In the tropics, species evolve twice as fast as those in more temperate climates. Warmer temperatures speed up chemical reactions, introducing mutations at a faster rate and generating novel characteristics. It's, therefore, unsurprising that the tropical rainforest is home to some of the quirkiest creatures on Earth.
1. Mandrill
The mandrill is a magnet for superlatives: It's the largest of all monkeys and one of the most colorful mammals. They're known for the blue and red markings lining their snout and their multi-colored behinds, which become brighter when they're excited. Despite their dynamic exterior, mandrills are shy and run away from researchers, making them tricky to study in the wild. Found only in the rainforests of equatorial Africa, the region's deforestation and poaching have earned them a spot on IUCN's red list of vulnerable species.