Blue whales live in all the world’s oceans and they are mammals. They breathe air and their babies born alive. These amazing mammals often spend summers feeding in polar waters and can reach speeds of 50 kilometres per hour. Blue whales are the largest animals on the Earth. These magnificent marine mammals are 30 meters long and they weight about 200 tons. The upper sides are grey with a thin white border; the lower sides are white. The flippers are 3–4 metres. Their tongues alone can weigh as much as an elephant and their hearts, as much as an automobile. They can hear each other up to 1,600 kilometers away and swimming in small groups but usually alone or in pairs. During certain times of the year, a single adult blue whale consumes about 4 tons of krill a day.The blue whale has very poor eyesight. Whale fishing was more popular some decades ago because they needed meat, oils, and bones for their life and it was hunting prize too. In 20th century the blue whale was nearly exterminated. More than 350,000 were killed by whaling fleets. Now whale hunting is illegal but dangerous are always poachers, big ships which can injure blue whales and global warming. In 1966, the IWC banned commercial whale hunting. Since this year blue whales are endangered species. Exist many organisations which care about safety Blue whales. For example International Whaling Commission (IWC). we should spread information about our the biggest mammals on the world. We can help!