Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is a horror movie with some pretty nasty violence, but for me the most horrible thing is the terrible living conditions we see for the animals at a zoo in 1933. There's also too much forced comedy, but there are lots of scenes with snakes, so many, in fact, that I'm going to have to spoil the whole movie.
Lionel Atwill is nice and creepy as Eric Gorman, a rich guy who comes back from India with a lot of wild animals for a zoo. (Never mind that he's bringing chimpanzees and a "green mamba" and other animals that are only found in Africa.) He is very jealous of his wife Evelyn, played by the beautiful Kathleen Burke, so when he finds out she's planning to leave with another man he kills him with a severed snake head device full of mamba venom at a fancy publicity dinner at the zoo, and blames it on an escaped mamba, shutting down the zoo. When Evelyn finds the snake head device, she goes to the zoo to tell Dr. Woodford (Randolph Scott) the zoo's toxicologist, but Eric stops her and throws her into a pond full of alligators that eat her alive. Dr. Woodford finds out about Gorman's murders, so Gorman uses the snake head device to envenomate him, then he kills the "mamba" and lays it next to him, but it turns out Woodford made an antitoxin which is administered by his fiance and he survives. She alerts the police before Gorman can get away, so he releases lots of tigers and leopards from their cages as a distraction. (There are some shocking scenes of lions fighting leopards and other lions.) The big cats start to chase him so he ducks into a barred cage, not aware that there is a large hungry python inside. The python strikes and constricts him and we have the pleasure of watching him squeezed to death.
In Dr. Woodford's lab, we see a cage containing rattlesnakes of indeterminate species. Their rattling sounds are used for comic effect by the zoo's publicist, who thinks they are locusts, then is shocked by them. We also see shots of a rattlesnake being milked of its venom, but then we see the doctor handling a Boa Constrictor, which is standing in for a rattlesnake. In one scene Randolph Scott is holding an actual live rattlesnake (which is supposed to be the Green Mamba) and measuring the width of its fangs, but when he puts it back into its glass cage, they again used a harmless Boa Constrictor. (Filmmakers still don't believe the audience is capable of telling the difference between dissimilar species of snakes, so why should they have done so back in 1933?) The python that kills Gorman is a Reticulated Python, I think. You can see a thin string they used to pull the open-mouthed snake up to make it look like it was striking Gorman before it wrapped around him.