The first sense to evolve in the first animals was chemoreception. It means being able to detect chemicals in the animal's environment. This helps animals find prey and mates, and to sense predators from a distance. Some of the animals featured in this episode are: sharks, black widow spiders, snakes, rats, bears, and turkey vultures. This segment to will touch on the many uses for smell for may different animals in order to survive and thrive.

pt. 1. Sharks - Smelling Prowess -- pt. 2. Black Widow Spiders - Deathly Chemical Communication -- pt. 3. Snakes - Forked Tongues and Noses that Sense Heat -- pt. 4. Rats - Resilience through Smell -- pt. 5. Bears - A Bear Needs to Eat! -- pt. 6. Turkey Vultures - The Best Avian Sniffer.