Whale is an aquatic mammals which lives in the salt water. Whale is sexual dimorphism, which means the males are larger than the females, and sometimes they can look slightly different from the other. Whale 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 whale has been developed so that they can both hear on air and underwater. Therefore, if one whale is blind, it can still hunt base on the sound of its prey. Since whale can dive to a very deep level of water, it has a layer of fat under it’s skin to stay warm. Whale is a very intelligent animal which can even understand orders from human. Due to that reason, whale is usually captured to perform at the zoo to entertain people. Whale is a beautiful creature, and we should protect instead of using it as a tool.

Blue whales are the largest animals to have ever existed. They live in the cold waters of the Arctic and Antarctic but they migrate to tropical seas to breed. This breeding season lasts for about four months. Blue whales are mammals but they look like fish. They are 30 meters long and weigh about 150-200 tons. The earth's largest animal, the blue whale, usually eats very small shellfish and can eat 4 to 8 tons of krill per day. A blue whale's tongue alone can weigh as much as an elephant — its heart as much as an automobile.

There are about 14,000 blue whales in total (10,000 in the Antarctic and 4,000 in the Arctic). According to the World Conservation Union (IUCN) Red List, blue whales are classified as endangered. Blue whales have few predators but are known to be victims in attacks by sharks and killer whales, and many are injured or die each year from collisions with large ships. Their lives are also badly affected by pollution and global warming.

In order to protect blue whales and stop them from declining, there are many recovery plans that have been launched.