Can you tell whether a snake is venom snake or not from the look without knowing its exact species?
I used to read it somewhere that claim if the snake's head look like an angle, it is a venom snake. Lately I have seen photos of obviously not venom snake pet, they have what was described "angle" like heads. Now I am clueless.
The "trianglular shaped head" theory, taught to kids in America commonly, mostly applies to North American Crotalinae, (Rattlesnakes, cottonmouths, and copperheads.) They account for most envenomations in the U.S. The coral snakes are the only other venomous snake in the U.S., and there are far less bites, and less chance of envenomation if you are bitten. There are many species of nonvenomous snakes that do have a similar shaped head. Long story short, no, around the world, you would have to know the species. Boomslangs, australian brown snakes, & cobras cause allot of deaths, and do not have a triangular shaped head.
Cobra is easy to identify with their wide neck. Rattlesnakes also have that dead giveaway characteristic nobody should miss.
Other snakes, not so much. I guess it is important to know the actual species, but there are just so many of snake species out there. No way for ordinary people to learn all of them.
I love reptiles, and I know allot of them, and there are still things I have to look up, though there are allot of common characteristics in certain families and genera that can be a good place to start. I would say it is a good idea to know any potentially venomous reptiles in your area.
Some people think that only venomous snakes have "pits" in their heads, as they associate it with the term "pit viper". This cannot be used, as there are venomous snakes that do not have thermal pits, as well as non-venomous snakes that eat endothermic (warm blooded) prey, and thus use pits for hunting.
I do not have good eye sight. It wouldn't matter to me. Unless the snake has huge identifiable characteristics as a certain species, I wouldn't be able to tell pit or not, triangle head or not. I can't see that clearly.