Nurse Shark - Contains a picture, and describes how dangerous this shark is compared to others. - http://www.five.tv/programmes/killersharklive/sharks/nurse/
Ginglymostoma Cirratum - Contains a physical description, plus information on range, habitat, and feeding behavior. - http://marinebio.org/species.asp?id=91
Wikipedia: Nurse Shark - Encyclopedia article gives a brief overview of this animal. - http://en.wikipedia.org/wiki/Nurse_shark
Grey Nurse Shark - Information on how large this species gets, and its sharp pointed teeth. - http://www.amonline.net.au/fishes/students/focus/grey.htm
Florida Museum of Natural History: Nurse Shark - Includes a picture, common names for the shark, and where it's found in the ocean. - http://www.flmnh.ufl.edu/fish/Gallery/Descript/nurseshark/nurseshark.htm