The animal kingdom is home to some amazing traits. Cheetahs can run at 70 mph (112 kph) [source: Enoch]. Camelscan survive half a year without a water source [source: California Academy of Sciences]. Frogscan freeze in winter and then thaw, alive, in spring [source: Roach].
As far as superlative animal talents go, these are just a few of the better known. There are plenty that haven't become common knowledge yet, and some of them are exceptionally gross, frightening, awkward, or seemingly impossible. Some are so anthropomorphic you have to laugh.
Here, we've collected 10 of those crazy facts, and we bet even animal-trivia buffs will be surprised by at least a few. You may laugh, you may deny. You'll almost certainly say "awww" more than you'd like. You may even squirm: We human types can be a little squeamish when it comes to, say, a penis with four heads.
And that's only the beginning of that one.
Odd penisesaren't unique in the animal world – and to the animals sporting them, of course, they're not odd at all. Snakeshave two half-penises that join when it's time to mate [source: Medical Dictionary]. Sea-slug penises are disposable [source: Kaplan]. Catpenises are barbed [source: Dell'Amore].
But the echidna, often called a "spiny anteater," tops them all. The Australia-area native sports a single shaft with four heads, each one capable of ejaculation. Only two of the heads function at any given time, though, which makes sense since the female echidna has "only" two vaginas. During copulation, one side of the penis is inactive, its two heads retracted, while the other side is ready to fertilize the female's eggs. After ejaculation, the male echidna activates the other side and repeats the process [source: Cooke].
It starts with hen anatomy. A female chicken has one ovary and one inactive gonad, a remnant of early chicken development when sex genes haven't yet activated. A gonad can become an ovary, a testicle, or a combination of the two (ovotestis), but once those genes go the female route, that other gonad just sits there [source: Melina].
Now enter a cyst or tumor that damages the hen's ovary, and the gonad steps up to fill the sex-anatomy void. A gonad that develops into a testicle or an ovotestis instead of an ovary will start the release of androgens, a male sex hormone, and a sex change can result [source: Melina].
The typical hen-to-rooster transition begins with an end to egg-laying and progresses to behaviors and physical traits. A hen will start strutting and crowing, gain weight and grow the quintessential rooster wattles, dark feathers and cockscomb atop its head [source: Melina].
The result is essentially a sterile rooster. As far as the experts know, this change only happens to females; a rooster-to-hen conversion has never been documented [source: Melina]. div class="separator" style="clear: both; text-align: center;">
