Baleen whales are a widely distributed and diverse parvorder of carnivorous marine mammals. They include 15 species from the families Balaenidae (including right whales), Cetotheriidae (the pygmy right whale), Eschrichtiidae (the gray whale), and Balaenopteridae (the rorquals, including the blue whale, the largest animal on earth). Cetaceans were thought to have descended from the extinct mesonychids, but molecular evidence supports their descent from even-toed ungulates. Baleen whales split from toothed whales around 34 million years ago. The meat, blubber, baleen, and oil of baleen whales have traditionally been used by the indigenous peoples of the Arctic. Once relentlessly hunted by commercial industries for these products, cetaceans are now protected by international law, but Japan, Norway and Iceland continue to allow whaling for various purposes. Baleen whales also face threats from marine pollution, ocean acidification, collisions with ships, and entanglement in nets. Sonar can cause strandings and disrupt their communication. They have rarely survived for long in captivity. (Full article...)