The Blue Whale is the largest mammal to have ever graced this earth. Weighing in at up to 180 tonnes and with a body length of 25 to 30 meters, the size of these graceful creatures is hard to fathom! Before whaling the Blue Whale populations around the world were extraordinarily healthy with the largest population found in the isolated waters of Antarctica with an estimated 240,000 Blue Whales. The largest animal in the world feeds on one of the smallest creatures in the world, Euphausia superba which is also known as Antarctic Krill.
The oldest ever recorded Blue Whale was estimated at 110 years old and the average lifespan for a Blue is between 80-100 years old. A female Blue Whale will generally have only one calf every 2-3 years and her gestation period is 10-11 months. Migrating north to the warm waters found off Indonesia in the Banda Sea, a female Blue Whale will give birth to a calf that weighs in at 2,500 kilograms and seven meters long. A Blue Whale calf happily consumes 350 litres of milk every day and this large quantity of milk and its high fat content allows the calf to put on 90 kilograms every 24 hours…that is just over 3 kilograms every hour!
Calves will stay with their mothers for approximately 6-8 months and at this time they are around 16 meters long and ready to be weaned from their mothers. They will live a fairly solitary life once they have left their mothers and during those first eight months of life they have learnt everything they will need to live the life of an Antarctic Blue Whale. Depending on the individual they will generally reach sexual maturity around 5-10 years of age and when fully grown the female Blue Whale is larger than the male by a couple of meters.
Blue Whales will travel continuously throughout the year to reach feeding grounds that provide the quantities of krill they require. The Perth Canyon in Western Australia is one of only three known aggregation areas in Australian waters that Blue Whales are known to feed at. Once they have arrived at their feeding grounds they will focus all of their efforts into consuming as much krill as possible leading to extraordinary figures. When large quantities of krill are abundant a Blue Whale can easily consume up to four tonnes of krill every day which works out to around 3o million krill. A mouthful of water and krill weighs in at 50 tonnes before the water is filtered out and the krill get trapped in the baleen plates, sometimes a few unfortunate squid and small fish get caught up in the feeding bonanza resulting in a bit of extra protein for the Blue Whale!
An enormous lung capacity of 5,000 litres allows the Blue Whale to easily hold their breathe for up to 30 minutes or more if needed. When feeding they will dive to where the krill are located, usually around 100 meters, and feeding dives can be between 10 – 20 minutes long. Resurfacing after these feeding dives you can see an exhalation that ranges between 9 to 12 meters in height as the Blue Whale replenishes their oxygen levels before beginning their next dive. Migrating Blue Whales that are travelling to feeding or breeding grounds generally travel 13 meters below the surface to avoid unnecessary drag at speeds of 20kph. Male Blue Whales that are defending a female they are courting can reach speeds of up to 50kph in short bursts while chasing another male away. This incredible speed from such a large animal often results in a powerful breach of the head and upper body of the Blue Whale as they surface to breathe during these powerful chases.
Almost hunted to extinction over many years of whaling, the Blue Whale population found in Antarctica was estimated at only 360 individuals when whaling finally ceased in the 1970’s. Today we can see a very slow increase in Blue Whale numbers but still not at the same rate as other species, such as the Humpback Whale. Although they are the largest animal on earth there is very little known about the Blue Whales found in our oceans and their day to day life.
These magnificent creatures have certainly captured the imagination of people all over the world and much research is being done to learn everything we can about our Blue Whales and help them continue to grow their population back to much healthier levels. They are certainly survivors and adapt whenever they are faced with a problem, their mystery and elusiveness adds to their allure and meeting a Blue Whale is the greatest privilege and a highlight of ones life!