The Season 5 premiere examines animals that have adapted in order to survive. Included: the moray eel that has evolved a second set of teeth to help swallow; the Komodo dragon that kills using bacteria; and sand tiger sharks who eat their siblings in the womb.

A look at beavers building emergency bunkers and spiders preparing traps to catch their next meal.

Sharks are one of the oldest species on the planet, so they have had plenty of time to evolve and develop some of the weirdest and most diverse skills and survival tactics. Discover the odd behaviors of sharks of all sizes, from the vicious hunters to the scrappy bottom-feeders, as they have never been seen before.

Parenthood practiced by naked mole rats and egrets.