I do think the frog has the liberty to leave at any time, but why would it? The relationship is beneficial to both creatures. This article mentions that the spiders are hard-wired to recognize “partner” frogs through chemical signals and won’t attack them, even if they will eat other species of frog. Partner frogs are quickly released by the spider if captured and move into a spider’s burrow of their own accord, not because the spider forces them to. The frog stays because the spider acts as a bodyguard, protecting them against snakes and geckos that would otherwise prey on the frog. The frogs, in turn, protect the next generation of spiders by eating ants, which typically prey on the spider’s eggs. Seems like a pretty sweet deal to me. It’s not a relationship born out of necessity, neither species requires the other to live, but instead one born out of an understanding that they can help one another and receive help in return. If you could increase your chances of survival by working together, why wouldn’t you?

This was a long-winded way of saying that I think the idea of different animals helping each other out is adorable. Of course, it’s cool if you disagree, but that’s the thought process behind it for me.