Greenbottle Blue Tarantula (Chromatopelma cyaneopubescens)

Physical description and identification

An adult greenbottle blue is unmistakable. The legs are metallic blue, the carapace is a blue-green that gave the spider its name — the colour of a greenbottle fly — and the abdomen is bright orange, often with darker central striping. It is the only species in its genus, so within the arid north of Venezuela there is nothing it can reasonably be confused with.

Adults

• Size: a mature female spans roughly 15 cm (6 in) across the legs; males are smaller and lighter at about 11.5 cm (4.5 in) and become leggy after their final moult.
• Colour: the blue is structural, produced by the microscopic architecture of the leg hairs rather than by pigment, which is why it shifts with the angle of light. Colour is at its most intense on a freshly moulted spider and dulls as the hairs wear.
• Eyes: eight small eyes clustered on a raised tubercle. Like other tarantulas it hunts by touch and vibration, not sight.
• Distinctive features: a New World tarantula, it carries urticating setae on the abdomen — barbed hairs it kicks into the air with the hind legs when alarmed. Long orange body hairs lie over them. Mature males have tibial hooks on the front legs and swollen pedipalps.

Eggs and egg sac

The female builds the sac deep in her silk tunnel, where it is hidden and insulated. A clutch is usually in the region of 100 to 200 small, round eggs. She guards and turns it for the six to eight weeks or so until the spiderlings emerge, and she is at her most defensive during this period.

Spiderlings

Juveniles look like a different species: pink or peach legs, a dark carapace and a dark abdomen crossed by rust-red stripes. The adult scheme appears gradually, blue first on the legs and then orange on the abdomen, so the colour of a young spider is a fair guide to how far through its growth it is. Growth is rapid for a tarantula — these are hungry spiderlings that moult often — with males maturing in roughly one and a half to two years and females in three to four.

The web and hunting

Few tarantulas spin as much silk. Under a bush, among exposed roots or in a rock crevice the greenbottle blue builds an extensive tunnel-and-funnel structure, thick, opaque and reinforced with debris, with sheets of webbing spreading out across the ground and up into the stems. In a desert that silk does three jobs at once: it holds a pocket of slightly more humid air, it shields the spider from sun and wind, and it acts as a genuine snare that tangles and signals passing insects. Compare it with the flat orb snares of other spider webs — this is a dense refuge with catching surfaces attached. The spider sits inside and rushes out when the silk twitches.

Where the greenbottle blue tarantula lives

Chromatopelma cyaneopubescens is endemic to the dry north of Venezuela, and is most closely associated with the Paraguaná Peninsula in Falcón state, with records in neighbouring arid country. This is thorn scrub and semi-desert: sandy or stony ground, cactus and dry shrubs, high daytime temperatures, low humidity and a short rainy season.

Within that landscape the spider is tied to shelter. It webs up the space beneath shrubs and tree roots, in rock crevices and in abandoned burrows rather than digging deep tunnels of its own, and the silk itself is what makes the habitat survivable. Because the species is restricted to a small and steadily developing region, and because it has long been collected for the pet trade, its wild status is worth watching even though it has not been formally assessed by the IUCN.

Are greenbottle blue tarantulas venomous?

Yes, like all spiders, but the venom is adapted to insects and is not medically significant for people. No deaths or serious systemic cases are on record, and a bite is usually compared to a bee sting with the addition of the mechanical injury from fangs several millimetres long.

The hairs are the real nuisance. As a New World tarantula it kicks urticating setae off its abdomen with the hind legs when it feels threatened, sending a cloud of barbed bristles into the air. On skin they produce itching, redness and a rash that can last for days; inhaled they irritate the airways; and in an eye they can lodge and cause a lasting inflammation that needs an ophthalmologist. Handle a shed skin or clean an enclosure and you are more likely to meet the hairs than the fangs, so wash your hands and keep them away from your face.

Can greenbottle blue tarantulas bite?

They can, but it is well down their list of options. The temperament is skittish rather than defensive: a disturbed greenbottle blue usually bolts into its web at high speed, and if that fails it turns and flicks hairs. Biting is a last resort for a spider that is pinned or squeezed.

A bite causes immediate sharp pain, minor bleeding, local redness and swelling that generally settles within a day or two. Wash the puncture with soap and water, use a cold pack and keep the area still. Seek medical care if pain worsens, if swelling spreads well beyond the bite, if the wound shows signs of infection, or if there is any sign of an allergic reaction. Do not cut, suck or heat the wound.

One real hazard has nothing to do with venom: this species is fast and easily startled, and a spider that bolts off a hand or a table can rupture its abdomen in the fall. That is the main reason it is a look-don't-touch animal.

Ecological importance and behaviour of the greenbottle blue tarantula

In a habitat with few large predators, this tarantula is a significant consumer of arid-land arthropods. It takes crickets, grasshoppers, roaches, beetles and other spiders, and reportedly kills scorpions that blunder into its silk. Its webbing concentrates that predation into a small area, so a mature spider works like a fixed trap at the base of a shrub.

Natural predators: spider-hunting wasps are the specialists, paralysing tarantulas and using them as living food for a single larva. Birds, lizards, snakes and small carnivores take spiders caught away from cover, and parasitic flies attack egg sacs.

Prey–predator dynamics: the bright colour is not a warning signal in any proven sense — inside the dark web it is barely visible, and the spider's protection is the silk, the retreat and the cloud of hairs. Its habit of staying in the web day and night is what keeps it out of reach of most predators.

Seasonal behaviour and lifespan: activity and breeding follow the rains. Mature males leave their webs to search for females and die within months of maturing, giving them about four years in total; females keep moulting and breeding and commonly reach twelve to fourteen. Adults moult roughly once a year, hanging on their backs inside the tunnel and remaining soft and vulnerable for several days.

Relationship with humans: the species is harmless to people and is one of the most commonly bred tarantulas in captivity, where it is kept dry and well ventilated with plenty of anchor points for silk. As with every showy tarantula, captive-bred animals — not wild-caught ones — are what keeps the pressure off a population confined to one small stretch of Venezuelan scrub.

Similar tarantulas and how to tell them apart

Quick facts

Did you know?

• Embrik Strand described the species in 1907; Günter Schmidt moved it into its own genus in 1995. Chromatopelma means roughly "coloured sole", from the Greek for colour and for the sole of the foot, and cyaneopubescens means "with blue down" — neither name means "beautiful blue", as is often repeated.
• The genus is monotypic: this one spider is the whole of Chromatopelma.
• The common name borrows from the greenbottle fly, whose metallic blue-green thorax is close to the colour of the tarantula's carapace.
• Its heavy webbing is a desert adaptation. Among tarantulas, species from dry country tend to web far more than species from rainforest, because silk holds moisture and shade around the spider.
• Spiderlings attack prey nearly as large as themselves, which is part of why they grow so fast.

In summary, the greenbottle blue tarantula is a spectacular, harmless spider from a small patch of Venezuelan desert. Recognise it by blue legs, a blue-green carapace and an orange abdomen, expect a wall of silk rather than a burrow, and remember that its defence is a cloud of itchy hairs, not a dangerous bite.