Five Kinds of Chordates

First, the animals living in water that we know they are fishes. Fishes are poikilothermal, because they could charge their blood temperature with the temperature of the surroundings. Fishes were the earliest vertebrates and presumably evolved from a group of aquatic lower chordates; the terrestrial vertebrates evolved from fishes. Fishes can not live on the land, because they can not breathe on land. For example, if you take a fish out the water, you will discover that fish die in later. The reason is fishes breathe through gills only under the water. Fishes lay eggs for birth under the water, they have scales cover their bodies, and they can see everything behind them through their eyes. And Fishes have the b

In conclusion, fishes, amphibians, reptiles, birds, and mammals are the 5 kinds of chordates that we know. Each kind of chordates has their common and differences between each others, the common characteristics make them belong the same group, but these differences create their own distinguishing characteristic of each kind.

Third, reptiles are the poikilothermal animals that we know. The reason why they are poikilothermal is they lack an effective system for regulating their body temperature, which tends to approach that of the environment. They live in the warm and temperate regions, with the greatest variety in the tropics, but some are adapted to living in water. Reptiles typically have low-slung bodies with long tails, supported by four short legs that project outward from the sides of the body; however, some reptiles do not limbs. For example, all snakes do not have any limbs. They breathe air by means of lungs and have thick, waterproof skins designed for retaining body moisture. Unlike amphibians, they do not possess gills or breathe in water at any stage of their development, and they lay their eggs on the land. Also, Reptiles have the back bone on their back.

Fourth, birds are the warm blooded animals having their body covered with feathers and their forelimbs modified into wings,

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