NCERT Summary: Gist of Biology - 9 Notes | EduRev

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(ii) Amphibians

Amphibians lay their eggs in water, and young amphibians tend to resemble small fish. The tadpole, or newborn frog, is born and lives in water. It has a tail that allows it to swim like a fish. It also has gills so that it can breathe under water. As the tadpole grow into a frog, it loses its gills and tail, and develops legs for moving on land. Most amphibians can both walk and swim in water.

Depending on the species of amphibian, breathing can take place in gills, lungs, the lining of the mouth, the skin, or some combination of these. 

Amphibians body temperature changes with its environment. In cold climates, amphibians hibernate during the winter. There are over 6,400 species of amphibians found worldwide, except in Antarctica and Greenland. Amphibians are vertebrates and include animals such as frogs, toads, salamanders, newts and worm-like caecilians. They can be found on land, and in fresh water. They live in a variety of habitats from deserts to rain forests, permanent ponds or high mountain meadows. Most amphibians have four limbs, but some amphibians don’t have any limbs. Amphibians are cold-blooded meaning they use the environment to regulate their body temperature. Amphibians spend part of their life in water, and part of their life on land.

(iii) Reptiles: African Clawed Frog
The African Clawed Frog is native to South Africa, the sub-Saharan in east and southern Africa, and Namibia and Angola in western Africa. Their habitat includes warm stagnant pools and quiet streams. Their name comes from the three short claws on each of its hind feet. It spends most of its time underwater, only coming to the surface to breathe. African clawed frogs don’t have tongues. The frog’s uses its front limbs and unwebbed fingers to push food into its mouth.

(a) Poison Dart Frog
The poison dart frog is a family of frogs native to Central and South America. Their habitat is humid, tropical areas such as tropical rainforests. They may live on the ground as well as in trees. Most poison dart frogs are brightly colored, which makes them easily recognizable and warns potential predators to stay away. Why do the predators stay away? As their name implies, this frog is highly poisonous. They secrete a toxin through their skin that is capable of killing a predator. Many species are critically endangered

(b) Frog
There are over 5,000 species of frogs. They are native to most of the world, except Antarctica. Generally, we think of frogs as having a short, stout body with long hind legs ideal for jumping. Most of us can recognize a frog’s call as the familiar croaking or ribbit sound. Another common characteristics is that frogs don’t have tails. The various species also have a wide range of different characteristics. Some frogs are small, such as the Coqui. Other frogs can be quite large. Some frogs are even poisonous, such as the Poison Dart Frog.

(c) Reptiles: Lizards, Snakes, and Others
Reptiles have been around for 300 million years, even during the dinosaur age. The most common reptiles include alligators, crocodiles, lizards, snakes, tortoises and turtles. Reptiles are air-breathing animals, although many live not only on land but in water. The most noticeable feature of reptiles are the scales that cover their body. The majority of reptiles lay eggs to give birth to their young. Although reptiles breathe through lungs, some reptiles can also absorb oxygen in water through membranes in their mouth.
Reptiles are often called cold-blooded because they can’t regulate their own body temperature. Their body temperature depends on the external temperature. They will lay in the sun to heat their body, or hide in the ground, under a rock or in water to cool their body.
Crocodiles and alligators are large reptiles that spend much of their time on land and in water. They can walk on land using their webbed feet. They can also use their long tail to swim in water. Crocodiles feed on large animals they catch on land or in water. They have powerful jaws and teeth to tear apart their prey. Lizards and snakes are the largest group of reptiles. Lizards are four legged animals with a long tail. Many lizards can shed their tail to escape from predators. They can then grow a new tail. Some lizards, such as the chameleon, can change colors to blend into their environment. This camouflage helps to protect them from predators. Snakes don’t have limbs. They move by slithering along the ground. Some snakes are poisonous, or venomous, such as the rattle snake, cobra, and eastern green mamba. They have fangs which bite into their prey and inject poison into the victim. Other snakes, such as the boa constrictor and the python kill their prey by crushing it. Most snakes can dislocate their jaw, allowing them to swallow prey much larger than themselves. 

(d) Alligator
The alligator is native to the United States and China. Alligators are covered with scales, head to toe. They can grow up to fifteen feet long and weigh over one thousand pounds. Based on fossils, the alligator has been on earth for 200 million years. They have a very strong jaw, capable of crushing their prey. Alligators are cold-blooded. They lay eggs to produce their young.

(e) Anaconda Snake
The anaconda is a large, non-venomous snake native to tropical South America and Northern Africa. They mostly live in swampy or watery areas. The green anaconda is the biggest snake in the world, with the largest measuring up to 37.5 feet in length. The anaconda is related to the boa constrictor snake. They kill their prey by constriction or squeezing. They wrap themselves around their prey and squeeze to prevent the prey from breathing. They then swallow the animal whole.

(f) Chameleon
The chameleon is a member of the lizard family native to Africa, Madagascar, southern Europe, and Asia. There are about 135 different species of chameleon. Their habitat includes rain forest, savanna, semi-desert, and steppe land. Chameleons are best known for their ability to change color. However, they don’t really change color to match their surroundings, but based on mood, such as fear or anger, and based on temperature and humidity. They are also known for their ability to move each eye separately, and for their long, sticky tongue. Their eye can rotate 360 degrees to view its prey, they its fast, sticky tongue can catch its prey.

(g) Cobra Snake 
The cobra is a venomous snake native to Africa and Asia. There are about 30 different species of cobra, with the King Cobra being the world’s largest venomous snake. The cobra’s habitat ranges from tropical rain forests and swamps to savannas and deserts. The name cobra is Portuguese for “snake with hood.” Cobra’s are most famous for this hood, which is created by elongated ribs that extend the loose skin of the neck behind the snake’s head. Cobras will raise the front part of their bodies and display their hood when threatened or disturbed. They will also make a hissing sound.

(h) Crocodile 
The crocodile is native to tropical areas in Africa, Asia, the Americas and Australia. The crocodile is an ancient, prehistoric creature, believed to have inhabited earth for over 200 million years. The name crocodile comes from an Ancient Greek word meaning “lizard of the river.” Crocodiles prefer freshwater habitats like rivers, lakes and wetlands. Crocodiles are similar to alligators and caiman. They are very fast over short distances, even out of water. They catch their prey by waiting for fish or land animals to come close, then rushing out to attack.

(i) Coral Snake 
The coral snake is a venomous snake native to southern United States including Arizona and from Louisiana to North Carolina, including all of Florida. Coral snakes are small in size, averaging 3 feet in length. They are a very beautiful snake with their red, yellow/white, and black colored banding. They are the second most venomous snake in the United States, behind the rattlesnake. 

The iguana is a family of lizards native to tropical areas of Central and South America and the Caribbean. The green iguana, which is a popular pet, lives in tropical rainforest areas near water, such as rivers or streams. Other iguanas live in the dry, hot desert. Like other reptiles, the iguana is cold blooded meaning they do not produce their own body heat. If an iguana is cold, it will lie on warm rocks to soak up the sun’s heat. Green iguanas are omnivorous meaning they eat both plants and meat, but they mostly eat plants.

(j) Komodo Dragon 
The komodo dragon is a lizard native to islands in Indonesia. They are a member of the monitor lizard family. They are the largest of the lizards, growing up to 10 feet in length and weight over 200 pounds. It is carnivorous, eating animals such as pig and deer. It is also cannibalistic, eating other komodo dragons. The komodo dragon has even been known to attack and kill humans. They are now an endangered species.

(k) Lizard
There are over 5,000 different types of lizards in the world. They are native to every continent, except Antarctica. Most lizards are small and harmless to humans. But, the large Komodo Dragon has been known to attack and kill humans. Lizards have some of the strangest characteristics. Some lizards can walk on water. Others can lose their tail to escape a predator. Others can squirt blood from their eyes. The Chameleon can change colors to match its surroundings. The Chinese Water Dragon can not only swim to escape predators, but it can remain under water for up to 25 minutes. Some lizards are small, but others such as the Monitor Lizard can grow up to 6 feet in length. Lizards such as the Gila Monster are venomous. And, some lizards such as the Gecko and the Iguana are common pets.

(l) Mamba Snake
The black mamba is native to Africa. Their habitat is open grasslands, savannahs and woodlands. It is the largest venomous snake in Africa and the second largest venomous snake in the world. They are considered the deadliest snake in Africa. They are also considered fastest land snake in the world, able to reach speeds of 12 miles per hour. Although they are called the black mamba, they are generally gray, gray brown, or olive green in color. The name black mamba comes from the black color inside their mouth.

(m) Viper Snake 
The viper is a family of venomous snakes found all over the world, except in Australia and Madagascar. Vipers range in size from the small dwarf viper which is 10 inches in length, to the large bushmaster at 10 feet in length. Vipers have a pair of fangs that are used to inject venom from glands in the rear of the upper jaws. These fangs are hinged, and when not in use fold back against the roof of the mouth.

(n) Turtle 
Turtles are a reptile found in most parts of the world. Some turtles live on land, while others live in the sea. They are easily recognized by their shell. The turtle’s shell is covered with scales made keratin, the same material as human fingernails. Many turtles can retract their head and limbs into their shell for protection. The largest turtle, the leatherback sea turtle, can have a shell length of 80 inches. A small turtle may be only 3 inches long. Turtles have a beak, not teeth. Female turtles lay eggs to reproduce their young. 

(o) Tortoise
The tortoise is a reptile, closely related to the turtle. The tortoise is often described as a land turtle. Turtles usually live in water and have large blade-shaped flippers for swimming. Therefore, turtles find it hard to walk on land. Whereas, the tortoise has legs rather than flippers and can walk quiet well on land. Like the turtle, the tortoise has a large protective shell. Tortoises can have longer life span that humans, sometimes living to be over 150 years old. 

(p) Sea Turtle 
Sea turtles are native to all the world’s ocean, except the Arctic Ocean. The largest sea turtles are seven feet in length and five feet in width, weighing up to 1300 pounds. Some sea turtles are believed to live to be 80 to 100 years old. Sea turtles spend much of their time under water, but must return to the surface to breathe air. All species of sea turtles are listed as threatened or endangered. (q) Sea Snake Sea snakes are found in warm, tropical, coastal waters of the Indian Ocean and Pacific Ocean. A few species are also found in Oceania. Sea snakes are venomous snakes, and have fangs. Sea snakes are highly adapted to living in the water. For example, they have a paddle-like tail for swimming. Although these snakes spend most of their time in the water, they must come to the surface to breathe air

(r) Pitviper Snake
The pitviper is a family of venomous snakes found in Eastern Europe, Asia and the Americas. Their habitat ranges from desert to rainforests. Pitvipers have a deep pit between the eye and the nostril on either side of the head. This is an organ that detects heat from warm-blooded prey. Common pitvipers include the bushmaster, copperhead and rattlesnake

(s) Python Snake
The python snake is native to Africa, Asia and Australia. Burmese pythons were introduce to the Florida Everglades National Park in the 1990s. The python is one of the largest snakes in the world. The reticulated python may grow to over 30 feet long and weight over 300 pounds. The python generally feeds on small reptiles and mammals, but has been know to eat deer and other large animals. The python kills its prey by constriction. It wraps itself, or coils around its prey suffocating the animal by preventing it from breathing.

(t) Rattlesnake
Rattlesnakes are venomous snakes native to North America and a few other parts of the Northern Hemisphere. They get their name from the rattle located at the tip of their tails that is used as a warning device when threatened. The rattle is a set of rings on the tip of their tail. When vibrated, the rattle creates a hissing sound that warns off predators. Rattlesnakes use their venomous bite to catch and kill prey such as mice, rats, small birds and other small animals.  

There are about 8,000 species of known reptiles alive today. The first reptiles appeared approximately 340 million years ago during the Carboniferous Period. Reptiles are cold-blooded. Reptiles have scales. The Mesozoic Era is the ‘Age of Reptiles’. In many reptiles, the sex of the young is determined by the temperature the embryos are exposed to during incubation. Some of the largest reptiles alive today include the leatherback turtle, the Komodo dragon, and the saltwater crocodile. 


There are over 8,000 species of birds. Birds have 3 major differentiating characteristics: wings for flight, feathers, and a beak rather than teeth. Birds have adapted their vertebrate skeleton for flight. Their bones and skull are very thin, making their bodies extremely light. To support flight also required other changes to their skeleton. Obvious changes are the addition of wings. Other changes are less obvious. The claws and muscles of a bird’s foot are designed to lock and hold onto a perch even while the bird is sleeping. A bird’s respiratory system is also adapted to make it easier to breathe at high elevations, where air is thinner. More information on birds

(a) Albatross
The Albatross is a large sea bird found near the Southern Ocean and North Pacific. The albatross is among the largest flying birds, and has the largest wing span. Its large wings are excellent for flying, but can make taking off and landing quite difficult. 

(b) Swan

Swans are a family of birds native to many parts of the world including the Americas, Europe, Asia, Africa and Australia. Swans are the largest of the waterfowl compared to ducks and geese. The largest swan in the world is the trumpeter swan of North America whose wingspan can reach 10 feet. The habitat of the swan is ponds, lakes, coastal bays and rivers. They are easily recognized by their very long necks which are often held in a graceful curve. Their long necks allow them to feed underwater without diving 

(c) Vulture
Vultures are native to the Americas, Africa, Asia, and Europe. They are scavenging birds feeding mostly on carrion, that is carcasses of dead animals. Vultures have a good sense of smell, and can smell a dead animal from great heights. One recognizable characteristic of many vultures is their bald head with no feathers

(d) Ruby-Throated Hummingbird
The ruby-throated hummingbird is native to: the Canadian prairies; eastern Canada, United States and Mexico; Central America; and, parts of South America. Its habitat is deciduous and pine forests and forest edges, orchards, and gardens. The hummingbird has strong flight muscles and blade-like wings allowing it to fly not only forward, but also straight up and down, sideways, and backwards, and to hover in front of flowers as it feeds on nectar and insects.

(e) Parrot
Parrots are native to most warm and tropical parts of the world including Australia and the islands of the Pacific Ocean, India, southeast Asia, southern regions of North America, South America and Africa. There are about 372 different species of parrot. Parrots are one of the smartest birds. Not only can they mimic human speech, studies have shown they can associate words with their meanings and form simple sentences 

(f) Ostrich
The ostrich is a large flightless bird native to Africa. It is easily recognized by its long neck and legs. The ostrich is a fast runner, capable of reaching speeds up to 45 miles per hour. A large male ostrich can weight up to 350 pounds. Matching its size, ostrich eggs are the largest of all eggs. Penguins are a group of aquatic, flightless birds mostly living in the Southern Hemisphere, particularly the Antarctica. However, the Galápagos Penguin prefers a more temperate climate living near the equator. Penguins are easily recognizable by their black and white coloring, and their unusually upright, waddling gait. The penguin looks like it is formally dressed in a man’s tuxedo. These birds have adapted for life in the water. Their wings have become flippers allowing them to swim fast in the water.

(g) Peacock
Peacocks are large colorful pheasants. Although most people know this bird by the name peacock, this name specifically refers to the male bird. The female is called a peahen. Collectively they are referred to as peafowl. There are three species of peafowl. The blue peacock lives in India and Sri Lanka, the green peacock lives in Java and Myanmar, and the Congo peacock lives in African rain forests. The peacock is best known for its known and valued for its brilliant tail feathers. This iridescent blue-green or green colored tail plumage, also called the train, has bright spots on it called “eyes” 

(h) Kiwi
The kiwi is a flightless birds native to New Zealand. It is an endangered species. They are an interesting looking bird with a plump body and a long bill. Kiwi are shy and usually nocturnal. The kiwi is a national symbol of New Zealand. They are so well known to the world, and representative of New Zealand, that all New Zealanders are called “Kiwis”. 

(i) Hornbill
Hornbills are a family of birds native to tropical and sub-tropical Africa and Asia. They can be found in open country as well as forested areas. The most distinctive feature of the hornbill is their heavy bill. It is long and down-curved, and often brightly-colored. Hornbills are omnivorous birds meaning they will eat fruit, insects and small animals. They cannot swallow food from the tip of the beak because their tongue is too short. They must toss it to the back of their throat.

(j) Great Blue Heron
The great blue heron is a large wading bird common over most of North and Central America, as well as the West Indies and the Galápagos Islands. They live near bodies of water such as fresh and saltwater marshes, mangrove swamps, flooded meadows, lake edges, or shorelines. They build their nest in trees or bushes near the water. They are often seen standing in shallow water or at the water’s edge. They use their long legs to wade through the water, and they spear fish or frogs with their long, sharp bill. 

(k) Golden Eagle
The Golden Eagle is a large bird of prey living in North American and other parts of the northern hemisphere. It is one of the best known birds of prey in the Northern Hemisphere. It is powerful and strong with a wingspan of over 7 feet.

The golden eagle’s eyesight is about 8 times more powerful than a human, and can spot prey from a long distance. Their talons are well designed for killing and carrying their prey. They also have a powerful beak for tearing into its food.

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