Brazilian wandering spiders

The name cottonmouth derives from the way they live.

An excerpt from the article 14 facts about Brazilian wandering spiders

They are spiders that do not weave webs but roam the land in search of prey. They are active at night and rest during the day in burrows, cavities, under rocks or in fruit leaves.

Some species live exclusively in forests, while others, such as Phoneutria nigriventer also find their way well near human habitation.