A person caught between a rock and a hard place is in an unenviable position. For a Chuckwalla, though, such a spot can be highly desirable.
The Chuckwalla, a large potbellied lizard common in the Southwest, favors rocky hillsides and boulder-strewn flats. One reason it prefers these landscapes is that they offer lots of hiding places -- crevices into which the Chuckwalla can retreat when disturbed or frightened. And if a foe tries to extract a Chuckwalla from its hiding place, the lizard inhales deeply and inflates its lungs to three times their normal size. Thus expanded, it becomes tightly wedged in the crevice and almost impossible to remove.
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