Sonic the Hedgehog platforming of the main levels. The 16-bit "Sonic the Hedgehog " consisted of a giant rotating maze, which many considered a major technical achievement. The most common special stages, however, were segments with the character running through a long tunnel to collect certain items. 3D "collect item" levels, as in "Sonic 3" and "Sonic & Knuckles", used the same perspective but had Sonic collecting all the blue-colored orbs on the surface of a giant sphere. Finally, "Sonic Advance 2" employed a 3D ring-collecting stage, and "Sonic Chaos" ("Sonic and Tails" in Japan) used a variety of gimmicks for its levels.
Sonic hedgehog B. Lewis, identified genes that control the segmentation pattern of the "Drosophila" embryos. The "hh" loss of function mutant phenotype causes the embryos to be covered with denticles, small pointy projections resembling the spines of a hedgehog. Investigations aimed at finding a "hedgehog" equivalent in vertebrates by Philip Ingham, Andrew P. McMahon, and Clifford Tabin, revealed three homologous genes. Two of these, "desert hedgehog" and "Indian hedgehog", were named for species of hedgehogs, while "sonic hedgehog" was named after Sonic the Hedgehog, the protagonist of the eponymous video game franchise. The name was devised by Robert Riddle, who was a