The setapin is an offshoot of the limapins, and have adapted to feed on two of the lower organisms in the food web (these being the two species of ghastchomps). Partially because they feed on such small organisms, they have shrank to roughly half the height of their ancestor; however, this shrinking in size has also been caused by a new, fantastic adaptation. This has allowed them to not replace their ancestor.
Setapin have grown very small and equally fine hair-like structures made from the skin that allow them to more easily hang onto the walls with their suction pad-like feet. The outside of these feet have also adapted a skin covering to provide a less awkward walk. This skin is double-folded and allows the suction pad foot to still shift its shape when moving, and therefore does not actually detract from their ability to move.
Little else has changed in the species. To feed on finear ghastchomps, they will attempt to sneak up on it from behind, generally while it attempts to eat its own prey, the flanged bubblehorn. This is due to the sensitivity of these ghastchomps' ears from the front.