When its melanistic, of course!
The above is a Juvenile red-necked keelback (Rhabdophis subminiatus), and so is the snake below.
So how can they be so different? Well, its like white tigers, or Albino snakes, or many other breeds that are missing colours, and that quite frankly do not exist very often in the wild. If they do, their chances of survival or mating are not great, but often they are ascribed great powers or revered, like the whitish coated brown bears in the USA. So back to my little snake....this was found wild in Hong Kong by Mr Dan, the snake man. It is a very rare “morph”…(not a mutant!).ie change in colouration/pigmentation. Ok, get ready for some science: As to the type of morph….The prefix referring to red is "ery", therefore snakes without red are routinely called Anerythristic. While this is technically correct for this snake, it is more properly termed axanthic as it is missing the entire complex of xanthophores which control both yellow and red pigment. phew…but this is a strange one, as it isn't just axanthic - because the normal coloration is a green body - and if you take yellow away from green, you get blue. So a red-necked keelback that was just axanthic should be blue in coloration. Obviously this isn't, and it is black - so melanistic would also be a fitting term (a high production of melanism / i.e., black pigment).
sooooooo, after all that, we have a Melanistic red-necked keelback. (Thank you Kevin Messenger for helping on this).
The red-necked keelback is also a very rare type of snake for another reason...do you know why? For the answer see the blog on red-necks.