Cacti on some Galápagos Islands grow like small trees to stay out of reach of hungry tortoises.
The raised opening of the saddle-backed tortoises' shell likely evolved to counter this cactus defense.
The raised opening also helps saddle-backed tortoises compete while stretching their necks during dominance interactions.
Image credit: © Frank J. Sulloway. All rights reserved. Used with permission from the artist; image found here.