Amazon Ribbed Tarantula

The Amazon Ribbed Tarantula (Iridopelma hirsutum) is a medium Brazilian arboreal — not a dwarf, despite sometimes being sold as one — with a leggy, iridescent build and understated shimmer. A fast, skittish tree spider that threat-poses readily and, unusually, carries Type II urticating hairs that transfer by contact rather than being kicked. Height, airflow and light misting keep it happy. An engaging, active arboreal for the intermediate keeper who wants something a little off the usual pinktoe path.

Temperature75–82°F (24–28°C) — warm room with a gradient (top warmest). Steady tropical warmth; no hot basking lamps.
HumidityDamp but ventilated, 70–80%. Keep the lower substrate lightly damp and the top dry, mist lightly, and pair with strong cross-ventilation — standard arboreal moisture-plus-airflow. Don't saturate.
Adult sizeA medium-sized tarantula: adults reach 4–5 inches across the legs (diagonal leg span). A steady grower at a moderate pace.
LifespanFemales roughly 10–12 years; mature males 3–4 years.

Enclosure

Tall arboreal — height over floor, a vertical cork slab and branches for climbing and web anchoring, strong cross-ventilation. It builds silk retreats up high. Front-opening and secure (it's fast and skittish). Slings in tall, airy vials.

Substrate & water

1–2 inches of coco/topsoil at the base, lower layer lightly damp and top dry, with a water dish. Vertical structure is the priority; the substrate holds humidity. Ventilate the base.

Feeding

A keen, quick feeder that ambushes from its web. Prey to abdomen size — fruit flies/pinheads for slings, crickets for adults; slings every few days, adults weekly. Remove uneaten prey promptly.

Temperament & defenses

Intermediate: fast, skittish, and quick to threat-pose — jumpier and feistier than a pinktoe. Its Type II urticating hairs are unusual in transferring by contact rather than being kicked, so avoid touching the spider or freshly-webbed surfaces and wash up after enclosure work. Venom mild. A display-and-observe species.

Keeper’s notes

An underrated medium arboreal for a keeper wanting something beyond the pinktoes — that iridescent, ribbed look is subtle but lovely, and it's an active, engaging tree spider. Just know it's genuinely 'not a dwarf' (give it proper arboreal room) and that its contact-transfer hairs mean hands-off is the rule. Height, airflow, a light misting, and a vertical retreat, and it thrives.