In this video, we learn about the symbiotic relationship between frogs and tarantulas. Although it may look as if the tarantula in this video is "keeping the frog as a pet", it's actually a bit more complicated. Both the frog and the tarantula are using each other for safety and protection here.
Watching a little frog crawl into the underground habitat of a tarantula doesn't seem like it would end well for the frog. This isn't always the case, though. Certain species of frogs and tarantulas actually coexist in a mutually beneficial way.
This often takes place in tropical environments. The tarantula protects the frog in its burrow, while the frog helps the tarantula by consuming small insects and pests that would otherwise harm the tarantula and its eggs. This arrangement benefits both creatures since the frog gets a safe nook to hide in, and the tarantula gets to live in a pest free home.
See also: The sounds of tree frogs and howler monkeys in Costa Rica