The Goliath birdeater (Theraphosa blondi) is an arachnid, or spider, belonging to the tarantula family, Theraphosidae. It is considered to be the second largest spider in the world (by leg-span, it is second to the giant huntsman spider), and it may be the largest by mass. These spiders can have a leg span of up to 30 cm (12 in) and can weigh over 170 g (6.0 oz).