Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This grade-Z zombie movie was made in 1964, but it was so bad they didn't release it until 1971. They tried several titles before this one, and then people complained that there is no skin-eating in the movie. But there are a few snakes and a snake-related plot, so it's not a complete bust.
Tom Harris (William Joyce) is a playboy adventure novelist who writes cheesy books with titles like "Hot Lips" and sits around swimming pools entertaining beautiful women. His publisher hustles him off to Voodoo Island in the Caribbean, owned by Lord Carrington, to force him to start writing his next novel. His publisher Duncan tells him "There's a large quantity of highly-poisonous snakes on the island. Lord Carrington has set up a foundation to perform experiments the snake venom. There's been a famous scientist there for years trying to find a cure for cancer."
When their small plane runs out of gas they are forced to land on the beach. Harris grabs a pistol and heads into the jungle to look for help. He sees a snake climbing on a tree and then another one. He shoots at a snake but apparently misses as we see it crawling on the ground afterwards. Then he escapes an attack by a bug-eyed zombie.
When the plane's passengers all get to the main compound, the main man Charles Bentley tells them that voodoo is practiced on the island, but it's harmless. Then we see local people playing drums and dancing at night. Their leader sings a song in Spanish about a serpent god, then they sacrifice a goat.
At the compound, Harris hooks up with Jeanine Biladeau (Heather Hewitt) the scientist's daughter. Her father won't let them see his laboratory, but they sneak off and watch him through a window as he milks the venom of several snakes into glass vials, then he force-feeds another one with a long tube slid into the snake's stomach. He puts a vial of venom into a very powerful oven-like device. (So powerful that at the end of the movie he uses the device to blow up the entire island.) Later he calls it "bombarded snake venom." When the venom is bombarded, he takes it into a room with sick men lying on beds. He injects one man with the venom and we see the man's face turn into the face of a bug-eyed zombie. It turns out he's not using the snake venom to cure cancer, he's making an army of indestructible zombies.
The first snake we see is a Yellow Ratsnake, common in Florida where this was filmed. The second snake is probably a racer, another common Florida snake. In the snake milking segment we see a cobra and a Cottonmouth and I think the snake being force-fed is a King Cobra. The snake handling was all done by Robert Haas, who had a Serpentarium in Miami at that time where you could watch him milk snakes. He's famous for having the Guinness world record for surviving the most venomous snake bites. He also lived to be 100 years old, so maybe there's something to this movie's idea of using snake venom to prolong life. I'm not going to try it, though. It could easily do the exact opposite.