19. Water Bear



This is no bear, it's actually almost microscopic, getting to a length of less than 1 mm. However, these little creatures are TOUGH. They can survive temperatures that range from absolute zero (-457℉) up to 357℉, withstand radiation 1000 times more powerful than other animals can take, and even come back to life after being dried out for 10 years. They are the first animals known to be able to survive the vacuum of space.

21. Nudibranch



Also known as sea slugs, there are over 3000 types of nudibranchs and they include some of the craziest looking ocean creatures.

23. Ribbon Eel



The ribbon eel may look pretty ordinary, but its one of the only species of the planet to be able to change sexes. They start out males, all of them, but as soon as they mature, many will start developing female parts.