Back in 2012, Lauren Esposito and a team of scientists trekked through the lush forests of the Dominican Republic in the Caribbean. Eventually, the group came to the mouth of a cave. After putting on thick gloves and hard hats with headlamps, they stepped into the darkness. The cave was overwhelmingly hot and humid, and filled with thousands of bats. It was also crawling with what the researchers had come in search of: spiders. The creatures were climbing all over the rock walls.