Pikmin are a half-plant, half-animal lifeform that were discovered on an uncharted planet which Captain Olimar and his ship, the Dolphin, crash-landed on. Olimar named the Pikmin because of their resemblance to the pikpik carrots of his planet. Despite physical variations between the different species of Pikmin, all Pikmin have humanoid bodies with bulb-shaped heads, round eyes, a basic skeletal structure, three digits on each hand (which apparently act as roots) and long stems protruding from their heads with are tipped with leaves, buds or flowers. Pikmin are one inch tall and can evidently lift at least ten times their own body weight.
Pikmin are grown from seeds that come from 'onions' (so named by Olimar because they resembled the onions of his planet), the bulb-shaped organic nests of the Pikmin. The seeds are dispersed from the top of the onion when they absorb pellets dropped by flowers found around the planet or the bodies of fallen creatures the Pikmin have slain. When night falls the Pikmin themselves will return to the onion, which will lift off of the ground and hover over the planet until dawn to protect the Pikmin from predators. Pikmin will then emerge from the onion when called upon on the following day or if there are no Pikmin left in the onion it will produce a single Pikmin seed. Despite red, blue and yellow Pikmin living in onions, other variants don't seem to have onions and the white and purple Pikmin seem to be willing to live in the Hocotate Freight rocket in Pikmin 2.
Pikmin have three stages to their development cycle, each marked by the development of the plant at the tip of their stem. The leaf at the top of a Pikmin's stem will naturally grow into a bud and the bud will then grow into a five-leafed flower. The more developed a Pikmin is, the faster and stronger they are. Pikmin can also be found to develop faster when buried in the ground, but after taking damage during battle, flower Pikmin may change back into bud Pikmin and bud Pikmin back into leaf Pikmin. In Pikmin 1, flower Pikmin will also sometimes drop seeds in battle, suggesting that Pikmin may be capable of some degree of asexual reproduction.
Pikmin do not seem to eat or drink anything except for nectar, which allows them to mature one stage through their development cycle. It has been hypothesized that due to the Pikmins' lack of consumption of any food or drink they get all the nutrients they need from their onions. Pikmin also do not seem to directly breath but respire through the leaves, buds or flowers on their heads and release a ghost-like liquid or vapor the same color as themselves upon death which may be a kind of blood or hemolymph. When left idle Pikmin will also become paler than their normal color and the top of their stems will glow with their body color; the paleness may be caused by a natural response of their blood or hemolymph rushing away from the surface of their skin due to them no longer needing a strong blood flow as they become less active, while the glowing stem tips suggests some form of bioluminosity.
In Pikmin 1 only the red, blue and yellow Pikmin appeared, but Pikmin 2 introduced the purple Pikmin, white Pikmin and the rarer Bulbmin. Most Pikmin will develop white buds or flowers on the tip of their stems, but purple and white Pikmin develop purple-pink buds or flowers on the tip of their stems. Red, blue and yellow Pikmin are produced from onions, while purple and white Pikmin are produced by throwing other Pikmin into Candypop Buds found in caves, and Bulbmin can only be found wandering in caves. While it may hold no particular significance, a number of onions with colors corresponding to variants of Pikmin that have not been seen in-game appear at the end of Pikmin 1.
Red Pikmin have protrusive noses and are not damaged by fire. They are also the second strongest Pikmin in combat, next to the purple Pikmin.
Yellow Pikmin have very large ears, allowing them to soar higher when thrown. In Pikmin 1 they can pick up, carry and place bomb rocks, however they cannot pick up the much larger bomb rocks in Pikmin 2. In Pikmin 2 however, they are resistant to electricity.
Blue Pikmin have a single, large gill in the middle of their face which means that unlike other Pikmin they cannot drown. When left idle they will also rescue any nearby drowning Pikmin.
Purple Pikmin, first introduced in Pikmin 2, are much larger and heavier than other Pikmin and have a few thin hairs growing out of their head. The bulk of the Pikmin allows them to carry ten times their own body weight as well as instantly damaging and sometimes stunning any enemy they are thrown onto. They do move much slower than all other Pikmin though.
Pikmin 2 also introduced White Pikmin which are smaller than other Pikmin and have large red eyes. They are faster than other Pikmin, can dig up buried treasure, cannot be poisoned and damage enemies when eaten by them.
A very uncommon variant of Pikmin was also first seen in Pikmin 2. These Bulbin are actually parasitic Pikmin who have taken over juvenile Bulborbs. They are resistant to all hazards that kill other Pikmin but are unable to leave caves after they are found. Interestingly, when left idle, their leaves glow green.
Mushroom Pikmin (sometimes called Zombie Pikmin or Toadmin) are not actually a species of Pikmin but rather a form that Pikmin take on when they are under the control of the Puffstool that appears in Pikmin 1. They are purple in color, with white pupil-less eyes and a brown mushroom at the tip of their stem. Mushroom Pikmin will attack Olimar and his Pikmin but they will turn back into their original form when Olimar either shakes them off, leaves them alone for a while or the Puffstool is defeated.
Introduced in Pikmin 3, these Pikmin are essentially anthropomorphic rocks with arms, legs, and a flower protruding from their head. They can be used to break through objects too hard for other Pikmin to significantly damage and basically turn into walking candles when they come in contact with fire. However, they cannot hold onto enemies or objects and thus, once thrown at an object or enemy, their attack pattern consists of running into their target over and over again.
Introduced in Pikmin 3, these Pikmin can fly over terrain such as water. They can carry items in the air and attack airborne enemies with ease.
When Olimar crash-landed on the planet of the Pikmin they mysteriously instantly accepted him as a leader figure, following his every command and following him when he whistled. In Pikmin 2, when Olimar returned they not only immediately accepted him as a leader again but also treated his co-worker Louie in the same manner and later in the game the Hocotate Freight President. The Pikmins' tendency to obey the human characters of the game may be due to the fact that in their spacesuits they resemble Pikmin themselves. This seems to be evidenced by the fact that when idle the Pikmin will also imitate the human leading them.
Pikmin also appear to be highly social creatures, interacting, playing and grooming each other while idle. Pikmin in larger groups will also hum or chant tunes in synchronization. However, without a leader the Pikmin seem to be relatively defenseless, and were originally found with their onions in a hibernation-like state and seeming even to do a quite poor attempt of defending themselves when idle and being killed by another creature.
- In Pikmin 2, if 20 Pikmin of each different color are called into one group they will start humming a portion of Ai No Uta, a popular song in Japan used to advertise Pikmin 1.
- A glitch exists in Pikmin 1 where if the Puffstool tries to take control of the Pikmin at the same time they fall to the floor, they will become Mushroom Pikmin but appear as though they are idle and will still be under Olimar's control. This can also be exploited in a way that they can be called back to Olimar's side but this can be difficult to accomplish.