Metroid (Species)

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Metroids are not pets. Metroids are not for target practice.

Space Pirate logs from Metroid Prime 2: Echoes

Metroids are the titular creatures of the Metroid series. Created by the ancient Chozo race, they first became known to the universe at large when Space Pirates discovered them on their homeworld of SR388, and promptly decided to use them as bioweapons. Metroids feed on the "life energy" of their prey in a manner similar to the way a leech drains a host organism's blood. Unlike leeches, Metroids leave all of their prey's blood and internal organs intact, yet lacking the energy necessary to sustain life.[1] It is unknown exactly how the Metroid extracts this "life energy" or what, in fact, said life energy consists of.

The Metroids were long rumored to be created by an ancient race, though their motive for doing so remained a mystery to the rest of the universe. Eventually, it came to light that the Chozo were the ones who genetically engineered the Metroids, in order to prevent the spread of the more dangerous X Parasites. Appropriately, the word "Metroid" in the Chozo language roughly translates to "Ultimate Warrior".

Physiology and morphologyEdit

Original Metroid

Possibly the first Metroid ever created by the Chozo.

The most commonly seen form of Metroid consists of a thick, round, gelatinous membrane resembling a jellyfish's hood, typically ranging from blue to green in color (sometimes red if exposed to environmental conditions like those on Aether). Within this membrane can be seen four red, spherical organs resembling nuclei, closely arranged so only three can be seen from most angles - their function is unknown, though the neuron-like connections growing between and out from them could mean they comprise the Metroid's brain. The Metroid's fleshy, leech-like mouth lies underneath all of this, and features two pairs of mandibles: the larger pair for gripping their prey, and the smaller for siphoning out its life energy. Metroids appear capable of directly sensing the life energy of their prey, despite having no recognizable sensory organs. An even greater mystery of their biology is their ability to perpetually float in midair, despite lacking any visible means of propulsion.

10 copy

A Metroid dividing due to heavy exposure to beta radiation.

Metroids are vicious creatures with no natural predators, being at the top of the food chain on SR388. They appear to be quite intelligent - for example, when a Metroid is released into a room containing both Space Pirates and Samus Aran, it will recognize Samus Aran as the greater threat and attack (unless the Space Pirate is closer). Once attached to their prey, Metroids are nearly impossible to dislodge and will quickly drain their victim's life force completely, often killing it in seconds. Using Morph Ball Bombs is the only known way of dislodging an attached Metroid; consequently, Samus is one of the only two beings capable of surviving Metroid attacks, the other survivor being Mother Brain by using an unknown 'resurrection' ability.

Metroids have a voracious appetite, and will feed on any and all living creatures they encounter, with the exception of their own species. This threat is compounded not only by their invulnerability to most forms of weaponry, but also their ability to asexually reproduce via division when exposed to extremely high amounts of beta radiation - in a process much like a cell undergoing mitosis. This latter trait seems to be restricted to the Infant and Larval stages of a Metroid. The only major vulnerability Metroids possess is to extremely cold temperatures: They tend to become sluggish in frigid conditions, and their membranes are easily (if briefly) frozen solid, allowing the creatures to be shattered and killed by concussive weaponry such as Missiles and Super Missiles. Power Bombs can also sometimes harm them, though their level of effectiveness varies widely. In Corruption, Samus was also able to use the X-Ray Visor to lock onto a Metroid's nuclei, allowing her to use the high-frequency Nova Beam to penetrate the protective membrane and directly strike the nuclei within, instantly dispatching the creature.


A Metroid Egg.

Metroids naturally hatch from round eggs, beginning life as small, simple infants before maturing into their most commonly seen form. However, this form is only the larval stage of a Metroid's natural life cycle: When living in its natural environment on SR388 (or a simulation thereof), a normal Metroid can further metamorphose into four additional stages - Alpha, Gamma, Zeta and Omega. Each metamorphosis drastically restructures the Metroid's morphology, with the Alpha and Beta stages resembling a floating insect or crustacean, while the latter stages transform the Metroid into a more reptilian, therapod-like configuration. As they grow, Metroids also gain the ability to project bolts of static electricity or spit toxic saliva at their prey. Each stage also reduces its weakness to cold, as it gradually develops a thick, hard carapace that reduces (but never fully eliminates) the exposure of its vulnerable membrane.

A final, eighth stage also exists, and is the only stage capable of producing eggs - however, this stage is extremely rare, and the chances of a Metroid having the genetic potential to reach it are infinitesimal.

Space Pirate Data states that Metroids mutate differently depending on what planet they are exposed to.[2] Metroids cannot mutate into their natural advanced stages seen in Metroid II and Fusion unless they are on SR388 or on a perfect replica of the planet. However, when mutated by Phazon, Metroids are prone to mutating into other, unique stages, like the Hunter Metroid, Metroid Hatcher and Hopping Metroid, each one granting unique qualities such as the ability to phase through walls. The most severe example of this is the Metroid Prime; after 50 years of feeding on Phazon, it metamorphosed into a gigantic, multilegged abomination with numerous weapons built into its black exoskeleton.

Metroid egg

Metroid Eggs on the Pirate homeworld.

The Metroids live on a mysterious energy that they drain from their victims. What this energy is remains unknown; the victim loses no bodily fluids but perishes nonetheless. As of Metroid Prime, this energy is referred to as "life energy". Metroids are stated to be energy-based organisms and thus increase in mass as they drain energy. Metroids can also feed off the energy used by Samus's Power Suit, which will protect Samus herself as long as it is active. However, were her suit to lose all of its energy, Samus would be rendered vulnerable to the Metroids. This almost happens to her in Other M; as she is about to kill a Baby Metroid she encounters, Adam Malkovich fires at her with a Freeze Gun. The shot, combined with her emotional duress at the time (the Metroid here reminded her of the recently-deceased baby) causes her to lose her Power Suit. Adam shoots the Metroid and freezes it before it can attack Samus.

In addition to draining life energy from victims, Metroids can heal other life forms by transferring stored life energy into them as demonstrated by the baby in Super Metroid. This stored energy can also be drained from the Metroid, allowing it to be used as a living rechargeable power cell. However, a scan of a Tallon Metroid in Metroid Prime 2: Echoes reveals that repeated energy drains can cause cellular breakdown to occur in Metroids.

It is also revealed through Pirate Homeworld scans in Corruption that Metroids have a sensitivity to certain sonic frequencies, which the Pirates exploited to subdue several Phazon Metroids in the Metroid Processing chamber, using Metroid tank barriers.

Metroids! This species of energy draining, unicellular aliens can be frozen, then shattered with a blast from one of my missiles, but when they are in their normal, pulsating state, they can absorb my attack. They're treacherous!

—- Samus Aran, Super Metroid's Samus Aran Profile


Official dataEdit

Metroid manualEdit

"This protoplasm in suspended animation was discovered on the planet SR388. It clings onto Samus' body and sucks his[3] energy. It can't be destroyed directly with the normal beam. Freeze it with the ice beam, and then fire 5 missile blasts at it."

Official Nintendo Player's GuideEdit

"This is a mysterious life form which was discovered on the planet SR388. It sticks to Samus’ body and sucks out her energy."

Metroid II manualEdit

"This is their first shape after hatching from eggs. They will cling to any creature that they can find, drawing its victim's life energy away."

Super Metroid manualEdit

"It is said that Metroids are life forms created by an ancient civilization. Metroids engulf living creatures and absorb their energy. They are very intelligent and quick to reproduce."

Super Metroid Nintendo Player's GuideEdit

Metroid regular

A cloned Metroid in Super Metroid.

"Freeze them, then blast them with Super Missiles."

Official Metroid Fusion websiteEdit

"These energy-based creatures have the ability to absorb the life force from any living thing. As the natural predator of X-Parasites, however, the Metroid may now be the key to Samus's survival."

An energy-based life-form with a translucent, spherical upper body. Claw-like spikes protrude from the lower-half of the creature, which it uses to latch onto its prey."

Metroid: Zero Mission manualEdit

"Metroids are the floating organisms discovered on planet SR388. These fearsome predators latch onto other organisms and leech the life energy out of their prey."

Official Metroid: Zero Mission websiteEdit

"Extremely dangerous! Gelatinous exterior of Metroid makes it impervious to beam weapons. Metroids can only be destroyed by Missiles while frozen. Large claws grip prey while smaller front fangs drain its life force. Transform to Morph Ball and use Bombs to escape grip. DANGER LEVEL: HIGH"

  • "Gelatinous exterior"
  • "Multiple brain stems"
  • "Gripping claws" (Outer)
  • "Energy-sapping fangs" (Inner)

Logbook entryEdit

Metroid scanpic Metroid scanpic 2
Metroid scanpic 3 Metroid scanpic 4


Metroid Prime

Temporary scan

Morphology: Metroid
Energy-based parasitic predator.

Logbook entry

The dominant species of planet SR388, Metroids are energy-based parasitic predators. A Metroid will latch onto its prey and drain energy, growing larger as it does. The only way to shake an attached Metroid is to enter Morph Ball mode and lay a Bomb.

Official Metroid Prime WebsiteEdit

"Metroids are highly dangerous parasites averse to cold temperatures. The dominant species of planet SR388, Metroids can suck the life force out of living things. A Metroid will latch onto its prey and drain energy, growing larger as it does.

Metroid Prime Pinball manualEdit

"An energy based, highly dangerous parasite."

Smash TipsEdit

"These alien creatures float around and then try to clamp down on you with their sharp fangs. Quickly struggle to break free from their grasp."

Smash Tour (SSB4 Official Game Guide)Edit

"Lasts 5 turns or until a player bumps into it two times"

"Bumping into this enemy costs you several stat boosts! Reclaim lost stat boosts by bumping ino it a second time."

Appearances in other mediaEdit

Mt hero2

Metroids appear in Nintendo Comics System's The Coming of a Hero, Deceít Du Jour, and Captain N: The Game Master's Breakout

"What's the matter? All I said was that Komaytos look like little Metr—"

Non-canon warning: This article or section contains information that may not be considered an official part of the Metroid series in the overall storyline by Nintendo.
  • Metroids appear in the Kid Icarus franchise, under the name Komayto, which is stated in the instruction manual to have come from another planet. This creature can be found flying around Skyworld in packs. Kid Icarus was also created using the Metroid game engine. During the game Kid Icarus: Uprising, the main character Pit states himself that "Komaytos kind of look like little Metroids" before being hushed by Viridi.
  • A Metroid is a collectible treasure in Wario Land II. They are also often in 9-Volt's microgames in the WarioWare series, such as WarioWare, Inc.: Mega Microgame$!, WarioWare, Inc.: Mega Party Game$!, WarioWare: Touched! and WarioWare: Twisted!.
  • Metroids made an appearance in Kirby's Dream Land 3 for the SNES. If Kirby freezes all the Metroids in the level, Samus removes her helmet and gives Kirby a Heart Star.
  • Metroids wander onto stages randomly in Metroid Prime Pinball and also have their own minigame, Metroid Mania.
  • In Metroid Prime 3: Corruption, a Metroid is used on the tab for the creatures section of the Logbook. Interesting to note is that the Metroid depicted here has six nuclei, five encircling the top of a larger, centralized nuclei.
  • The Baby from Metroid II: Return of Samus and Super Metroid appears as an item in the Nintendo DS game Animal Crossing: Wild World. It appears in its signature capsule, and if tapped will play a few seconds of the Super Metroid title screen theme. It is a rare item that is acquired randomly by shooting down Gulliver. The item also appears in Animal Crossing: City Folk, but cannot be transferred through the ingame catalogue due to the item's rarity. It acts the same way as before and is obtained in the same manner as well; it will play the entire Super Metroid theme this time however. The same item appears once again in Animal Crossing: New Leaf, but it is not obtained through the same method as the two previous games. Instead, it is randomly acquired through fortune cookies, which the player can buy using two of the 3DS's Play Coins. This version also plays only a few seconds of the title theme.
  • In Tetris DS, there is a single player game mode called Catch Mode where players catch Tetraminos (blocks) in order to create a 4X4 square and detonating it to make the cluster smaller. The Brinstar theme plays during this and encapsulated Metroids (in capsules similar to the Metroid hatchling's) fall down. If touched, the energy meter will go down and the cluster becomes smaller.
  • A Metroid can be seen on Nintendo Monopoly representing St. James Place for $180.
  • A Metroid is shown in a capsule in Singularity along with the message "Mother my brain hurts".
  • A Metroid is seen in a tank in Starcraft 2: Wings of Liberty in the secret Mission "Piercing the Shroud." It is very similar to that of the baby.

Super Smash Bros SeriesEdit

  • Metroids appear in a minor reference in Super Smash Bros., in Super Smash Bros. Melee as a trophy as well as the Baby being seen in the opening cutscene, and in Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS and Wii U as an Assist Trophy that will latch onto opponents and "drain" them of energy (what they actually do is increase the victim's damage, but can still sap health if a stamina match is being played). It can be shaken off, which will cause it to try and seek another victim. It can phase through platforms similar to a Phazon Metroid. Using Up-Special moves while the Metroid is latched on to a character cancels the move after the few starting frames; this can be done multiple times in a row. This allows some characters to stay in the air for quite a while. Interestingly, the model of a larval Metroid used in-game for the Nintendo 3DS and Wii U exhibits unnaturally large inner-fangs; in fact, they appear to be larger than the outer ones. In Melee, the intro scene from Super Metroid is reflected off of the trophy, with the infant missing from the scene.

Super Smash Bros.Edit

Metroids are briefly mentioned in her "Characters" bio in the "Data" section of SSB. Her bio says that Samus "... pursues the airborne life form, Metroid, throughout the whole universe."

Super Smash Bros. MeleeEdit

Fig 02 240

Super Smash Bros. Melee website.

"A parasitic life form that can absorb all types of energy, Metroids have strong resistance to most conventional weaponry. To defeat them, Samus Aran had to freeze them with Ice Beam shots and then blast them with missiles. Mochtroids, which look like Metroids, are weaker, with fewer internal nuclei."

(Metroid 08/89).

Super Smash Bros. BrawlEdit

"A bioengineered life-form found on planet SR388. Metroids attach to organisms and drain life energy. The Galactic Federation commissions Samus to eliminate them, but Space Pirates try to harness their power. One of the few ways Samus can kill Metroids is by shooting them with the Ice Beam and then shattering them with missiles. The Metroid's cry is chilling and indescribable."

Metroid (1987)
Metroid II: Return of Samus (1991)

Smash Bros. DOJO!! data on the Assist TrophyEdit

"Like the name says, this Assist Trophy is from the game Metroid. It's an artificial life-form that absorbs all kinds of energy.

In our game, it also attaches to the head and starts to drain its victim. Since it will increase your damage, try to shake it loose."

Super Smash Bros. for Nintendo 3DS and Wii UEdit

Metroid SSB4
Super Smash Bros. for Nintendo 3DS and Wii U TrophyEdit
"First discovered on planet SR388, this floating life-form grows by absorbing the energy around it. It is incredibly durable but extremely weak to cold. In Smash Bros., a Metroid will grab a rival by the head and drain energy. If you get grabbed, shake it off by pressing left and right!"
"Mysterious floating life-forms, discovered on the planet SR388, that absorb energy from other living beings. They're tough, except when they're cold. In this game, they'll try to attach themselves to fighters' heads and drain their energy. Press all the buttons you can to shake them off!"

Nintendo LandEdit

Metroids appear as robots. They can suck out the Mii's energy but they also like to drop Miis in the Lava on the volcano map. Metroids must be frozen with the Ice Charge before shooting their core to kill them, reminiscent of how they are killed in the official Metroid games. This game also implies that the Chozo went extinct because they lost control of the Metroids.

Non-canon warning: Non-canonical information ends here.


Kiyotake: There was one more staff member, and the two of us decided on it. We attached "android" to the "metro subway" and that's how we got "Metroid". [4]


Original Metroid Origins

The original origin of the Metroids.

  • The unidentified energy that Metroids feed off of has never been fully disclosed in the games.
  • Chronologically, Samus' first encounter with Metroids occurred in Tourian; ironically, the last of the species would later become extinct there.
  • While the Metroids' purpose was stated in the manual for Metroid Fusion to be the eradication of the X Parasites, the backstory in the PAL Super Metroid guide tells a different story. It states that the Metroids may have been given their ability to transfer energy into organisms by their creators with the hope that the creatures could use it to benefit humanity.
  • The eggs which can be found on the Pirate Homeworld in the room Metroid Processing are in a tank with large metal 'hands' clasping them. This is similar to the scene in Jurassic Park, where dinosaur eggs are being produced and hatched with a similar metal claw.
  • Bioforms that are killed by Metroids turn into husks with characteristics that, for unknown reasons, vary during time. Some turn into an extremely fragile brown or colorless husk that crumbles into dust on contact, while others become hardened corpses that cannot crumble.
  • Metroids have never been successfully contained without them somehow breaking free, either through their own means or through the help of another being, intentional or not.
  • Additionally, it is arguable that Mother Brain's telepathic powers were unable to maintain complete dominance over Metroids, as a few varied incidents in the past have provided some skepticism to the level of control Mother Brain has had on the Metroids.
  • There have been no known cases of intraspecific competition between Metroids for right to feed. In occasions where several Metroids are in the presence of a potential prey, they will take turns attacking the victim (in the Prime series and Zero Mission gameplay), or will group together to feed on a victim simultaneously (as seen in Metroid II, Super Metroid and during a cutscene in Zero Mission).
  • Dark Tallon Metroids were seen piling Pirate Troopers together on Dark Aether, seemingly conserving their food for later group feedings. However, this behavior is most likely non-existent in other Metroid variants, as these Dark Tallon Metroids are actually controlled by the sentient race known as the Ing. Interestingly, this also means that the Ing were capable of overcoming their possessed victims' insatiable hunger and no longer devour their prey quickly and completely.
  • A Metroid project "Dread" is mentioned in a scan in Metroid Processing detailing failed Pirate plans to use Metroids as a battery source, although many fans assumed it was a reference to Metroid Dread, a supposedly lost Metroid game.
  • The full limitations of Metroid behavior has not fully been explored. However, it may extend beyond the simple feeding instinct, as demonstrated by the baby in Super Metroid. Technically, it had grown beyond the imprinting of Samus as its mother, yet it still recognized her and restrained itself, even going so far as to save her from Mother Brain and transfer energy and a new weapon back to her.
  • Ironically, the Galactic Federation has been successful in many elements concerning the Metroids, many of which the Space Pirates ultimately failed to achieve despite years of trial and error. The ringleaders had found an extremely reliable way of controlling Metroids in the form of the humanoid MB. They had also successfully rid the creatures of their greatest vulnerability: cold. Finally, the Federation was able to give the Metroids access to their natural mutations, despite the creatures being located outside of their homeworld, SR388.
  • The Metroids have actually been able to nullify their weakness to cold on one occasion, long before the Federation did. This was seen in specific Fission Metroid variants and Metroid Prime's core form during Samus's mission on Tallon IV. However, this invulnerability was unintentional, as these two Metroid species had achieved this ability through an unpredictable series of mutations caused by Phazon.
  • During the events of Super Metroid, the Space Pirates allegedly tried different ways to clone Metroids other than using Beta-Rays, resulting in the weaker variant seen in Maridia, Mochtroids.
  • Metroids seem to not have the need to breathe oxygen. This is seen when entering the G.F.S. Valhalla; while exploring the destroyed ship, Metroids are seen outside of the ship and wandering about in space. Also, an Omega Metroid was in the hanger bay of the Biologic Space Laboratories research station, as the door was broken showing the vacuum of space, possibly having the room decompressing.
  • In Metroid Prime and Metroid Prime 2: Echoes, Metroids who have broken free from their containment tubes will engage in combat with the Pirates and vice versa. However, on the Pirate Homeworld in Metroid Prime 3: Corruption, both sides will ignore each other and assault Samus in tandem. A logical explanation would be that both sides, being corrupted by Phazon, no longer see each other as adversaries (this has been noted in Pirate research experiment reports found by Samus in Metroid Prime) or that both species are forced by Dark Samus to work as a group. This could also be due to a programming error, as both creatures never appear in the same room outside of containment unless Samus trips the alarm and enters a Metroid-infested room, forcing the Pirates to appear in it.
  • In Metroid Prime and Metroid Prime 2: Echoes, when a Metroid collides with Phazon or an open door, it will explode.
  • Ironically, the Blue X of Metroid Fusion attempted to counteract against Samus due to her Metroid cells and her weakness to cold. It is doubtful Cold X existed back on SR388 due to the planet's lack of a cold climate. If they had existed, it is possible the Blue X would have had an advantage over the Metroids on SR388.
  • In early encounters with the SA-X, the imitation would attempt to kill Samus by using the traditional tactic used to kill larval Metroids (freezing her in place with the Ice Beam, then shooting a Super Missile at her).
  • Some Space Pirates are known to have treated Metroids as pets. Although High Command strictly forbids this, some Metroids can be scanned with evidence of being recently fed with Space Pirate rations and pet treats. This caused the Metroids in question to suffer food poisoning, and occasionally became frenzied creatures.
  • Metroids are the Metroid series equivalent to the titular Aliens of the Alien series, featuring a life cycle, a Queen producing eggs and being a menace to the female protagonist.
    • Coincidentally, the spinoff prequel film Prometheus, created well after the Metroid franchise, implies that the Xenomorphs were created by an advanced alien race, the Engineers, for use as a bioweapon, similar to the Chozo developing the Metroids to stop the spread of the X Parasites.
  • A Metroid appears in the Piercing the Shroud level of Starcraft II: Wings of Liberty, in a capsule similar to the baby's.
  • Metroid Other M Metroid Art 94

    Note the four nuclei visible within the blue inset.

  • The background of Metroid Prime Pinball 's Wireless Mission mode features a Metroid with many more, smaller nuclei and a jagged shell.
  • When reading the temporary scan of a creature in Corruption, a pair of Metroids are seen to either side of the scan text. The nuclei of the two Metroids are placed side to side and are connected by lines to the bottom of their membrane.
  • NES Remix includes a Metroid Miiverse stamp.
  • Phazon was originally explained as the remaining energy from the Metroids Samus exterminated on Zebes, undergoing fractal cloning.[1]
  • Despite their weakness to cold temperatures, Metroids can survive in space, which constantly fluctuates between extreme heat and extreme cold.


For official artwork, see Metroids' Gallery.

Notes and ReferencesEdit

  1. ^ Metroid Prime Pirate Data "Metroid Morphology" from Phendrana Drifts
  2. ^ While in the Metroid Processing area of Metroid Prime 3, when you scan the dissected Metroids you read "Observations on Metroids native to different planets display subtle variations in biological processes." Such as in this video. When scanning a Metroid in a glass tube you read "Our Homeworld's unique atmosphere has resulted in various unique physiological mutations." Such as in this video.
  3. ^ The English manual for Metroid deliberately referred to Samus as a male, not a female
  4. ^ Famicom Disk System: The More You Play It, the More You'll Want to Play! The Metroid Database. Retrieved on 2011-06-15.

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