Cetacea are one of the most unique orders of mammals. They include the largest marine animal that has ever lived which is the blue whale, the intelligent dolphins, the tusked narwhals and the singing humpback whales – almost eighty living species in all. Even though a lot of hunting has been done to the family of Cetacea, observations has been dictated that its number are slowly increasing.
The oldest fossil whales are grouped together just for the convenience of others. Archaeocetes are the oldest whales and it shows several differences to the modern whales. Modern whales either lack teeth or have teeth but are all identical in shape and size. Archaeocetes had nostrils like the mammals instead of a blowhole like what modern whales have now.