Chykka

Chykka was a massive dragonfly-like creature that lived in Dark Torvus on Dark Aether.

The Chykka was born as a larva, which cocooned itself to turn into the Chykka Adult. If the Chykka Adult is exposed to the poisonous water of Dark Aether, it will transform into the Dark Chykka, who can hatch mutated Chyklings, miniature adults who have skipped the larval stage entirely. This creature is fought in Metroid Prime 2: Echoes as the Guardian of Dark Torvus Temple. Defeating it earns Samus the Dark Visor.

Battle
In Samus's battle with Chykka, she must first free the Chykka Cocoon from a wall, which then hatches into a rather dim-witted Chykka Larva. The Larva will swim around Samus' platform, disturbing Dark Shredders whom Samus can destroy (and are mainly there to distract Samus as Chykka dives, though they serve as a reliable supply for Energy and Ammo). Chykka will eventually dive down, then burst up, crash into the water, and send shockwaves at Samus, much like the Jump Guardian, but on a larger scale. This is the time to damage Chykka. If Chykka's shockwaves get Samus, she will be pushed into the poisonous water. The Larva will sometimes leap into Samus' platform, trying to eat her. Samus must dodge the tongue and damage the Larva with beam weapons, as only those will work. If Samus hits the Larva's mouth two or three times with charged shots, the Chykka will be momentarily stunned - and she can take this opportunity to lock on to the lower weak point and fire a Super Missile to inflict massive damage.

Once Chykka is hurt enough, it will collapse and the water will slowly drain lower. Chykka will then quickly metamorphose into the adult Chykka, who splits the platform into three pieces, each with a Light Crystal. At this point Chykka tends to strafe from side to side, making it a more difficult target to hit than its size would suggest, while shooting streams of poisoned water at Samus. Samus must stun Chykka with Beam weapons (Dark Beam being most effective), grapple behind it, and damage its four weak spots on its back with missiles. Seeker Missiles will also work. A Super Missile will destroy its weak point in one round.

Once all of Chykka's wings are damaged, it will fall into the water and fill its abdomen with the toxic water and becomes a Dark Chykka. It will blast Chyklings at Samus, and Samus must damage its abdomen; as a dark creature, charged Light Beam shots are most effective. After some time the water will drain away, and Samus must repeat the process. After dying fully, the Dark Visor appears, the door to Dark Torvus Temple will open, and Samus can transfer the energy back to Torvus Bog on Aether.

Humorously, after the Chykka is defeated, Samus can scan its corpse on the bottom of the upper part of the temple, which assures her that this time the creature is gone for good. The scan is as follows:

"Bioscan complete. Target Chykka has been terminated. Lifesigns are at flatline. No regenerative ability in effect. No evidence of symbiotic corpse possession. Resurrection does not appear likely."

Other

 * This is the music heard when battling the larval form of the Chykka:.
 * This is the music heard when battling the adult form of the Chykka:.

Trivia

 * Although the Chykky is clearly switching between light - and dark form, the light form seems to receive no damage of Dark Aether's atmosphere or water, similar to the Amorbis.
 * There is a glitch that, when Samus shoots the cocoon off while in the Dark Water, she will gain an "Omega Jump" that allows her to jump extremely high. However, the glitch is canceled when Samus leaves Dark Torvus Bog (travelling between Light or Dark worlds makes no difference) or if she steps in the water again. This glitch has been fixed in the Wii version.
 * The Chykka is the only guardian whose nature is not foreshadowed in any way by something in the Light version of its realm; it's also the only Guardian to leave behind a corpse.
 * The Adult Chykka's theme resembles the "minor boss" theme from Super Mario 64:.
 * The Chykka Larva resembles the Chestburster, an alien life form from the Alien film series. However, unlike the chestburster, the Chykka Larva has arm-like appendages, while the Chestburster is more like a worm or slug in most appearances. Additionally, the coccoon that the Larva encases itself in after its first battle is unmistakably Gigeresque in appearance.
 * The Chykka is called Anophelia in the Italian version of Echoes.
 * The Chykka Adult's wings slightly resemble those of the daikaiju Megaguirus from the Godzilla franchise. Additionally, Megaguirus has two forms, a larva form that resides in water and an Imago form which is a giant dragonfly.
 * The roars of the Larva form are recycled sound effects from the death of the Metroid Prime.
 * The Chykka can reproduce asexually when exposed to Dark Water.
 * The Chykka Larva is similar to the Korakk Beast. Both have double K's in their name, neither have visible eyes and both fire their tongues to pull Samus towards their mouths.
 * The Chykka Larva resembles a silverfish. Interestingly, silverfish are also called "fishmoths".
 * The battle with the Vorash in Metroid: Other M resembles the battle against the Chykka Larva.
 * The Chykka Larva emerges from a cocoon, this is the opposite metamorphosis as it happens with insects on earth, where the larva turns into a cocoon (although another cocoon appears after the Dark Water level lowers, which the Chykka's adult form quickly emerges from - the first "cocoon" may in fact have been an "egg").
 * The battle with the dragon Perkele in Avalon Code is similar to the fight with the Chykka Larva.
 * The Chykka is the only "non-final" boss in the entire Metroid Prime Trilogy that has separate health bars for each stage of the fight.
 * The Chykka Adult resembles a large War Wasp.

Chykka Swimmer
In the beta of the game, the Larva was called Chykka Swimmer and had this scan:

"Morphology: Chykka Swimmer Swimming Insectoid Guardian. Target has entered a state of frenzy. Evasive action recommended. The Chykka has been temporarily disabled by your attacks. Evasive action recommended. Target has become enraged and entered a state of frenzy. Collision-based attacks are likely."

Gallery
Чикка Chuca