Cobras in the genus Naja are found in Asia and Africa. They are highly venomous and each species injects a cocktail of chemicals that have all kinds of different effects. For example, the effect might be slowing or speeding the heart rate, raising or lowering blood pressure, or preventing blood from clotting. So, if bitten, it's important to know which species was the culprit, so the right anti-venom can be adminstered.
Scientific name: Naja
The shading illustrates the diversity of this group - the darker the colour the greater the number of species. Data provided by WWF's Wildfinder.