Some interesting facts about animals include that elephants have the largest brain of any mammal ever, many species of fish change gender depending on need, and beavers live 29-hour days during the winter. Because elephants have such large brains, they tend to remember things better than other animals.
Fish have ways of adapting to environmental changes by either being hermaphroditic, which means containing both male and female sex organs, or changing gender as found in oysters. Other types of marine life have interesting characteristics such as the three hearts found in octopuses and the individual names with which dolphins identify each other. Blue whales alone have several interesting characteristics including being the loudest mammals with their low-frequency sounds and their tongues that weigh as much as a single elephant alone.
Birds are unique as well; some interesting facts about birds deal with the eye tubes of the owls and seagulls that prey on whales. Owls have elongated eyeballs that most closely resemble binocular tubes, helping them to judge distances effectively. Seagulls hunt southern right whales along the coast of Argentina, attacking them in droves and tearing off hunks of flesh.
The largest penguins on Earth, the colossus, once stood well over 6 feet tall although it is now extinct.