The southern Pacific rattlesnake often has extremely neurotoxic venom similar to the Mojave rattlesnake. Credit: Audrey Snider-Bell via Getty Images

Rattlesnake venom is a complex blend of necrotic toxins designed to quickly disrupt blood coagulation and destroy tissue cells. This effective biological weapon comes at a major premium, however. Snakes must regularly replenish their venom reserves, which means they need to dole out just the right amount with each bite. Injecting too little venom into prey may allow their next meal to escape, while delivering too much can leave a rattlesnake defenseless against its own predators.

But that doesn’t mean rattlesnakes adhere to a one-bite-fits-all policy. According to researchers at California’s Loma Linda University, the amount of venom routinely varies by individual reptile.…