Andrea Schlake volunteers at an animal sanctuary when a chimpanzee escapes its enclosure and chases her down; a great white shark knocks surfer Todd Endris off his board and attacks him.

A timber rattlesnake strikes; an alligator bites down on woman's arm and pulls her underwater.

Grizzly bear charges elk hunter and his son-in-law; bull shark attacks spearfisher Anthony Segrich.

A polar bear chases down Erin Greene as she walks home from a Halloween party in a small arctic town; a bull shark attacks triathlete Chuck Anderson in the Gulf of Mexico, biting his arm and pulling him to the ocean floor.

Diver Tim Saxon films underwater at the Great Barrier Reef and gets stung by an Irukandji jellyfish, one of the world's most venomous animals; a grizzly bear attacks forester George Knoll in the remote Great Bear Rainforest.

A black bear charges Joe Azzouggagh and his German shepherd, Ace, deep in the Ontario wilderness; single father Andrew Dickehage, forced to walk six miles along a rural road at night, comes under attack from unseen predators.