Reticulated humming frog
Scientists do not know whether the reticulated humming frog and the tarantula both help each other or whether the tarantula helps the frog but not the other way around.  The frog lives in the tarantula burrow, where it is safe from drying out during the day.  Other animals that would eat the frog stay away from the tarantulas.  However, scientists think the reticulated humming frog might help the tarantula too.  They have seen parasite fly larvae on young tarantulas.  They think the frog might help the tarantulas by eating flies that try to get into the burrow.