Mutations

A mutation is a genetic anomaly in a genome. In the aftermath of the Nuclear Apocalypse, prolonged exposure to abnormal conditions such as high radiation on Earth and the Ark resulted in many mutations in living organisms. The extent of the biological changes are yet unknown, except some discernible changes in the observable characteristics and much higher tolerance to radiation. All the mutations are presumably wiped out, due to Praimfaya.

Two-Headed Deer
The Two-headed deer is the result of mutation after almost a century of radiation, which caused it to have two heads. It is not hostile, and it is unknown if it uses both heads. It is seen in Pilot and in the title sequence of every episode thus far. From the side view, the deer looks like any other regular deer would have prior to the apocalypse. The body is the same in every way to a non-mutated deer; the only difference is the heads. One head is the primary head with most of the features, the other one is the secondary head because it is relatively smaller and shares fewer parts. The primary head has both antlers, one ear, a snout, one regular eye and barely any pink spots. The secondary head has no antlers, one ear, a deformed snout, one eye and many pink spots. Both heads share an eye in the middle.

Luminous Butterflies
The Luminous Butterflies are seen in the episode "Earth Skills". They look like ordinary butterflies, other than the fact that they seem to glow in the dark. The butterflies so far have only been seen during the day and do not appear hostile, rather acting like normal butterflies. They appear to group together and form roosts in trees, similar to migrating monarch butterflies.

Water Snakes
First shown in the episode "Pilot", river snakes lurk in rivers and attack whatever comes into the river. It is estimated to be 10 feet long and 2 feet wide. It slithers like a snake, but it also swims and bites like a piranha. It can cause minor injuries or fatal ones, depending on how quick their victim is to escape.

In Blood Must Have Blood (Part 2), a much larger version of the river snake is shown in the sea. It attacks a boat with Sky People and consumes two of them before leaving.

Two-Headed Horses
Two-headed horses are identical to regular horses, only they have two heads. They appear to have a similar mutation as the two-headed deer and potentially many other wildlife.

Humans
Humans can also be born with deformities due to radiation. Grounders call people with deformities "Frikdreina" (Trigedasleng). When a child is born with a deformity, Grounders usually leave the infant to die so that "the nature can reclaim them". The deformations can happen in many places, but have only been seen on the head and hand thus far. An example is Zoran, a boy with a disfigured face and Emori, a Grounder with a disfigured hand.

There was also a man with a severely mutated face seen in The 48. Octavia Blake said he was a monster, but Lincoln thought Octavia hallucinated the man.

All the "Frikdreina" were presumably wiped out, due to Praimfaya.

Pauna
Pauna is a giant gorilla. Lexa referred to Pauna as a Her. In the episode Survival of the Fittest, Pauna killed Quint and Major Byrne before chasing Lexa, Clarke, and Lexa's bodyguard into her feeding grounds amid the ruins of the National Zoo. Pauna killed Lexa's guard then Lexa and Clarke locked her in one of the rooms. Clarke later said the door would not hold for long after they had gotten away from Pauna. It is unknown if any other giant gorillas exist.

Luminous plants
Like the butterflies, some plants on Earth glow in the dark. The plants that glow in the dark are mainly mossy tree bark and bushes. While they glow at night in the first episode, they don't appear to glow in later episodes, indicating a possible inconsistency, or a cycle, meaning that they only glow some nights.

Jobi Nuts
In Day Trip, psychoactive nuts cause members of the 100 to exhibit unusual and/or irrational behavior and experience one or several psychedelic effects including hallucinations, euphoria (e.g. in the case of Monty), paranoia (e.g. in the case of Jasper). remorse (e.g. in the case of Bellamy), and flashbacks (e.g. in the case of Clarke). The psychedelic effects seem to appear within an hour or so and last a few hours. Lincoln explains that they are called "Jobi Nuts" and that they cause "visions" when they "go bad". While these nuts have not been established as a mutation, as of current day, no hallucinogenic nuts or fungi grow naturally in the area of the US where the 100 is settled, indicating either a mutation or a migration of natural plant species, both of which could be caused by nuclear radiation or a nuclear winter.


 * The following were affected by the Jobi Nuts:
 * Monty Green - Looking for the moon and eats a pine cone.
 * Jasper Jordan - Sees Grounders everywhere
 * Nathan Miller - Tripping out.
 * Bellamy Blake - Guilt over The Culling.
 * Clarke Griffin - Conversation with her dad.
 * Connor - Wanted to be the most beautiful broom in a broom closet of brooms.

Toxic Trees
In Bitter Harvest, Octavia comes into contact with trees oozing sap that burns her skin while she and Gavriel are hiding from Farm Station scouts. Later, Grounder villagers use the wood from these trees to set a trap for Skaikru, setting piles of the wood on fire with burning arrows to make a poison smoke that kills Monroe and another member of the group sent by Pike to clear the village.

The trees produce a yellow sap that burns the skin on contact. According to Pike, the ash from burning the wood from the trees rendered the land the Skaikru had intended to farm useless.

There are several trees today that have caustic sap and produce toxic smoke, including the Poisonwood Tree (Metopium toxiferum) and the Manchineel Tree (''Hippomane mancinella). ''Both can be found in the United States but they are usually found in more tropical areas. However, the trees seen in Bitter Harvest do not appear to be either one of these species, so it is likely that the trees encountered in the show are mutations.

Notes and Trivia

 * Bioluminescent butterflies in this series are different from fluorescence butterflies in the real world. Fluorescent butterflies have fluorescent markings on their wings and do not glow in complete darkness like bioluminescent butterflies would.
 * Emori and Sienna stated that Frikdreina (mutated humans) were not welcome in clans or villages.