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.
List of medically significant spider bites
The Australian funnel-web spiders, such as the Sydney funnel-web spider "Atrax robustus" (a mygalomorph spider not to be confused with the araneomorph funnel-weaver or grass spiders) are regarded as among the most venomous in the world. They react vigorously to threats and, reputedly, will more often attempt to bite than run away. "A. robustus", a large black spider, is found within a radius of about 100 km from Sydney. Its venom contains a compound known as atracotoxin which is highly toxic to primates. Approximately 10% of bites lead to serious symptoms for a total of 3-4 severe envenomations annually.