Venomous snake
Belcher's sea snake ("Hydrophis belcheri"), which many times is mistakenly called the hook-nosed sea snake ("Enhydrina schistosa"), has been erroneously popularized as the most venomous snake in the world, due to the first edition of Ernst and book, "Snakes in Question: The Smithsonian Answer Book", published in 1996.
Prominent venom expert Associate Professor Bryan Grieg Fry has clarified the error: "The hook nosed myth was due to a fundamental error in a book called "Snakes in Question". In there, all the toxicity testing results were lumped in together, regardless of the mode of testing (e.g., subcutaneous vs. intramuscular vs. intravenous vs. intraperitoneal). As the mode can influence the relative number, venoms can only be compared within a mode. Otherwise, it's apples and rocks." Belcher's sea snake's actual LD (recorded only intramuscularly) is 0.24 mg/kg and 0.155 mg/kg. Studies on mice and human cardiac cell culture show that venom of the inland taipan, drop by drop, is the most toxic among all snakes.
Rattlesnake
The venom is hemotoxic, destroying tissue, causing necrosis and coagulopathy (disrupted blood clotting). In the U.S., the tiger rattlesnake ("C. tigris") and some varieties of the Mojave rattlesnake ("C. scutulatus") also have a presynaptic neurotoxic venom component known as Mojave type A toxin, which can cause severe paralysis. Although it has a comparatively low venom yield, the venom toxicity of "C. tigris" is considered to be among the highest of all rattlesnake venoms, and among the highest of all snakes in the Western Hemisphere based on studies conducted on laboratory mice. "C. scutulatus" is also widely regarded as producing one of the most toxic snake venoms in the Americas, based on studies in laboratory mice.