Ultraviolet

The northern blue-tongued skink's tongue does more than look blue — it strongly reflects ultraviolet light, with the rear reflecting roughly twice as much as the front. Normally camouflaged, it gapes its mouth at predators to flash the UV-bright rear in a deimatic display.

A giraffe's tongue reaches 45–53 cm with a tip colored deep blue, black, or purple. The dark hue comes from melanin, and the leading explanation is ultraviolet protection: giraffes spend 16–20 hours browsing with the tongue out, so its most exposed part needs sunscreen.