. Most birds build nests on trees to lay their eggs and to raise their young ones. ### Parts of a Bird's Egg - An egg has a thin protective shell called the egg shell. Within the egg shell is a white jelly-like substance called the albumen, which is rich in proteins. The yellow inner part of the egg is the yolk and it is rich in fats, vitamins, and minerals. The yolk contains food for the growing baby or the embryo. The embryo develops into a chick. - Within the egg, the embryo goes through various stages of development before the egg hatches and the chick comes out. The chic then grows into an adult. - Various stages of development, from an embryo to a mature adult, is called the life cycle of an animal. ## Let's Discuss - Why do birds need to make their nests? ## Animals and Their Young Ones - The ability to produce more of their own kind is called reproduction. Animals reproduce by two methods: - Laying eggs - Giving birth to young ones ## Circulatory System and Excretory System - Our body is made up of many organ systems. These organ systems work together so that our body can function normally. - You will learn about: - Circulatory system - Excretory system - The circulatory system is an organ system that helps to transport substances inside our body. This system consists of heart, blood, and blood vessels. - The excretory system helps in getting rid of wastes formed inside our body. The process by which wastes get removed from our body is called **excretion.** - The excretory system consists of a pair of kidneys, a urinary bladder, a pair of tubes called ureters, and a urethra. - The circulatory system transports substances throughout the body. - The circulatory system consists of the heart, blood, and blood vessels. - The heart is a muscular organ that pumps blood to all parts of the body. - Blood is a fluid that is carried by blood vessels to all parts of the body. - Blood vessels are thin tubes that run through the entire body to transport blood. - The excretory system helps in the excretion of wastes from our body. ## Solids, Liquids, and Gases - All things take up space and have mass. Any substance that has mass and occupies space is called matter. Solids, liquids, and gases are the three states of matter. - You will learn about: - States of matter - Change of states - Solute, solvent, and solution - Separation of substances ### What are Solids - Solids are substances in which the particles are packed very close to each other. Solids are usually hard and have a fixed shape. Pencil, book, chair, and marbles are examples of solids. - If we apply force, some solids can change their shape. For example, dough can be rolled out into chapatis, and interesting shapes can be made out of clay. - Some solids, on applying force, can be bent or broken. ### What are Liquids - Liquids are substances in which the particles are not very closely packed. Unlike solids, they have no fixed shape and can flow. They take the shape of the container they are poured into. Water, milk, and juices are examples of liquids. - If we pour some orange juice into a glass, it will take the shape of the glass. If we pour it into a bowl, it will take the shape of the bowl. Liquids can flow from one place to another and so are also called fluids. ### What are Gases - Gases are substances in which the particles are very loosely packed. They too have no fixed shape. Unlike liquids, they occupy all the available space in a container. Air and cooking gas are examples of gases. Air is actually a mixture of gases such as oxygen, nitrogen, and carbon dioxide. - Fluids include both liquids and gases. ## Solids, Liquids, and Gases - **Aim**: To observe the process of condensation. - **Things needed**: Mirror - **Method**: - Stand very close to the mirror and take a deep breath. - Exhale your breath onto the mirror and observe what happens. - **Observation**: The mirror becomes foggy. - **Conclusion**: The deep breath is warm and contains water vapor. This water vapor condenses into very small droplets of water when it hits the cold surface of the mirror. Several of these water droplets cause the mirror to look foggy. ## Solute, Solvent, and Solution - A solution is formed when two or more substances mix together such that they are evenly distributed. The substance that dissolves is called the **solute**. The substance in which the solute dissolves is called the **solvent**. The **solute** and **solvent** together form a **solution.** - If we add salt to water, the water turns salty. In the same way, we can add sugar to warm milk and observe what happens. - You will see that in both the cases, the salt and the sugar mix with the liquid and dissolve in it. - Here, salt and sugar are the solutes, water and milk are the solvents, and the salty water and the sweet milk are solutions. - **Solute + Solvent = Solution.** - Sugar + Milk = Sweet milk - Salt + Water = Salty water ## Solids, Liquids, and Gases - **A**: Substances that completely dissolve in a solvent. - **B**: Substances that do not completely dissolve in a solvent. - **C**: The process in which insoluble substances settle down. - **D**: The process in which a solution containing insoluble substance is passed through a filter paper. - **S**: Soluble in water - **I**: Insoluble in water - Sand: **I** - Salt: **S** - Sugar: **S** - Stone: **I** ## Solids, Liquids, and Gases - Matter can change its form from one state to another. - The process by which a solid changes into a liquid is called **melting.** When you take out an ice cube from the freezer and leave it at room temperature, you will see that the ice starts to melt into water. - When this water is heated further, water starts to changing into vapor (steam). - The process by which a gas changes into a liquid on cooling is called **condensation.** When you hold a cold steel plate over a pot of boiling water, you will see tiny drops of water condensing on the tray. - The process by which a liquid changes into a solid on cooling is called **solidification.** Freezing of water into ice is a form of solidification. If you fill water in an ice tray and keep it in the freezer, you will see that after some time the water turns into ice. ## Let's Discuss - Rani's scarf got wet in the rain. What could be the quickest way to dry her scarf? - Rain is formed when water changes its form from one state to another in nature. Discuss how rain is formed. ## The State of Matter - All matter (or substances) is made up of small particles. These particles are arranged in different ways in solids, liquids, and gases. #### Solids - Solids are substances in which the particles are packed very close to each other. Solids are usually hard and have a fixed shape. Pencil, book, chair, and marbles are examples of solids. - If we apply force, some solids can change their shape. For example, dough can be rolled out into chapatis, and interesting shapes can be made out of clay. - Some solids, on applying force, can be bent or broken. #### Liquids - Liquids are substances in which the particles are not very closely packed. Unlike solids, they have no fixed shape and can flow. They take the shape of the container they are poured into. Water, milk, and juices are examples of liquids. - If we pour some orange juice into a glass, it will take the shape of the glass. If we pour it into a bowl, it will take the shape of the bowl. Liquids can flow from one place to another and so are also called fluids. #### Gases - Gases are substances in which the particles are very loosely packed. They too have no fixed shape. Unlike liquids, they occupy all the available space in a container. Air and cooking gas are examples of gases. Air is actually a mixture of gases such as oxygen, nitrogen, and carbon dioxide. - Fluids include both liquids and gases.