Facts on the Age of Blue Whales

Lifespan

• Blue whales have one of the longest average lifespans of any animal on Earth, sharing the honor of longevity with creatures like the Galapagos tortoise. With an average lifespan of between 80 and 90 years, researchers can spend their own lifetime following the life of the same blue whale. The oldest whale on record is 110 years old, though it is entirely possible that there are other similarly long-lived individuals that are never identified.

  Marine biologists have found an accurate way to determine the age of a whale at death. By performing an autopsy that includes dissection of the waxy plugs in the creature's ears, the animal's age at death can be estimated by counting the layers of wax.

Reproductive Age

• When female blue whales are between 6 and 10 years old, they reach reproductive age. They can have a calf every two to three years. Researchers have found that the frequency of calving may increase in response to reduction in numbers due to outside threats such as whaling. Males reach maturity slightly sooner, and are capable of reproduction at between 4 and 5 years old. By this age, both male and female whales have almost reached their adult size -- usually between 66 and 75 feet long, with males being slightly smaller than females. Newborn calves are typically between 20 and 25 feet in length.

Maturity

• Calves are heavily dependent on their mother for the first part of their lives. They nurse from their mother for the first six months of life, when they can consume 50 gallons of milk a day. This high-fat milk allows them to gain about 250 lbs. a day; this means that in the first six months of life they can add around 45,000 lbs. to their original birth weight of about 3 tons. Calves are weaned at six months old, and typically stay near the mother for another six months.

Effects on Age

• The average age of a blue whale is based on the idea that they have few natural predators aside from humans. There have been records of blue whales being killed by sharks, but the largest factor in the premature death of whales is hunting. This can be in the form of both whaling and collisions with ships, as large ships often pass through whale territory and are unable to avoid the creatures. Many countries have banned whaling, but the fishing industry still has the potential to decrease the amount of food available; an adult whale can consume 4 tons of fish and krill in a single day.

  The whale's blubber-rich body was the cause of their status as a favorite target for whalers. Largely because they are so large at such a young age, a single young whale could be a profitable kill, causing hundreds of thousands of blue whales to be killed in the beginning of the 20th century.