An introductory page how animals develop certain traits in order to meet their survival needs.  It specifically describes convergent evolution: when animals who aren’t even related to each other develop the same or similar traits, due to similar environmental needs. Each two-page spread is dedicated to a particular trait, and how two different animals use that trait for survival.  A final paragraph on each page contrasts the two animals, explaining how they can share similar traits even if they’re not actually closely related.  All of this is illustrated with large color photos that support the text well.