In addition to erroneously calling the sperm whale the largest mammal on the planet (that would be the blue whale), Barney tells Chano that the sperm whales throat is only a few inches wide. In fact, the sperm whale, which hunts and eats large squid and other prey, has a much larger throat than most other great whales.
Barney calls the sperm whale the largest mammal on Earth. The blue whale is the largest mammal on Earth.