Snakes produce venom to defeat their prey and also to protect themselves against predators. According to Let’s Talk Science, it is produced by the salivary glands on the back of their heads and is released when they bite something.

A single dose of antivenom can cost up to $14,000 for a patient, Smithsonian Magazine reported. To produce it, researchers force a snake to bite the edge of a jar, dripping the venom. The amount of venom produced by a snake depends on the species and size; according to the University of Florida, the amount might vary from 1-850mg (“or more,” notes the university). The next step is to inject it inside an animal and later collect its antibodies.

Each species produces a different type of venom, and it can be used for treating pain, reducing blood clots, and even in beauty treatments. King cobra’s venom, for example, is rich in protein and is used in medications to treat chronic pain. It costs $153,000 per gallon, the second-most expensive venom on Earth (via Modern Farmer).

Coral and Brown snake venom costs $4,000 per gram. While Coral’s venom is used to produce antiviral and antibacterial medications, the Brown snake is used in antivenom production.