Hungry Lumas are pink, slightly chubby Lumas that have visible mouths (unlike regular Lumas) and appear in both Super Mario Galaxy and Super Mario Galaxy 2. Similar to Lumalee and Comet Tico, Hungry Lumas are always seen carrying two sticks (one in each hand) which will either have color-changing Star Bits or Coins on the end, the latter appearing only in Super Mario Galaxy 2.
Hungry Lumas tend to appear as part of hidden star missions; in Super Mario Galaxy, they will also appear on the Comet Observatory. In Super Mario Galaxy 2, Hungry Lumas appear on the World Map, and can be called to Starship Mario. When Mario finds a Hungry Luma, he must feed it a certain number of Star Bits or Coins, making it larger and larger, until it transforms into a new planet or galaxy; the transformation is usually permanent, and the resulting planet or galaxy can be visited at the player's leisure. The only Hungry Luma that reverts to its previous form after is the one that transforms into the Tower Planet in the Good Egg Galaxy; this is done as a part of one of the galaxy's main missions, and thus the Luma must be fed 100 Star Bits to transform each time the level is replayed, since the planet will not remain after the level has been completed. Often, the player will be able to travel to the newly-created planet or galaxy via a pink Launch Star right after the Hungry Luma transforms; an exception is the one that transforms into the Van-Van Vanish Lv2 Zone in the Sea Slide Galaxy, as the planet is accessible by cannon.
Hungry Lumas found throughout individual galaxies will usually require a smaller amount of Star Bits to transform into planets, while Hungry Lumas that appear on the Comet Observatory or are called to Starship Mario will require larger amounts of Star Bits to create entire galaxies. In Super Mario Galaxy, there are a total of seven Hungry Lumas that will appear on the Comet Observatory (one outside each dome and the Gate. In Super Mario Galaxy 2, seven more Hungry Lumas can be called to Starship Mario from each of the seven worlds. Both games also feature seven planet-creating Hungry Lumas, for a total of 28 Hungry Lumas.