Knuckles the Echidna (ナックルズ・ザ・エキドゥナ, Nakkurusu za Ekiduna?), or "Knux" for short, is a red 16-year-old anthropomorphic echidna, who is both physically powerful and highly resilient. He has a white crescent birthmark on his chest. The character is both a friend and a rival to Sonic the Hedgehog. Knuckles' name is derived from the four knuckles, two on each hand, which are actually sharp spikes. According to official Sonic Team polls, Knuckles is the fourth most popular character in the series. His first game appearance was in Sonic the Hedgehog 3, released on February 2, 1994 for the Sega Mega Drive/Genesis. He was described as being 15 years old when he made his debut, but since Sonic Adventure, he is now given the age of 16. Knuckles has two spikes or claws on each hand, and his dominant trait is his strength. He can also glide by trapping air under his dreadlocks, and is very skilled at a wide variety of martial art forms.