Did you know that "male lions defend the pride's territory while females do most of the hunting"? Did you know that "the name humpback whale describes the motion it makes as it arches its back out of the water in preparation for a dive"? What about this one: "ostriches have the largest eyes of any land living animal and they measure 50 mm (2 inches) in diameter"?
Google now shows random facts about animals in the "did you know" section of the Knowledge Graph card. They're extracted from various sites and Google actually links to the source.
Some example of queries that return random facts: [cat], [lion], [tiger], [alpaca], [giraffe], [ostrich], [duck], [elk], [raccoon], [shark]. It's worth pointing out that you can get another random fact by reloading the page or searching again for the same animal.