There are some very well known blue whale facts, like the fact that it is the largest mammal on the earth. There also some things that are less well known. For example, how large they actually are. The longest blue whale recorded was a female which was caught in the Antarctica and measured 
108 feet from nose to tail. She probably weighed around 150 tons. A more normal weight for a blue whale in the Southern Hemisphere is 80 – 100 tons. In the Northern Hemisphere they tend to be a little smaller and it would be rare to find one more than about 80 feet in length.
When it comes to feeding, you would expect the largest mammal on the planet to eat something fairly substantial from the food chain. One of the most surprising blue whale facts is about their diet. Not only do they not eat large fish, but they opt for some of the smallest fish and live almost entirely on tiny prawn like animals called krill. Needless to say, they do have to consume quite a number of these krill to satisfy their dietary needs and can get through around 40 million a day. That is about 4 tons – the same weight as a Ford Excursion SUV.
One of the saddest blue whale facts is regarding their numbers. The early whalers were unable to hunt the whale because of its size. It was just too big for them to be able to deal with successfully. However, once the whalers improved the design of their harpoons and learnt how to inflate the whales so that they would not sink after being shot, their numbers dropped dramatically. In one season it was reported that 29,000 were killed. This was in 1931 when their slaughter was at its most prolific. The economics of using the blue whale meant that they had become a highly sought after commodity, with a decent sized carcass giving up to 120 barrels of oil. It was only after 99% of the entire blue whale population had been slaughtered that the International Whaling Committee banned all hunting of the mammal and gave those that were left total protection. This was in 1966 and still there is only approximately 8,000 – 14,000 alive on the planet.
The gestation period for a whale is 12 months and the calves are usually born 2 to 3 years apart. Therefore their population increase is going to be a slow process. Their maturity is measured by size rather than by age. For example, they become sexually mature between 74 – 79 feet. Their young are weaned once they reach 52 feet. This is another one of those wonderful blue whale facts of which most of us are unaware.
Because these graceful heavyweight mammals are not often visible to us, many of us think of them as being almost mythical. It is hard to imagine creatures of this size living on the same planet and being out of sight. There are many blue whale facts that will fascinate you and the more we learn about these elegant giants the greater their chances of surviving, despite our previous ignorant mistakes.