I generally write in this column about Iowa native wildlife. I suppose that is because I can relate to those most easily. They are the ones I see and many times experience in some way. I have stories to share about woodchucks or eagles or snakes.
But with close to 50,000 species of mammals, birds, fish, reptiles, and amphibians in the world, you know that there is a wealth of animals to write about outside of our Iowa borders. I don't even need to add that there are close to a million species of insects to add to the world's animal total, but I guess I just did.
So this week, I decided to gather some information for a column on the world's largest mammal the blue whale. This is an animal most definitely not on the list of Iowa mammals.
It turns out, blue whales are considered to be the largest animals that have ever existed on Earth. A blue whale can reach almost 100 feet in length and it can have a weight of more than 200 tons. A medium blue whale can weigh 160 tons and is the equivalent of 30 elephants ,or 1600 people. But despite their huge dimensions, the eyes of a blue whale are just the size of a teacup, and their external ear is just as big as the tip of a pencil! Their heart is a different story. The heart of a blue whale can weigh about 1,300 pounds - the size of a small car.
And of course, they live in the ocean. They are part of the baleen whales category which means that they eat very small animals (mostly a shrimp like creatures called krill although anything in the big gulp of water is a part of the meal) that they filter through the large bony plates (baleen) in their mouths. A large blue whale can hold 46,000 liters of water in its mouth. It doesn't swallow all that water, but instead passes it through the baleen keeping the food part and letting the rest go on back out to sea.
Blue whales can be found in all oceans, but the largest populations of blue whales can be found in the North Pacific and the North Atlantic oceans. Blue whales have been victims of excessive hunting over the years and they were on the verge of extinction.
It is very easy to kill too many because the populations grows very slowly. Sexual maturity lasts from only 5 to 10 years and a female can give birth to a baby blue whale only every two or three years. Babies are born in warm waters during winter days. Pregnancy lasts from 10 to 12 months. When the baby is born, it grows very quickly. A blue whale baby can drink up to 600 gallons of milk a day. This milk is 50 per cent fat nearly ten times that of human breast milk.