Ever wondered why sharks are coloured dark above and light below? No, it's not a faulty tan! Countershading prevents sharks from being detected easily by ensuring that a minimal silhouette is cast. The dark blue-grey coloration on the dorsal surface blends with the water below and makes it difficult to view from above, while the white on the ventral surface blends with the sunlight, making it difficult to view from below. Full marks to evolution for predator-design!
The cartoon first appeared on my Gocomics page this month. You can subscribe to Green Humour on Gocomics by visiting http://www.gocomics.com/green-humour and clicking on that nice-looking green plus button below the comic.