Theraphosa blondi is a bulky mygalomorph of the Guiana Shield, with a leg span approaching 28 centimetres and recorded masses near 175 grams, which makes it the heaviest spider known. It lives in a silk-lined burrow in lowland rainforest and hunts on foot after dark.
The common name traces to a plate published by Maria Sibylla Merian in 1705 showing a large tarantula feeding on a hummingbird, not to ordinary behaviour. Recorded diets are dominated by insects, earthworms and amphibians, with the occasional small snake or rodent. Vertebrate prey is opportunistic, and birds are rare.
Its first defence is not a bite. A disturbed animal rubs its hind legs against the abdomen to fling urticating setae, barbed hairs that irritate skin, eyes and airways, and it stridulates audibly with the bases of its legs. The venom is not regarded as dangerous to people; the hairs cause most of the trouble that keepers report.