Inland taipan
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 Ernst and Zug's published book "Snakes in Question: The Smithsonian Answer Book" from 1996. Bryan Grieg Fry, a prominent venom expert, 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, less lethal than other sea snakes such as the olive sea snake ("Aipysurus laevis") 0.09 mg/kg and the most toxic intramuscularly, recorded of the sea snakes – the black-banded robust sea snake ("Hydrophis melanosoma") 0.082 mg/kg. The black-banded robust sea snake has also been tested subcutaneously registering at 0.111 mg/kg. more than four times less toxic than the inland taipan's venom. In the LD subcutaneous test, it is actually Dubois' sea snake ("Aipysurus duboisii") which has the most toxic venom of any of the sea snakes tested, registering at 0.044 mg/kg. This is still nearly half as lethal as the inland taipan's venom.
Venom
Some 450 species of snake are venomous. Snake venom is produced by glands below the eye (the mandibular gland) and delivered to the victim through tubular or channeled fangs. Snake venoms contain a variety of peptide toxins, including proteases, which hydrolyze protein peptide bonds, nucleases, which hydrolyze the phosphodiester bonds of DNA, and neurotoxins, which disable signalling in the nervous system. Snake venom causes symptoms including pain, swelling, tissue necrosis, low blood pressure, convulsions, hemorrhage (varying by species of snake), respiratory paralysis, kidney failure, coma and death. Snake venom may have originated with duplication of genes that had been expressed in the salivary glands of ancestors.