The blue whale is the largest animal to ever live, in the entire history of Earth. Reaching lengths of at least 110 feet (33 meters) and weights of 209 tons (190 tonnes), these animals are only slightly smaller than the United States Space Shuttle. Their incredible size is only possible because of their aquatic lifestyles and the buoyancy provided by seawater. On land, an animal as large as the blue whale would almost certainly be crushed under its own weight.
These whales are distributed globally, including off both coasts of the continental United States. Some populations stay in the same place year-round, but most migrate to the poles in the summer to feed and move back toward the equator in the fall. Blue whales prefer the open ocean, but can sometimes be seen offshore of coastal states.
Despite their huge size, blue whales feed on relatively small prey, primarily tiny shrimp-like animals called krill. Like some other whales, blue whales possess baleen—stiff plates made of hairlike structures—in place of teeth. When they feed, they expel seawater out of their mouths through the baleen, and the krill stay trapped inside. A blue whale can eat up to 7,715 pounds of krill per day. Young blue whales consume 100 to 150 gallons of milk each day from their mother.
Blue whales tend to be more solitary than other whale species. They can, however, sometimes been see them together in small groups of two to four individuals.
Blue whales cruise the ocean at about 20 miles per hour. Their vocalizations can be heard from 1,000 miles away. These vocalizations are thought to be used as communication as well as sonar navigation.
Breeding occurs during the winter months in warm waters near the equator. The gestation period is about a year, during which time adults migrate to the poles to feed. Females return to winter breeding grounds to give birth. Newborn calves are an impressive 23 feet long, and they pack on 200 pounds a day by drinking their mother’s milk. They will reach reproductive maturity at 10 years of age. The whale’s estimated lifespan is between 80 and 90 years.
Blue whales are federally listed as endangered. This species was once abundant, but advances in whaling technology made it easier for people to hunt them. With the rise of factory ships, blue whale populations plummeted. They are now protected internationally by a moratorium on whaling, and their numbers are rising. Ship noise, entanglement, and collisions may affect them in areas with high human activity, but occurrences of these events are rare. The effect that climate change will have on blue whales is uncertain.
Interestingly, though they are enormous, blue whales are not predatory. They filter feed for tiny krill and are totally harmless to people (other than through accidental collisions). This life history strategy is common among several large animals in the ocean, including the whale shark, the basking shark, and the other great whales. Like all whales, blue whales are mammals and give live birth to very large calves that they nurse for six or seven months. Because the female is responsible for providing milk for its babies, she must store extra energy reserves and is consequentially larger than males. All of the record blue whales (by size) are females. Males do not provide parental care and do not seem to live near the females/young for most of the year.
Blue whales have a truly global distribution and live in every ocean except the parts of the Arctic that remain covered with ice throughout most of the year, including summer. There are three distinct populations of blue whales (North Atlantic, North Pacific, and southern hemisphere), and individuals are known to undergo very long migrations between feeding grounds near the poles and calving grounds in the tropics. Their very large size may help blue whales (and other migrating animals) survive such long trips through waters that may provide relatively little food.
Unfortunately, blue whales were one of the hardest hit species by commercial whaling, and they have been slow to recover since their worldwide protection in 1966. Experts continue to view them as endangered (highly vulnerable to extinction) and estimate their numbers to be only three to ten percent of what they were before whaling. Today, a primary threat to blue whale recovery is accidental interactions with fishing gear and with ships, but their numbers are slowly increasing. To compound their trouble, however, blue whales’ preferred food source – krill – is now fished commercially. Their recovery from commercial whaling is in direct competition with commercial fishers in the Southern Ocean. As that fishery takes more and more krill, the slow increase in numbers of blue whales may stop or even be reversed.
Fun Facts About Blue Whales
1. Blue whales are the largest animals to ever live on the planet, reaching maximum lengths of 110 (33.5 m) feet and weights of 330,000 pounds (150 metric tons).
2. Blue whales can live for 80 to 90 years on average.
3. Blue whales are the loudest animals on the planet capable of producing sounds that can be heard by other blue whales up to 1,000 miles away.
4. Blue whales can eat up to 12,000 pounds (5.4 metric tons) of krill in a day.
5. Blue whales swim 5 miles per hour on average but can swim more than 20 miles per hour in short bursts.1