are yellow. Females are suggested to have lighter bands and markings on their bodies. This is not an effective way of judging the sex of H. gigas, as coloring differs slightly between all individuals. Hatchlings and juveniles are much darker in coloration and do not have the typical dark eyes of the adults. They more resemble a garter or water snake than their mature counterparts. In captivity, hypomelanstic animals have been produced. These animals vary in coloration, from some having only slightly lighter colored saddles, to those that are almost patternless. A melanistic population found in Tocantins, central Brazil, was originally describe as a new species of Hydrodynastes, H. melanogigas, but genetic evidence indicates that this population is composed of melanistic H. gigas. Geographic range In South America, H. gigas is found from eastern Bolivia to southern Brazil, and in Paraguay and Argentina. Habitat H. gigas generally lives in wet, humid areas, and marshlands, typically within the tropical rainforests that are common within its range. However, the false water cobra has also been observed in dryer areas, although this is not its preferred habitat. The preference of wetlands as a habitat for H. gigas contributes to its common name of false "water" cobra. Behavior H. gigas is primarily a diurnal species. It is also a very active and inquisitive snake, which spends much of the day climbing, burrowing, and even swimming. Temperaments can vary considerably between specimens; some are very docile and reluctant to bite, whilst others are very defensive and even aggressive or intimidating. Captive-bred specimens can become quite tame and trusting, and many exhibit a high level of intelligence. Feeding In the wild, H. gigas primarily feeds on fish and amphibians, but will take small mammals, rodents, birds, and even other reptiles. In captivity, they can be introduced to other types of food, as well. Venom The posterior maxillary teeth of H. gigas are enlarged, and the Duvernoy's gland produces a secretion with high proteolytic activity. Besides the ability of this large and powerful snake to inflict mechanical trauma, numerous cases of local envenomation and perhaps hypersensitivity have occurred, most of which have gone unreported. Prolonged, chewing bites may result in painful (sometimes extensive and persistent) swelling, as well as bruising. Nevertheless, the species is regularly kept as a pet, becoming increasingly popular in recent years. Manning et al. (1999) described a case in which an 18-year-old male