Zach Varmitech spies on the Wild Kratts while they're traveling in the Amazon rainforest. They explain that the rainforest has the highest biodiversity out of any land habitat: it's home to 10% of Earth's creatures. They define it as the amount of plants and animals in a region.
A minituarized Martin has been following Hero the Salmon on her Salmon run. They both swim into Aviva, who is standing in the river. Aviva and Martin follow Hero on part of her journey, when they get to one of Hero's obstacles, a waterfall.