Mutations

Mutations are living organisms found on Earth by the delinquents that have been modified or disfigured by nuclear radiation.

Two Headed Deer
The Two-Headed Deer is an animal in The 100, seen in the episode Pilot It is the result from mutation after a century of radiation, cause it to have two heads. It is not hostile, and it is unknown if it uses both it's heads. It is seen in the title sequence of every episode so 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 less 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.

Luminos Butterflies
The luminos 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, other than the fact that they seem to travel in swarms.

River Snake
The River Snake is an animal in the show The 100. First shown in the episode PilotIt lurks in rivers and attacks whatever comes in with it. 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 too escape.

Luminous plants
Like the butterflies, some plants on Earth seem to glow in the dark. The plants that glow are both mossy tree bark and bushes. While they glow at night in the beginning episode(Pilot) They don't seem to be glowing in later episodes, indicating a possible inconsistency, or the possibility that they only glow some nights.