There are over 3,000 snake species worldwide, with about 600 being venomous. Venomousness is measured using median lethal dose (LD50) test. Snakes are categorized based on venom amount and potency
Venomous animals actively inject toxins through bites or stings. Venoms can range from mild discomfort to death. Only medically significant venomous animals are included
Latrodectus genus contains 34 species of spiders known as true widows. Females are dark brown with reddish hourglass markings on abdomen. Males have red or red-white markings on dorsal abdomen. Body size ranges from 3-10 mm, females up to 38 mm including legs
Most dangerous snakes are venomous, except for harmless garter snakes. Amphibians carry toxins on skin and tissues, including deadly poison dart frogs. Spiders, lizards, bees, ants, and wasps are venomous. Platypus has venomous spurs on ankles connected to thigh glands. Cnidarians have nematocysts containing barbed threads with toxins
Box jellyfish's tentacles can reach 3m long and cause 40-100 deaths annually. Beaked sea snake delivers venom causing paralysis, especially respiratory failure. Cone snails use venom-filled harpoons, with around 30 recorded deaths. Stonefish's dorsal spines deliver venom causing limb swelling and necrosis. Blue-ringed octopus produces tetrodotoxin causing rapid paralysis
Black widows are venomous spiders found worldwide. Females reach up to 1.5 inches long, males are 1/4 inch. Females have hourglass-shaped red markings on abdomen. Males have reddish-brown legs and white abdomen. Both sexes have bristles on back legs for web wrapping