Heterotrophs
Brown-Throated Sloths
The Brown-Throated Sloth (Bradypus variegatus) lives in the canopies of the Amazon Rainforest. They live in the canopies because of the leaves growing there. A sloth's diet consists of leaves. The leaves do not provide sloths with a lot of energy, thus causing the "lazy" behavior. These sloths have three "toes" or claws that are used to climb and hang from trees.
Picture (above): http://www.animalfactguide.com/animal-facts/brown-throated-three-toed-sloth/
Maues Marmoset
The Maues Marmoset (Mico mauesi) is a species of monkey that only inhabits part of the Amazon in Brazil. They depend on the trees for gums and saps, which is the staple of their diet. That is why these marmosets only live in the tropical rainforest. Their claws have adapted to gouge tree trunks for gums and saps.
Picture (above): https://www.newscientist.com/gallery/mammal-rush/
Poison Dart Frog
Poison Dart Frogs (Dendrobatidae) inhabit the rainforest floor in moist and shady areas. They mainly eat spiders and insects like termites. They only have one predator, Leimadophis epinephelus, a snake that has a resistance to the poison.
Picture (above): http://voices.nationalgeographic.com/2014/10/02/new-species-evolution-poison-frogs-peru-animals-science/
Jaguar
Jaguars (Panthera onca) live on the forest floor, but often enter the water for hunting purposes. Jaguars are carnivores, eating turtles, deer, fish, tapirs and many more. They use trees to mark their territory by scratching into the bark. Their fur is adapted to seem more camouflaged.
Picture (above): http://www.lovethesepics.com/2011/10/amazing-amazonia-amazon-rainforest-46-pics/
Piranhas
Piranhas (Characidae) can be found in the Amazon River. Piranhas are not picky about their diet, they will eat about anything from fish to cows. Seemingly vicious, their niche is to eliminate weak animals and keep populations in check. They have adapted razor sharp teeth to take down their prey.
Picture (above):http://bamazingwallpapers.blogspot.com/2015/11/amazon-piranha.html
Picture (left): http://www.facts-about.info/poison-dart-frog/