Many Fish Swap Sex Organs
With so many land creatures to wonder at, it's easy to forget that some of the weirdest activities take place deep in the ocean. The strange practice of hermaphroditism is more common among species of fish than within any other group of vertebrates. Some fish change sex in response to hormonal cycle or environmental changes. Others simultaneously possess both male and female sex organs.

Elephants Do Forget, but They're Not Dumb
Elephants have the largest brainenearly 11 pounds on averageeof any mammal that ever walked the earth. Do they use that gray matter to the fullest? Intelligence is hard to quantify in humans or animals, but the encephalization quotient (EQ), a ratio of an animal's observed brain size to the expected brain size given the animal's mass, correlates well with an ability to navigate novel challenges and obstacles. The average elephant EQ is 1.88. (Humans range from 7.33 to 7.69, chimpanzees average 2.45, pigs 0.27.) Intelligence and memory are thought to go hand in hand, suggesting that elephant memories, while not infallible, are quite good.