Castilho placed wild animals in homes to explore the complex perceptions people have toward themselves as humans and as animals.
"What interested me was precisely to bring the animal -- in (this) case a wild animal -- into a domestic environment where, potentially, we humans felt more comfortable," Castilho said. "I wanted to shuffle positions and boundaries that sometimes are too rigid."
Castilho says his photos are an exploration into age-old issues pertaining to animals and animality, citing philosophical and literary thinkers Franz Kafka, Gilles Deleuze and J.M. Coetzee.
"We say, 'This is the place of men, that is the place of animals.' ... But why is that?" Castilho said. "Are not we also animals? What brings us closer? What of them exists in us?"
All of the animals photographed were under the supervision of nongovernmental organizations in Brazil that had taken them in for various reasons, such as prior mistreatment. Castilho said many of the animals cannot live in their natural habitats any longer, as they were either born in captivity or are debilitated.
Each photo was shot under natural light, and Castilho observed that the wild animals were "more silent and unpredictable" compared to domestic animals.
"It is a difficult job because it is done with the greatest respect possible," Castilho said. "It is difficult to find animals that are docile enough to keep everyone -- men and animals -- safe."
Castilho's photo series encompasses a diverse range of subjects, leaving viewers to feel as though their eyes are roaming around an actual zoo.
"I think the photo of the puma (is) a special one because it's a really fascinating animal," Castilho said. "Paradoxically, it was one of the most dangerous I photographed. It is strange to be face to face with an animal that can potentially kill you."
The colors and composition of each photo are just as unpredictable as the animals themselves.
While the dark-gray and brown snake is clearly recognizable as it contrasts with the bright blues and pinks surrounding it, the puma is bathed in the orange and brown hues of the room it is laying in, making it appear as if the animal is not even there.
"The animal carries much of the human mystery," Castilho said.