Saw this on my driveway. [Tampa Florida]
By - Bigscag
Banded Watersnake, *Nerodia fasciata*, !harmless.
Banded Watersnakes *Nerodia fasciata* are medium (90-110 cm record 158.8 cm) natricine snakes with keeled scales often found in and around water. They are commonly encountered fish and amphibian eating snakes across much of eastern North America.
*Nerodia* watersnakes may puff up or flatten out defensively and bite. They secrete a foul smelling substance from the cloaca called musk and can deliver a weak anticoagulant venom used in prey handling from the back of the mouth, but are not considered medically significant to humans - bites just need soap and water.
Found throughout southeastern North America, it is replaced in the North by, and likely exchanges genes with, the Common Watersnake *Nerodia sipedon*. Banded Watersnakes have even, connecting bands across the top of the snake all the way down the body. In common watersnakes *N. sipdeon*, bands typically break up or become mismatched after the first third of the body. The "confluens" color pattern is somewhat of an exception to the even banding rule, but isn't often confused with other species as it is rather distinctive.
*Nerodia fasciata* along the Gulf and Atlantic coasts in the Southeastern US also exchange genes along environmental ecotones with Saltmarsh Snakes *Nerodia clarkii*.
[Range Map](http://snakeevolution.org/rangemaps/Nerodia_fasciata.jpg) | [Relevant/Recent Phylogeography - Unpublished](http://stars.library.ucf.edu/cgi/viewcontent.cgi?article=3823&context=etd)
This genus, as well as this species specifically, are in need of revision using modern molecular methods. Unfortunately what we know about this species is unpublished, but it's likely that it is composed of three species - a peninsular Florida species, a species west of the Mississippi River, and a continental eastern North American species.
Like many other animals with mouths and teeth, non-venomous snakes can use them to bite in self defense. These animals are referred to as 'not medically significant' or traditionally, 'harmless'. Bites from these snakes benefit from being washed and kept clean like any other skin damage, but aren't often cause for anything other than basic first aid treatment. Some snakes use venom from front or rear fangs as part of prey capture and defense. This venom is not always produced or administered by the snake in ways dangerous to human health, so many species are venomous in that they produce venom, but considered harmless to humans in most cases because the venom is of low potency, and/or otherwise administered through grooved rear teeth or simply oozed from ducts at the rear of the mouth. Species like Ringneck Snakes *Diadophis* are a good example of mildly venomous rear fanged dipsadine snakes that are traditionally considered harmless or not medically significant. Many rear-fanged snake species are harmless as long as they do not have a chance to secrete a medically significant amount of venom into a bite; [severe envenomation can occur](https://pubmed.ncbi.nlm.nih.gov/23800999) if some species are [allowed to chew on a human](https://www.sciencedirect.com/science/article/abs/pii/S004101011831016X) for as little as 30-60 seconds. It is best not to fear snakes, but use common sense and do not let any animals chew on exposed parts of your body. Similarly, but without specialized rear fangs, gartersnakes *Thamnophis* ooze low pressure venom from the rear of their mouth that helps in prey handling, and are also [considered harmless](https://cityroom.blogs.nytimes.com/2012/06/05/theres-no-need-to-fear-that-garter-snake/). Even large species such as *Malayopython reticulatus* [rarely obtain a size large enough to endanger humans](https://www.pnas.org/content/pnas/108/52/E1470.full.pdf) so are usually categorized as harmless.
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