After almost five years of exploring the wilderness of the southern Brazilian Atlantic Rainforest, a group of researchers has discovered new species of tiny and brightly colored frog.

The unique climate and isolation of the region has produced species of Brachycephalus, each species being remarkably endemic and highly vulnerable to extinction. Because many of the species are brightly colored, it is possible that these frogs have a very potent neurotoxin known as tetrodotoxin in their skin.

"Following extensive fieldwork in montane areas of the southern portion of the Atlantic Rainforest, in this study we describe seven new species of Brachycephalus from the states of Paraná and Santa Catarina, southern Brazil," wrote study researcher Marcio Pie, from the Universidade Federal do Paraná, and colleagues in their report published in PeerJ. "These species can be distinguished from one another based on coloration and the level of rugosity of the skin in different parts of their body."

Measuring no longer than 0.4 inches, these frogs are among the smallest vertebrates that live on land and their small size has led to a number of changes in the structure of their body such as the reduction of the number of their toes and fingers. The miniature frog's size may be remarkably but there are other tiny animals in the world.

Bumblebee bat

The Bumblebee bat is considered the world's smallest bat. Weighing less than a dime's weight, it could even be the world's smallest mammal. The tiny bat lives in Thailand, where they thrive in lime caves.

Western Pygmy Blue Butterfly

The Western Pygmy Blue is the world's smallest butterfly having a wingspan of only half an inch. The butterflies can be found in their host plants such as the salt brush and pigweed.

Bee Hummingbird

Weighing nearly the same as the weight of a dime, the bee hummingbird can flap its wings over a hundred times in a minute. The tiny bird lays the smallest eggs in the world.

Mouse lemurs

Mouse lemurs are so small they can be held in the palm of the hands. Experts, however, advise against doing so because they can be fierce. The tiniest species of this animal is the Madame Berthe's mouse lemur which only weighs about an ounce.

Dwarf Lantern Shark

Measuring only about 7 inches, the bioluminescent shark is no bigger than the phone making it the smallest shark in the world.

Etruscan shrew

The Etruscan shrew, the smallest mammal by mass, is characterized by very fast heart beating rate. Their heart beats 25 times per second.