Fire Snake

Firesnakes are long, snake-like Lava Bubbles with bodies made up of fireballs. They have appeared as uncommon enemies in several Mario games, mostly in Desert-themed levels.

Super Mario Bros. 3
The first appearance of Firesnakes is in Super Mario Bros. 3, where they appear in Desert Land. If a Firesnake sees Mario, it begins to chase him by bouncing and trying to collide with him. A Firesnake can only be defeated by either hitting it with a Shell or Hammer, by having Mario touch it while he is empowered by a Starman or by having Mario whack it with his tail as either Raccoon Mario or Tanooki Mario or a stomp from Statue Mario. He can also make them to fall into an abyss, however, they reappear after a few seconds. In the original NES version, Firesnakes do not have eyes, whereas they have them in Super Mario All-Stars and Super Mario Advance 4: Super Mario Bros. 3.

Super Mario World
While Firesnakes did not appear in Super Mario World, a subspecies called Bound Fire did.

New Super Mario Bros.
Firesnakes also appear as uncommon enemies in New Super Mario Bros. in the stage 2-5. These Firesnakes will try to attack Mario by chasing him by bouncing and by trying to touch him, like in Super Mario Bros. 3. The Firesnakes of New Super Mario Bros. can be defeated by throwing a Shell at them and by touching them when Mario is empowered by a Starman or Mega Mushroom. He can also make them to fall into an abyss, however, they reappear after a few seconds. They only appear twice. They are depicted with eyes similar to re-releases of Super Mario Bros. 3.

New Super Mario Bros. Wii
They also appear in the game New Super Mario Bros. Wii acting like they did in New Super Mario Bros., but they have a new ability. After one or two hops, their heads will enlarge, then go back to normal size. They only appear in World 2-3 and can be defeated with a Starman or ice balls.

New Super Mario Bros. 2
Firesnakes reappear in New Super Mario Bros. 2. This time they also appear in lava-themed levels, and behave the same as they do in New Super Mario Bros. They appear in World 2-4 and.

New Super Mario Bros. U
Firesnakes reapper in the Wii U title New Super Mario Bros. U acting exactly as in the predecessors. They have their own level called Fire Snake Cavern (with a space) located in Layer-Cake Desert in which they are very common alongside the Fire Bros, and can now be eaten by any Baby Yoshi.

The Adventures of Super Mario Bros. 3
Firesnakes make a few minor appearances in The Adventures of Super Mario Bros. 3.

Princess Toadstool for President
In "Princess Toadstool for President", Mario and Luigi end up in Dark Land and while there, they get ambushed by many enemies, including a Firesnake.

Crimes R Us
In "Crimes R Us", the Koopalings break in to the Mushroom Kingdom Treasury, using a Chain Chomp to open the barred window, a Ptooie to blast a hole in the wall, and a Firesnake to bust a hole in the roof.

Recycled Koopa
In "Recycled Koopa", a Koopa Zombie attacks Luigi with three Firesnakes which get out of his case.

Nintendo Adventure Books
In Double Trouble, a swarm of Firesnakes can be encountered in the Koopahari Desert if Mario decides to take a shortcut to Fort Koopa. Depending on how an accompanying puzzle is solved, Mario either dodges and escapes them, or is sent running after being singed twice, losing his Super Mushroom in the process. Far fewer Firesnakes can be encountered on the main road to Fort Koopa, and Mario can easily avoid them.

Two Firesnakes appear as competitors in the International Mushroom Games in Leaping Lizards, being members of a team called the Sneaks. During the Beetlebowl, an all-team game, they may (depending on who the reader chooses as their offensive line) leap into the middle of the ring when the event begins and flare up, blinding everyone nearby besides Roy Koopa and their Rocky Wrench teammate, due to their sunglasses. When one of the Firesnakes grabs a Hoopster and tries to dunk it into the Mushroom Kingdom Royals's bucket, Mario unintentionally stops it when the Mushroom King (who had been turned into a rabbit) hops by, causing him to sneeze and blow the Firesnake out. What other events the Firesnakes compete in besides the Beetlebowl are unspecified.

In Koopa Capers, Wendy O. Koopa, needing some Firesnake scales for a potion she is brewing, captures several and locks them in a freezing cave in the Magma Pits, causing them enter a catatonic state and begin shedding.

Yoshi's Safari
In Yoshi's Safari, only two Firesnakes appear as mini-bosses; in order to defeat these Firesnakes, who will try to touch Mario and Yoshi, Mario must blast them repeatedly with his Super Scope.

Mario Kart DS
In the Mario Kart DS course Desert Hills, an Angry Sun shoots Firesnakes (they do not have eyes in this game) down on the course where they cause any racers that touched them to spin out.

Mario Kart Wii
Firesnakes also appear in Mario Kart Wii, acting the same way as they did in Mario Kart DS. They appear on two courses; one of which is Desert Hills from Mario Kart DS itself. They also appear in Grumble Volcano where they are found near the end hopping out of pipes on the side of the course, attempting to spin out any racers that touched one. They have a new appearance in this game; they have eyes on their heads.

Mario Kart 8
Firesnakes reappear in Mario Kart 8 as obstacles for the racers on Grumble Volcano, which returns from Mario Kart Wii.

Trivia

 * The Firesnakes of Yoshi's Safari are blue, possibly symbolizing their status as mini-bosses, as a blue flame is hotter than a red one. Additionally, the Firesnakes of Yoshi's Safari have eyes on all their body segments, instead of just one.
 * Firesnakes were originally written into the desert sequence of the Super Mario Bros. film, but were cut for unknown reasons. Scripts state that they "[...]resemble moray eels, their mouths filled with pointed piranha-like teeth," and that "They gnaw through the skin, burrow into the body cavities, and lay their larvae. It can take weeks for the host to die."