Metroid (species)

Metroids are artificial organisms in the video game series of the same name, discovered on the planet SR388 years after they were created by the Chozo, and promptly used as a bioweapon by the Space Pirates. Metroids feed on the "life energy" of their prey in a manner similar to the way a leech drains a host organism's blood, however they leave all of the prey's blood and internal organs intact, feeding just off of their life source.

According to the Super Metroid instruction manual, the Metroids were rumored to be created by an ancient race. The Chozo, revealed in Metroid Fusion's manual, genetically engineered the Metroids to prevent the spreading of the dangerous X Parasite life-forms. This is expanded upon in chapter four of the Metroid manga. The name "Metroid" in the Chozo language means "Ultimate Warrior".

Physiology and morphology
The body of a Metroid consists of a thick gelatinous membrane (resembling that of a jellyfish) and contains a set of four (Tallon Metroids) to three (Phazon Metroids) red, raspberry-shaped, quadripartite/tripartite nuclei. They have two pairs of mandibles, one for gripping their prey and the other for extracting its life energy. Metroids appear to be able to directly sense the life energy of their prey, as they have no visible sensory organs. In the early stages of their development, Metroids hover in the air. Metroid Prime 2: Echoes explains that they defy gravity by using kinetic energy that was stored in their body. These larval Metroids are the ones most often encountered in the Metroid games. Traditionally, larval Metroids are transparent or translucent with hints of certain colours (green, red, blue, etc.).

Metroids are vicious creatures with no natural predators. However they appear to be quite intelligent; for example, when a Metroid is released into a room containing both Space Pirates and Samus, they will attack the Space Pirates first as they are the easier prey. Once attached to their prey, they are very difficult to dislodge and will quickly drain their victim's life force completely, killing it. Morph Ball bombs are the only known way of dislodging Metroids and Samus is, as a result, the only person known to have survived a Metroid attack. They are known to finish off their victims in a matter of seconds. Metroids have an endless appetite and will feed on any and all living creatures they come across, with the exception of their own species. This immense threat is compounded by their invulnerability to most forms of weaponry. They have only one real weakness: an extreme sensitivity to cold temperatures. Once their membrane is frozen, it can be shattered by concussive weaponry (such as Missiles), killing the Metroid. In Metroid Prime, they can be killed by any weapon and, if Samus has enough energy, she can even let them drain her until they explode, as they will first drain her suit's energy shielding before gaining access to her life-force. However, once they take all her energy, she will be vulnerable to their attacks. One should note that these Metroids are of a unique and weaker sub-species known as Tallon Metroids. Normal Metroids also drain Samus's suit energy until it runs out, but they do not explode from this.

In their natural life cycle (as seen in Metroid II: Return of Samus and in the end of Metroid Fusion), Metroids gradually metamorphose into a somewhat reptilian form; as they change, they eventually replace their gelatinous membrane with a hard organic shell and grow a head and a set of limbs. The shell removes their weakness to cold temperatures, but most forms retain a section of weak, uncovered membrane which is vulnerable to attack. The only known forms with complete shells are the Queen Metroid and Metroid Prime. The egg-laying Queen Metroid appears to be the only form in which Metroids can naturally reproduce. As they grow, Metroids also gain the ability to project bolts of static electricity or spit toxic saliva as attacks.

In Metroid Prime 3: Corruption, it's noted by the Space Pirates that Metroids evolve differently depending on what planet they are exposed to, such as the Hunter Metroids encountered on Tallon IV (Metroid Prime). When mutated by Phazon, Metroids gain various odd qualities (See Phazon for notes on Phazon-mutated Metroids). Exposure to beta radiation causes them to asexually reproduce by dividing, much like a cell undergoing mitosis.

The Metroids live on a mysterious energy that they drain from their victims. What this energy is is unknown, as 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 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.

Besides draining life energy from victims, Metroids have the ability to transfer stored life energy into another life form, healing it, as shown in Super Metroid. This stored energy can also be drained from the Metroid, allowing it to be used as a living rechargeable power cell.

It is also revealed through Pirate Homeworld Scans in Corruption that Metroids have a sensitivity to certain frequencies, a weakness that the Pirates exploited by subduing several Phazon Metroids in the Metroid Processing chamber.

Metroids were created by the Chozo on planet SR388 in order to keep the X Parasites at bay.

Metroid
"This protoplasm in suspended animation was discovered on the planet SR388. It clings onto Samus' body and sucks his 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." In Metroid, Metroids were said to have been originally discovered by the Galactic Federation while researching SR388. Not long after that, the Space Pirates boarded a ship in which some Metroids were being transported and stole the specimens, taking them to their base deep within the planet Zebes. Shortly after that incident, Bounty Hunter Samus Aran was sent to Zebes to destroy the Space Pirates and their stolen Metroids.

Metroid Prime
In Metroid Prime, a few surviving Space Pirates found the mutagen Phazon on the planet Tallon IV and used it to rebuild their army. They exposed the Metroids to it, along with many other life-forms, including themselves. This revealed two new stages in Metroid development: 'Hunter' Metroids which had orange pigmentation and two energy-extracting tentacles and 'Fission' Metroids, which split into two Metroids when attacked. These stages contradict the natural life cycle seen in Metroid II, and are called Tallon Metroids in Metroid Prime 2: Echoes. Also seen in the game is a creature called Metroid Prime, which is suggested to be a Phazon mutated creature with an unknown relation to Metroids.

In Metroid Prime 3: Corruption, various scan data on the Pirate Homeworld explains the contradiction in Metroid physiology as the result of being exposed to different atmospheres and other stimuli like Phazon. This may also serve to explain why the Tallon Metroids in the first two Prime games were not as resilient to damage as those seen in other games.

Metroid Prime: Hunters
Metroid Prime Hunters is the only game in the Metroid series that does not feature Metroids despite having Metroids in the demo version, Metroid Prime Hunters: First Hunt. It does, however, feature a new species: Quadtroid, a genetically engineered species that is similar in appearance and function to Metroids.

Metroid Prime 2: Echoes
In Metroid Prime 2: Echoes, the Space Pirates bring Metroids with them to Aether. Metroids in this game appeared with red membranes. The Ing later possessed some Metroids, creating Dark Metroids. Also seen are Metroid cocoons, which release very small infant Metroids which need to come in contact with Phazon in order to grow to the size of normal Metroids. Very young infant Metroids cannot yet absorb energy, and instead use ramming attacks to damage their foes. The logbook scan for these Infant Metroids suggests that the Space Pirates may have somehow created this Metroid strain to be less dangerous and easier to transport, supported by the fact that in the end of Metroid II: Return of Samus, the Metroid hatchling already is in its most common (larva) form when it hatches, as Samus approaches it--though this larva is much smaller than the standard ones.

Metroid Prime 3: Corruption
In Metroid Prime 3: Corruption, four new Metroids are introduced. These Metroids are the Miniroid, the Phazon Metroid, the Hopping Metroid and the Metroid Hatcher. Phazon Metroids are the replacements for the Tallon Metroids from the two previous games. These Metroids are Tallon Metroids that were raised on the Pirate Homeworld, and their eggs infused with Phazon. The different evolutions and stages of Metroids found in different Planets are explained by scans in the room Metroid Processing on the Pirate Homeworld.

Interesting to note, in a room on the Pirate Homeworld in Metroid Prime 3: Corruption, there are three empty tanks. When scanned, the first reveals that the Metroid sample taken from Zebes has proven highly aggressive, even for a Metroid. The second tank reveals that a particular strain of Metroid from Tallon IV has been moved for further examination. The final tank reveals that the SR388 Metroid has incredible DNA altering abilities and is being taken to a Research Station to be studied, referencing its evolutionary forms in Metroid II: Return of Samus and foreshadowing Samus's transformation in Metroid Fusion by the vaccine made of Metroid cells. This particular strain could explain the origins of the Hopping Metroid as the Hopping Metroid's appearance is rather similar to a Metroid in its Gamma stage, except for the infusion of Phazon. Since the player never visits the particular research station where the strain is taken and no Metroids can be left alive, the Hopping Metroid must have been created from the SR388 strain.

Metroid II: Return of Samus
In Metroid II: Return of Samus, seeing the dangers the Metroids posed to the galaxy, the Galactic Federation attempted to destroy them. After two failed attempts by the Federation's army to eradicate the Metroids on their home planet of SR388, they called on Samus Aran to deal with them, as she had previously been the only person able to survive several encounters with the creatures. It was in this game that the natural Metroid life-cycle was revealed.

The game begins with a total global Metroid population of 47, though the number displayed is 39 because 8 more standard Metroids are discovered before engaging the queen. Samus' goal was to explore SR388 and hunt the Metroids down one by one. As she progresses further into the planet, the Metroids continue to evolve further into their life-cycle, eventually culminating into the Omega Metroids. Samus eventually makes her way into the Metroid nest at the center of the planet, destroying several Metroids before engaging in a final battle with the Queen Metroid.

After the Queen was destroyed, an infant Metroid hatched and imprinted Samus as its mother (thus questioning the true instinctual intelligence of the average Metroid). Because of Samus's efforts, this infant was the last surviving Metroid in the galaxy. It helped Samus escape from SR388, and she took it back to the Federation Academy.

Super Metroid

 * "The last Metroid is in captivity. The galaxy is at peace..."

"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."

In Super Metroid, the Metroid larva that had imprinted on Samus was studied by scientists on Ceres Station; it was found that the Metroids' potential as beneficial creatures was as great as their destructive powers. Right after Samus left Ceres Station, the Space Pirates besieged it, killing everyone onboard. Ridley stole the Metroid larva, taking it back to the Space Pirates' rebuilt base on Zebes.

The Space Pirates quickly used beta rays to create a new army of feral Metroids from the Metroid larva. In Maridia, Samus also found Mochtroids, early Space Pirate attempts at cloning Metroids. While they could leech life-energy, they were very weak and could not latch onto their prey. At the end of the game, the Metroid larva sacrificed itself to save Samus from Mother Brain. Before dying, the Metroid demonstrated the life-saving properties that could have benefited galactic civilization (what the scientists revealed at the beginning the game): transferring energy to living beings instead of simply absorbing it. Its demise meant the apparent extinction of the entire Metroid species; it also demonstrated the Metroids' ability to show compassion. One noteworthy fact: the Larval Metroid grew to a tremendous size without moving on to the next stage of a Metroid's natural life-cycle (by the end of the game, it is actually bigger than the Queen Metroid was). It could be that prolonged exposure to beta-rays caused this unnatural growth; another possibility is that the Metroid had been removed from its natural environment (thus missing some sort of compound/chemical only present on SR-388) and was therefore restricted to the larval stage. A similar anomaly in size is found in the Omega Metroid from Metroid Fusion, where it has grown 3 times taller than Samus in comparison to the Omega Metroids from SR388 that are about as tall as Samus.

Metroid Fusion
Metroid Fusion takes place shortly after Super Metroid and is considered "Metroid IV" on the timeline. On planet SR388, the Metroids had been the top predators, and with them gone the ecosystem was thrown completely out of balance. Samus was hired to protect some Federation scientists who were studying the recovery of the SR388 ecosystem. While they were on the planet, Samus was infected with an X Parasite. She was rushed back to Federation Headquarters with a minimal chance of survival. It had recently been discovered that the Chozo had created the Metroids to prey upon the X Parasites, which were dominating the ecosystem of SR388. Using this information, the Federation saved Samus by injecting her with a Metroid vaccine made from a DNA sample of the deceased hatchling.

Later in Metroid Fusion, it was revealed that the Federation had a secret Metroid breeding program going on (see Restricted Lab), presumably based on clones of the last Metroid. The program was destroyed by a powerful X Parasite mimic of Samus, the SA-X. The entire section was detached from the station and ejected into space, just after Samus escaped, completely destroying the Federation's research. However, one Metroid had escaped and advanced to Omega level, and Samus had to defeat it before evacuating. Worthy of noting is the difference in size between this Metroid and the Omegas found in SR388, the latter which were only slightly taller than Samus; it is a possibility that the Federation had exposed the Metroid to an unknown radiation that caused its irregular growth, much like the theory for the Infant Metroid in the prequel. At this point, the only known Metroid DNA resides within Samus Aran.

Logbook entries
Metroid Prime: "Metroids are energy-based parasitic predators. The dominant species of planet SR388, Metroids can suck the life force out of living things. A Metroid latches 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."

Metroid manual
"This protoplasm in suspended animation was discovered on the planet SR388. It clings  onto Samus' body and sucks his 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 Guide
"This is a mysterious life form which was discovered on the planet SR388. It sticks to Samus’ body and sucks out his energy."

Metroid II manual
"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 manual
FLOATING LIFE FORMS - METROIDS

"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."

Metroid Zero Mission manual
"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."

Metroid Prime Pinball manual
"An energy based, highly dangerous parasite."

Official Metroid Fusion Website
"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."

Official Metroid Prime Website
"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.

''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."''

Official Metroid Zero Mission Website
"SPECIMEN ID# M-1A

"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)

Appearances in other media

 * Metroids, or a very similar creature, appeared in another Nintendo game, Kid Icarus (and the sequel, Kid Icarus: Of Myths and Monsters), under the name of Komayto, stated in the instruction manual to have come from another planet. This creature can be found flying around Skyworld in packs. Kid Icarus was created on the Metroid game engine.


 * 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 1up.


 * Metroids wander onto stages randomly in Metroid Prime Pinball and also have their own minigame, Metroid Mania.


 * A Metroid is a furniture item in Animal Crossing: Wild World for the Nintendo DS. It resembles the Baby in a large capsule. The piece plays the Super Metroid title theme song when tapped. This item is also in Animal Crossing: City Folk, but cannot be transferred from Wild World with the in-game catalog due to the item's rarity. In both games, it is one of many very rare treasures gained by shooting down Gulliver.


 * 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 Metroid 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.

Super Smash Bros Series

 * Metroids appear in a minor reference in Super Smash Bros.. In Super Smash Bros. Melee as a trophy as well as the Infant Metroid being seen in the opening cutscene, and make another appearance in Super Smash Bros. Brawl as an Assist Trophy, with the ability to latch onto opponents and drain them of energy. In Melee, the intro scene from Super Metroid is reflected off of the trophy, with the infant missing from the scene.

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

Super Smash Bros. Melee
''"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. Brawl
''"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)

Stickers

 * Metroid Metroid Prime Pinball - [Freezing] Attack +18 (All)
 * Metroid Metroid: Zero Mission - [Electric] Attack +20 (Samus, Zero Suit Samus)

Real-World Etymology
The word "Metroid" can be broken into two parts: "Metro" (meaning "of the womb", referring to metrology, or a tunnel system) and "oid" (indicating a "similarity, not necessarily exact, to something else" or "having the likeness of"). The word also resembles "meteoroid", which refers to space debris. Its root word meteor comes from the Greek "meteōros", meaning "high in the air".

Trivia

 * The eggs which can be found on the Pirate Homeworld in the room Metroid Processing are in a tank with large metal 'hands' are clasping them. This is similar to the scene in Jurassic Park, where dinosaur eggs are being produced and hatched with a similar metal claw.
 * Scanning the shields holding back the Metroids in Metroid Processing reveals that Metroids can be calmed by using hypersonic frequencies of a certain pitch, which keeps them calm and prevents them attacking. It is unknown how the creatures detect the sound.
 * The first Metroid that Samus encounters in Metroid Prime, titled BR5497 is in a containment tube very similar to the hatchling's in Super Metroid.
 * 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 to attack the victim, or (as seen in a cutscene in Zero Mission) a group will feed on a victim together.
 * Strangely, although Infant Tallon Metroids are said to be used as batteries, a scan in the Metroid Processing room on the Pirate Homeworld in Metroid Prime 3: Corruption (next to the controversial Metroid Dread scan) says that a project to use Metroids to power guns and other mobile weapons failed. It could be possible that this project was for the use of adult Metroids, instead of the weaker and more manageable Infants.
 * The full limitations of Metroid behavior has not fully been explored. However, it could be possible it extends beyond the simple feeding instinct- for example, the infant Metroid 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 back into her.
 * In Metroid Fusion, Samus is saved from X infection by a Metroid vaccine only made from Metroid cells. This suggests that the Chozo engineered even the Metroid's base cells to prey upon those of the X.
 * 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.