The blue whale -- a member of the group of whales known as the baleen whales -- is the largest known animal, growing to a length of up to 110 feet and weigh up to 190 tons. They can be found throughout the world's oceans, though they particularly favor the cold waters found in the North Pacific, North Atlantic, and Antarctic Oceans. Due to its immense size and its aquatic environment, both of which have exerted various pressures, the blue whale has developed a number of adaptations that have allowed it to survive.
Due to its immense dietary needs, blue whales expand their throats in order to take in as much as 50 gallons of water. They then strain the water out through large plates called baleen, which allow the water to flow out and the krill (tiny organisms) to be digested. A blue whale can eat up to four to six tons of krill in a single day.
Blue whales possess two blow holes on the top of the head, which enables them to hold their breath for long periods underwater. The blow holes have seals that keep water out during their dives. Unlike humans, which only exchange 17 to 20 percent of their lung air with each breath, a whale will usually exchange 80 to 90 percent. Furthermore, the spout of water and air can shoot up to 30 feet into the air.
Hearing and Seeing Adaptations
Since light and sound travel differently underwater than they do on land, blue whales have developed a number of adaptations to see and hear differently than their terrestrial counterparts. Whales have a highly developed sense of hearing and they depend on it in much the same way that human beings depend on their eyes. Furthermore, since swimming requires whales to be streamlined as much as possible, they do not have external ears. Instead, they utilize an internal system of bones and sinuses to detect sound.
Diving and Sleeping Adaptations
Since they would drown if they slept deeply, blue whales have developed the ability to take short naps that allow them to float near the surface of the water. They have also developed a number of adaptations that allow them to dive into deep waters, including a decreased heart rate while diving, blood is diverted to the heart, lungs, and brain, and they have a higher concentration of red blood cells than terrestrial mammals. Dives can last up to twenty minutes.