Nature's Pictures of the Year

Nature has posted its "most striking" pictures of the year. Above, tornado-spawning thunderstorm in Nebraska, by Camille Seaman.

Giant ringworm (Nereis pelagica), 25 cm long (10 inches) and as thick as a finger, photographed in the White Sea by Alexander Semenov. (More of Semenov's wonderful work here.)

Bat embryos, by Dorit Hockman.