Normal: "An enigmatic fiend that runs across the desert. Whether it bears good fortune or bad, none can say. No one has survived its 1000 Needles attack long enough to find out." Oversoul: "A fiend that looks innocent enough, but when it gets mad, it really gets mad. Nothing makes it madder than low HP. Then it's time for mad attacks." — Scan
The leader of the cacti and Cactuars is an ancient cactus named Marnela (meaning "Grandmother" in the Cactuar language), who has a special bond with a young Al Bhed boy named Benzo. Benzo is the only person who is able to understand their language. The Cactuars in this area appear as realistic cacti. It is explained that the cactus stage is how Cactuars appear when they are born, then later in their lives, they uproot themselves and become what players know as a Cactuar. When they reach a certain level of maturity, they root themselves again, becoming cacti once more. It was believed a millennium ago that some Cactuar left Bikanel and migrated to the Thunder Plains, becoming the Qactuar.
The Cactuar is fought in Bikanel in Chapter 5. Two also fight alongside the Jumbo Cactuar.
Cactuars appear first in the Grand Cup: Hard. A duo of them is always the last team the player must face when they complete the cup for the fourth time. Defeating them unlocks the Cactuar Cup in which every team includes at least one Cactuar. The player must have a Cactuar in their active battling party to enter it. Cactuars can be recruited by setting up an S-pod in Bikanel after unlocking the Cactuar Hollow.
Cactuars in the Fiend Arena are much more dangerous than their counterparts in Bikanel and Via Infinito. They can use strong abilities like Fireworks or Meteor and they repeatedly put themselves in Haste. At low HP they will occasionally use 10000 Needles and subsequently heal themselves with White Highwind.