Mexican Orange Beauty Tarantula (Brachypelma baumgarteni)

Physical description and identification

The Mexican orange beauty is one of the easiest Mexican tarantulas to name once you know where to look: at the carapace. A dark, almost black central disc is surrounded by a broad ring of orange to golden hairs, giving the front of the spider a halo that nothing else in its range quite matches. Behind it the abdomen is jet black, so the orange stays concentrated in the front half of the animal.

Adults

• Size: a diagonal leg span of roughly 11–16 cm (about 4.3–6.3 inches), placing it in the medium-to-large bracket. Females are heavier and thicker-legged; mature males are longer-limbed and considerably lighter.
• Colour: black disc with an orange ring on the carapace, jet-black abdomen, and legs that are black on the feet and lower segments and orange-red from the tibia inwards toward the body. The result is a black spider with orange thighs and an orange collar.
• Other features: dense bristles cover the body and legs, including the barbed urticating setae of the abdomen. Like every theraphosid it has two pairs of book lungs, paired downward-striking fangs and eight small eyes on a low mound. Mature males show tibial hooks on the front legs and swollen, club-shaped pedipalps.

Eggs and egg sac

The eggs are yellow and the female wraps them in a thick silk cocoon almost as soon as they are laid. She keeps the sac deep inside her burrow, turning it regularly and defending the entrance, and feeds little during the several weeks of incubation.

Spiderlings

Newly emerged spiderlings have a pale, almost transparent abdomen and none of the adult pattern. The orange ring and orange leg segments appear gradually, one moult at a time, over the first few years. Growth is slow even by tarantula standards, and slings disperse from the mother's burrow within a few weeks of emerging.

The web and hunting

This species builds no capture web. It is a terrestrial ambush hunter that digs a burrow, lines the wall with silk and lays a thin mat of threads across the entrance to sense approaching footsteps. Prey is grabbed at the doorway after dark and dragged inside. Silk is also used to seal the burrow before a moult and to build the egg sac — a floor, a door and a cradle rather than a snare, unlike the structures in our guide to spider webs.

Where the Mexican orange beauty tarantula lives

Brachypelma baumgarteni is endemic to the Pacific coast of Michoacán in western Mexico. The known range is a strip of coastal lowland and foothill bounded roughly by the Sierra Madre del Sur and the Balsas river basin — a very small area for a large, slow-breeding animal, and the central fact of its conservation status.

The habitat is tropical deciduous forest and adjacent thorn scrub: hot, strongly seasonal country with heavy summer rains and a long dry winter in which most of the trees drop their leaves. The tarantula digs or occupies burrows on well-drained slopes, among tree roots and beneath rocks, and spends the dry season sealed underground. Nearly all surface activity happens during and just after the rains, at night.

Its range does not overlap the highland Mexican golden red rump of Guerrero and Morelos, and it sits south of the Mexican pink of the Nayarit–Jalisco coast, although it is close enough to the Mexican red knee of Michoacán and Colima that the two can be found in the same state.

Are Mexican orange beauty tarantulas venomous?

Yes, like every tarantula, but the venom is mild and not medically significant to people. A bite is usually described as comparable to a bee sting: sharp local pain, redness and swelling that settle within hours to a day or two. No deaths, tissue necrosis or systemic poisoning are on record for this or any other New World theraphosid.

The abdomen is the part that actually injures people. Like its relatives, this species carries urticating setae — barbed hairs kicked off with the hind legs when it is alarmed. They lodge in skin and produce an itchy, burning rash lasting several days, and if they reach the eyes they can embed in the cornea and cause an inflammation that needs an ophthalmologist rather than home treatment. Never put your face over a disturbed tarantula, and wash your hands afterwards.

Can a Mexican orange beauty tarantula bite?

It can, as a defence, but it is a calm species that plainly prefers to avoid conflict. The usual sequence is to retreat, then to rear up and flick hairs, and only to strike if pinned, squeezed or grabbed. Because the fangs are several millimetres long, most of the injury is mechanical: two deep punctures, local pain and swelling, resolving within a day or two.

Wash a bite with soap and water, apply a cold pack and take an ordinary painkiller if you need one, then keep the punctures clean while they heal. Seek medical attention if the pain escalates rather than fading, if the area becomes hot and spreading, or if you develop a widespread rash, faintness or difficulty breathing, which point to an allergic reaction rather than to the venom. Do not cut, suck or apply chemicals to the wound.

Ecological importance and behaviour of the Mexican orange beauty

Solitary and strictly nocturnal, the Mexican orange beauty spends daylight underground and emerges at the burrow mouth after dark. It takes cockroaches, crickets, locusts, beetles and other large ground insects, with small lizards taken occasionally. Since one adult may hold the same burrow for a decade or more, a population applies constant, long-term pressure on the invertebrates of the forest floor and keeps leaf-eating insects in check.

Natural predators: birds of prey, coatis, skunks and snakes take adults, and tarantula hawk wasps of the genus Pepsis paralyse a spider and lay an egg on it, the larva consuming the still-living host. Spiderlings are eaten by ants, scorpions and other spiders — see what eats spiders. Urticating hairs deter some attackers but do nothing against a wasp.

Seasonal behaviour: mature males abandon their burrows during the rains and wander in search of females, which is when almost every wild sighting happens. A male rarely survives a year past his final moult; a female may still be breeding twenty years after hers.

Relationship with humans: the species is not aggressive and poses no threat, but it has become desirable in the exotic pet trade for its colour and calm temperament, and that demand is a problem for an animal with such a small range. Like the entire genus Brachypelma it is listed on CITES Appendix II, so international movement requires permits and documented legal origin; habitat clearance along the Michoacán coast compounds the pressure.

Similar spiders and how to tell them apart

Quick facts

Did you know?

• The British arachnologist Andrew M. Smith described the species in 1993 from the coast of Michoacán; the name honours the collector Baumgarten.
• It looks superficially like several colourful Mexican tarantulas, but anatomy and DNA place it closest to the Mexican fireleg and the Mexican flame knee, in the group that kept the name Brachypelma after the 2020 revision.
• That revision, by Mendoza and Francke, moved the plain black “red rump” species into a new genus, Tliltocatl, from the Nahuatl words for black and spider — which is why some tarantulas that used to share this animal's genus no longer do.
• Urticating hairs are unique to New World tarantulas; the African and Asian species have none and rely on speed and a much more painful bite.
• Every Brachypelma species has been on CITES Appendix II since 1994, making them among the first spiders anywhere to receive international trade protection.

In summary, the Mexican orange beauty tarantula is a calm, slow-growing burrower whose orange-ringed carapace and orange upper legs make it unmistakable in the dry forests of coastal Michoacán. It is no danger to people — its hairs are the only thing to avoid — and the small size of its range, not its bite, is what should concern anyone reading about it.