The quote "Nature is cruel, but WE don't HAVE to be" is from Temple Grandin. At least, I think it's from Temple Grandin, the influential autistic female animal behaviorist. It's a line from the Claire Danes movie of the same name.
The shapes and proportions're based on grey reef sharks.
The version above is an improvement on the version pictured below, because the one below is so loosely fitting. A good tessellation should fit together "without gaps and without overlaps". The tightly fitting one (above) I did in July of 2013 based on suggestions from fellow tessellation artist Bruce Bilney. The "Sharks Cove" it's anamed after is a popular but usually sharkless shore dive for SCUBA affecionados on O'ahu, in Hawaii.
The original version, below, I made for a Spoonflower.com fabric pattern design contest in August 2011.
Update: Well, this is humbling: I scored rather poorly in the contest. I'm only slightly above the middle of the pack, and got less than a third of the votes the winner received. There's definitely room for improvement.
The large gap between the sharks pushes this older version art outside the strict definition of "tessellation art". Good tessellation art has tiles that "fit together without gap or overlap". The older version has immense gaps. Don't use it as an ideal example of how to tessellate. Use the newer version instead.