Dolphin is an aquatic mammals which lives in the salt water. Dolphin is sexual dimorphism, which means the males are larger than the females, and sometimes they can look slightly different from the other. Dolphin has streamlined body with two limbs which are modified into flippers which can help it to swim at the speed up to 50km/h. It has conical sharp teeth to catch small but fast - moving prey. The hearing ability of dolphin has been developed so that they can both hear on air and underwater. Therefore, if one dolphin is blind, it can still hunt base on the sound of its prey. Since dolphin can dive to a very deep level of water, it has a layer of fat under it’s skin to stay warm. Dolphin is a very intelligent animal which can even understand orders from human. Due to that reason, dolphin is usually captured to perform at the zoo to entertain people. Dolphin is a beautiful creature, and we should protect instead of using it as a tool.

Dolphins are mammals living in the ocean and waterways have a close relationship with whales. There are nearly 40 species of dolphins belonging to 17 genera living in the oceans, the remainder living in some rivers in the world (Yangtze River, Amazon River, Indian River, Ganges River, ...). The size of dolphins can range from 1.2 m (4 ft) and 40 kg (90 lb) (Maui dolphins), up to 9.5 m (30 ft) and 10 tons . Dolphins are one of the intelligent animals and are well known in human culture for their friendly appearance and mischievous attitude. Dolphins are found all over the world and often inhabit the shallow seas of the continental shelf. Dolphins are carnivores, mainly eating fish and squid.