I'm pretty sure crocs are especially nocturnal.

Wiley InterScience :: Session Cookies

Ultrastructure of duvernoy's gland from the wandering garter snake, Thamnophis elegans vagrans (Serpentes, Colubridae)
Kenneth V. Kardong, Daniel L. LuchtelDepartment of Zoology, Washington State University, Pullman, Washington 98164, and Department of Environmental Health, SC-34, University of Washington, Seattle, Washington 98195

Abstract

In addition to the supralabial glands (strips of glandular tissue lying along the maxilla), most snakes of the family Colubridae possess an enlarged oral gland lying behind the eye and emptying near the rear maxillary teeth, the Duvernoy's gland. Duvernoy's gland is most probably homologous to the venom gland of viperid and elapid snakes, and occasionally has been implicated in cases of human envenomation.
I just grabbed the first article I could find, there are better ones. Look for ones by a 'Dr. Bryan Fry'. He has written a lot on venoms of "nonvenomous" snakes. And venoms in general.