Mammals Class 4 Notes Science

Mammals

1. They have hair on the body.
2. Mammals are warm blooded hence they can regulate temperatures.
3. They have sweat glands to cool the body by taking heat from the body.
4. Mammals give birth to young ones.
5. They have mammary gland to feed the young ones.
6. Mammals have four legs to walk on.
7. They have more developed brain than other.
8. Mammals have flippers and fins (If aquatic) instead of legs for swimming.

Bat is the smallest mammal size less than 2 cm 

Blue whale is biggest mammal of all

Look at the following diagram of types of Mammals

Adaptations in Mammals:

Hibernation
Squirrels, mice and polar bear etc. go underground or in burrows to avoid extreme cold condition in winter. This is an adaptation to weather.

Stripes on the Body
Tiger, Zebra, and Cheetah have stripes on their body to help them hide among grasses and leaves so that they can easily kill their prey (Adaptation for catching prey and self protection)

Fig: Stripes on the body for self protectionSharp Spines on the Body
Porcupine have sharp spines all over its body to protect themselves from their enemies (adaptation for self protection).

Fig: A porcupine
Prehensile Tail and Opposable Thumb
Monkeys, Chimpanzee live on trees and have prehensile tail and opposable thumb to hold branches of the tree (Adaptation to aerial habit).  

Feeding in Mammals
Deer, goat, cow, squirrels, rats, etc. are herbivorous, which eat only plants and plants' product. Tiger, lion, cheetah etc are carnivorous which feed on other animals like deer, goat etc. Human being is omnivorous as it eats both plants and animals.

Reproduction in Mammals
Both male and female are mainly needed sexual mode of reproduction Young ones are similar in structure and behavior to their parents. Parents take care of their babies till it is matured enough to take care of itself. Cheetah cubs fully rely on their mother for food and protection.

Fig: A mother caring her baby

Migration in Mammals
Whales migrate from warm tropical waters far north or south for the brief summer where food is in excess.

Commonly Asked Questions:
Giraffe is a mammal and all mammals including humans have same number of bones on neck. How many bones are present in its neck?
(a) Seven
(b) Eight
(c) Nine
(d) Six
(e) None of these
Answer; (a)
Explanation: A Giraffe has seven bones in its neck just like other mammal but the giraffe's neck bones are much longer. Therefore, option (A) is correct and rest of the options is incorrect.

You Must Know:

1. By the age of six a child knows more than 2,500 different words.
2. Hector's dolphin is sometimes called the Mickey Mouse dolphin, because its dorsal fin is shaped like this famous cartoon character's ears.
3. Wild horse no longer lives wild. It is rare and kept mainly in parks and nature reserves.
   Blue whale is 33.5 m log.
4. The arctic tern travels more than any other bird.

Animals:
All animals breathe, feed and move. The place where an animal lives, eats, grows and reproduces is called its habitat.

Breathing
All animals need to breathe for their survival. When an animal breathes in oxygen and breathes out carbon dioxide, an exchange of gases takes place.
Fish
A fish lives in water. The water passes out through a pair of gill-slits on each side of its body. As this water passes over the gills, the fish takes in oxygen and releases carbon dioxide, which flows out with the water. The oxygen gets absorbed into the blood of die fish.
Whale
A whale looks like a fish and lives in water; but it is not a fish. A whale does not have gills. It has lungs. To breathe, it must come up to the surface of the water to fill its lungs with air. A whale has very large lungs so that it can take in enough oxygen in one breath to last for some time under the water.

Fig: Whale reaching the surface to breathe

Frog
A frog breathes through its lungs on land as well as through its moist skin under water.
A baby frog or tadpole breathes through its gills.

Fig: Frog (An Amphibian)

Insects
Insects like cockroaches, caterpillars and grasshoppers breathe through tiny air holes, called spiracles on their bodies. The spiracles of the body lead to air tubes which form a network that reaches every part of an insect’s body. Air enters the body through this network. The body parts take in oxygen and give out carbon dioxide. The blood of insects does not have the oxygen carrier called haemoglobin. That is why their blood is not red in colour.

Some animals like earthworms can take in oxygen through their thin moist skins.

Fig: A Caterpillar having spiracles on its body

Fig: A Cockroach

Amoeba and paramecium are tiny animals which can be seen only through microscope. They breathe through their body surface.

Humans: Humans too breathe through their lungs. We have a pair of lungs in our chest. We breathe through our nose. When we breathe in air, the lungs expand and fill with air. When we breathe out, the chest contracts and pushes out the air with the carbon dioxide from the body.

Fig: Inhalation and Exhalation in Humans

Eating Habits                 

All living things need food to get energy, to grow and to stay healthy. Different animals eat different kinds of food. Some animals eat plants. Some eat the flesh of other animals. Some animals eat both plants and other animals. Animals have different types of teeth based on the type to food they eat. Animals are classified on the basis of their eating habits as below:

Carnivores

Animals like lion tiger and cat eat meat. They have sharp and pointed teeth called canines to tear meat and strong grinding teeth to chew flesh and break bones.

Frogs feed mostly on insects like flies and beetles. The frog uses its sticky tongue to capture its prey. The tongue is fixed in the front and free from behind.

Fig: Some Carnivores animals

Carnivores birds: Eagle, kite and owl have strong, sharp hooked beaks and sharp claws.

The claws help them to hold the meat and tear it. They are carnivorous birds.

Fig: Carnivores Birds

Herbivores   

Some animals like cow, goat and giraffe eat plants. They have sharp front teeth called incisors to cut plants and strong broad teeth called molars to chew food.

Fig: Herbivores Animals

Rodents

Animals like squirrel, rabbit and mouse eat seeds and fruits. They have small and sharp front teeth which help them to gnaw food.

Fig: A Rodent

Omnivores

Some animals like bear, crow, including human, eat plants as well as meat. They have incisors and molars to help them eat both kinds of food.

Fig: Omnivores

Movement

Every animal moves so that it can:

• Search for food
• Run and protect itself
• Build a home or look for a shelter where it can rest and breed.

Animals have different types of body parts or limbs for movement and different & ways of moving from one place to another.                                 

Most animals usually have four limbs. The two in the front are called forelimbs and the two at the back are called hind limbs. Some animals like horses use all the four limbs to move, while others use only the hind pair.