Fish

The Fish is the largest group of vertebrates. There are about 20,000 species of fish around the world living in the oceans, rivers, streams, and lakes. The Fish is a cold-blooded vertebrate. Their body temperature changes when the temperature changes around their environment.

They have fins and breath with their gills underneath the water. They take water in through their mouth and then it flows through the gills. The oxygen in the water will be trapped by thin tissues covering the gills and then enters with the fish’s blood and the carbon dioxide passes into the water. The water flows out to the openings in the Fish’s side.

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A hard scale protects its body. On each side of the Fish, there is a sense organ called the Lateral lines. It feels vibration from boats, people, and other objects in the water. They have also a very powerful sense of smell.

Amphibian

The second group of cold-blooded vertebrates are the amphibians. In  the first phase of their life, they live with water and breath with their gills. When they grow up they begin to develop their lungs and move up to land. Some of the amphibians can lay thousand of eggs at one time. Their eggs don’t have shells but have jelly around them. Their eggs must be keep in water to be able for them to live.

Reptile

The third group of cold-blooded vertebrates are the reptiles. Most of the reptiles are covered with hard, dry, and rough scales. They lay their eggs with shells. Some of the reptiles such as the alligator and crocodiles lies in the shore to warm their bodies in the sun. This reptiles usually hunts for fishes and other animals in  the water.

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Another type of reptile is the Turtle. Some of them live on land and others live in the water, such as the Sea Turtles. Sea Turtles use to lay their eggs hundreds of miles away from their feeding areas. They use to lay their eggs on the beaches and leave them.

Birds

The birds are warm-blooded vertebrates. Their body temperature will not change and remains the same even if the temperature of the surrounding environment changes. They lay their eggs with shells. This vertebrate have a very light bone yet very strong and their bodies was shaped for flying purposes. birds can fly because they are very light, they have wings, and they have approximately 25,000 feathers all over their bodies.

Some birds developed an oily feather such as those of the Penguins and Ducks, this makes them waterproof which helps a lot for their survival.

Mammals

The fifth group of animals are the mammals and belong to the warm-blooded animals. mammals use to feed their young with their milk. They also have hair or fur. Most of the mammals usually lives on land. There are also mammals who live in the water such as the Whales. Others likes to stay in the land and in water like the Walrus.

The mammals developed inside the bodies of their mother, unlike other vertebrates that developed outside in the forms of eggs.