Over time, human beings have blazed their way into the night with fire and artificial light, but we are not true creatures of the night. This Topic in Depth explores the world of nocturnal animals. From Island Discovery & Training, the first site allows visitors to listen to the sounds of several nocturnal animals. After guessing who made the sound, visitors can link to information pages for all but one of the mystery animals (1). Next is an information sheet (2) from BioMedia that answers the question: How Do Animals See In the Dark? The third site, from Enchanted Learning, provides coloring sheets and brief profiles for many nocturnal animals including the Amur Tiger, Badger, Crocodile, and Kinkajou-just to name a few (3). From the Fairbanks Museum & Planetarium in Vermont, the fourth website contains a six-page lesson plan (for students in grades one to eight) emphasizing different senses; and the roles and adaptations of nocturnal species (4). The fifth site, from Science News Online, contains an article addressing research on the ecological impact of artificial nighttime light on nocturnal animals (5). From Wild Asia, the next site contains an article by travel writer and environmental educator David Bowden, that describes his experience watching a marine turtle lay her eggs on Malaysia's Turtle Island (6). The seventh site, from PBS-Nova Online, briefly describes the work of zoologists who study nocturnal and burrowing animals of the Kalahari (7). From this site visitors can also link to a section that discusses how several different animals see at night. The final site, from the University of Utah-John Moran Eye Center, contains information about the role of photoreceptors in vision (8). This Photoreceptors section is part of a comprehensive electronic tutorial regarding neural organization of the mammalian retina.