Draygon

The Draygon is a major boss from Super Metroid. It is a sort of waterborn crustacean, with a hard outer shell and soft underbelly. It seems to be a fully developed Evir, and even has a few hatchlings{fact}, which are present in the chamber that it dwells in. It is found in one of the last accessible rooms of Maridia. Its defeat allows access to the room which holds the Space Jump ability, and is one of the four bosses necessary to defeat in order to enter Tourian as it is depicted on the Golden Statues. This has led to the possibility that the Draygon and Phantoon are high-ranking Space Pirates in the same way Kraid and Ridley are. It may indicate that the Draygon and Phantoon are not mindless creatures, but intelligent beings, despite their monstrous appearances and seemingly animalistic behavior.

Super Metroid manual
"The Draygon has an armor-like hard shell which gives it a lot of defensive strength."

Battle
Once Samus enters the chamber, three Wall Cannons will begin shooting electrical spheres in her direction, and will continue to do so for the entire upcoming battle, providing support for the boss unless she destroys them. Also present in the room is a small group of dark green Evirs which will be swimming around near the seafloor, and will swim out of sight after a few moments. Their highly protective "parent" will swim in with great haste mere seconds later. The Draygon will quickly jet back and forth in the chamber, disappearing past the walls, swimming in swift arcs in an attempt to tackle Samus. Its body is nearly completely covered in a tough impenetrable shell, save for its soft underbelly, which is susceptible to Super Missiles.

Occasionally, between the swift swimming arcs, the Draygon will slow down and release several dozen globs of gray mucus from its mouth as it reappears, resembling Boyons. These can attach themselves to Samus, slowing her movement and allowing Draygon to grab onto her and deal massive damage with its claws and tail.

Throughout the battle, the Draygon's stomach will gradually change from a pale yellow to a very bright crimson, depending on how much damage Samus has inflicted. Once defeated, its stomach bursts, and the creature will fall while its eyes convulse in every direction, releasing its final cries and floating down to the seafloor. As its eyes close, its children will slowly reappear and burrow into the ground with the body in complete silence.

Samus can defeat the Draygon easily by destroying the Wall Cannons on the walls. By allowing the Draygon to grab her, she can then fire the Grappling Beam at the sparking wreckage of the cannons. The Power Suit will act as an electricity conductor, transferring an intense electrical charge into the Draygon's body. After a few moments of intense shocking, Draygon's health will rapidly deplete to nothing, and end the battle rather quickly. Note that the electrocution of Draygon will also cause a noticable amount of damage to Samus as well. However, ROM hacks have proven that it is not the electricity itself that kills Draygon, but rather the act of grappling to an object. If Samus grapples a regular Grapple Block added to the chamber, Draygon can still be killed using the glitch, although it will not cause any damage to Samus. (See here for the trick, around 1:46.)

The battle with Draygon also provides the game's only opportunity to exploit the blue suit glitch. Though difficult, this glitch allows Samus to permanently retain the properties of speed boosting, even when walking at a normal speed. The glitch is activated by repeatedly using Draygon's mucus attack to charge a shinespark, and hitting Draygon with a hyper jump. When Draygon dies this way, the blue suit is activated, until certain actions (dashing, shinesparking) cancel it.

Trivia

 * Human skull-like shapes can be seen on the Draygon's head. These shapes greatly resemble a Covern's overall appearance.
 * Deceased bioforms can be seen in the Draygon's room; most of these are Scisers. They may have been used as sustenance for the Evirs located there and/or Draygon.
 * The Super Metroid Player's Guide refers to the Draygon as both a mutant and reptile.
 * The secret electrocution killing method is mirrored in another boss fight in Metroid Prime 2: Echoes, for the Grapple Guardian.
 * The Draygon's roar is very similar to that of the daikaiju Anguirus.
 * Although the Draygon's gender has never been specified, it is referred by many fans as a female due to the Evirs, which appear to be its offspring.
 * Several cube-like structures can be seen floating in the water. Their purpose is unknown.
 * As of Metroid: Other M, Draygon is the only one of the 5 Space Pirate commanders (Mother Brain included) to be fought in only one game.