Arboreal, or tree-dwelling, tarantulas are characterized by a longer, flatter body and the ability to rapidly move and leap from one spot to another in the canopy. Since they don't have the safe retreat of an underground burrow, they need to be able to safely and quickly move throughout their habitat.
They also tend to be more sociable with their own kind than their ground-living brethren. Heavy seasonal rains means fewer safe and dry hiding spaces, and the need to tolerate close quarters. Yet another amazing adaptation showcased by these remarkable animals.