Utsutsubo

Eels are aquatic creatures encountered in the Wario Land series, or more precisely in Wario Land II. Appearing like snake-like fish, they resemble their real world-counterparts. Additionally, Eels sport white patterns on their backs, and their mouths end in a pair of powerful jaws with tooth-like extensions, which allow them to get a solid grip on their prey. Eels apparently prefer to live in submerged caves with strong currents. They are all orange in the Game Boy Color-enhanced version.

''Wario Land II
Eels are a very rare enemy in Wario Land II. They make their only appearance in a cavern of the level Get in the Tea Cup. Wario has to traverse their habitat in order to reach the SS Tea Cup, the ship of the Black Sugar Gang who stole the majority of his possessions. The eels reside in their holes and wait for Wario to get in reach. Once they sense a good opportunity, they rise and attempt to latch onto the greedy treasure hunter. If they succeed, they drag Wario down their cave and pull him into the strong currents at the ground, which forces the player to restart the cave segment. The player will also lose a few coins, so the Eels' attacks should be avoided. However, in one particular situation, succumbing to an Eel's bite is the only way to reach the hidden treasure of the level. Because of Wario's lack of underwater attacks, Eels cannot be harmed in any way in this game.