The Goliath birdeater (Theraphosa blondi) belongs to the tarantula family Theraphosidae. Found in northern South America, it is the largest spider in the world by mass – 175 g (6.2 oz) – and body length – up to 13 cm (5.1 in) – but it is second to the giant huntsman spider by leg span. It is also called the Goliath bird-eating spider; the practice of calling theraphosids "bird-eating" derives from an early 18th-century copper engraving by Maria Sibylla Merian that shows one eating a hummingbird. Despite the spider's name, it only rarely preys on birds.