--- title: "Chilean Rose Tarantula (Grammostola rosea) | AnimalTracks.wiki" description: "The desert tarantula with no extensor muscles at two leg joints, and a metabolism that slows when food runs short." image: "https://animaltracks.wiki/images/animals/tarantula-1.webp" published: "2026-08-30" updated: "2026-09-28" --- # Chilean Rose Tarantula (*Grammostola rosea*) > **Status**: Checked against 6 sources, listed under Sources below. > **Tagline**: The desert tarantula with no extensor muscles at two leg joints, and a metabolism that slows when food runs short. > **Soundtrack Vibe**: Slowcore & Minimal Indie // Duster, "Inside Out" > **Soundtrack Links**: [Spotify](https://open.spotify.com/track/6WlmEymaXKMRs3D2c4j6os) > **Vibe Match**: Slow, sparse songs for a spider whose metabolic rate is 63 percent of the value expected for other spiders of its body mass, and drops further when it is deprived of food. ## Biological Superpowers & Stats - **Taxonomy**: *Grammostola rosea* - **Danger Level**: Low - **Conservation Status**: Not Evaluated ([IUCN Red List](https://www.iucnredlist.org/)) - **Superpower**: No extensor muscles at two leg joints, where blood pressure may work against the flexors - **Habitat**: Desert and scrub habitats across Chile, Argentina, and Bolivia - **Diet**: A variety of invertebrates, plus small vertebrates such as mice, frogs, and lizards - **Tags**: arachnid, desert, nocturnal, carnivore, venomous ## Natural History & Behavior ## Two Joints Without Extensors Spiders have flexor muscles to pull their legs in, but a 1957 study of spider leg muscles confirmed that they have no extensor muscles at two of their leg joints. The study raised the possibility that the flexors there work against the spider's own blood pressure, so that haemolymph, the fluid inside its body, would do the straightening a muscle normally does. > **A Tiny Oxygen Gradient** A Chilean rose tarantula's lungs are so refined that a difference in oxygen partial pressure of just 0.12 to 0.16 kilopascals across the lung barrier covers its resting oxygen needs, against about 7.5 kilopascals that mammals require. ## Built to Wait, Built to Molt This is a medium-sized tarantula that lives on the ground. Females average a leg span of 12 to 13 centimeters and males about 9 centimeters, though males have proportionally longer legs. Females live up to twenty years in human care, far outliving males, which die within a few months of mating. Among spiders it counts as large, at more than 14 grams. Its metabolic rate is 63 percent of the value expected for other spiders of its body mass, and researchers have recorded that rate dropping at 30°C when it is deprived of food. To grow, it must go through several molts, and spiderlings molt five or six times in their first year. The species is native to desert and scrub habitat across Chile, Argentina, and Bolivia, where it hunts at night. It feeds on a variety of invertebrates as well as small vertebrates such as mice, frogs, and lizards, relying on its size to subdue them. ## The Bristle Defense It can throw irritating hairs from its body in defense, and doctors studying tarantula bites note that New World species like this one typically cause injuries to people through their urticating hairs, which can penetrate skin and mucous membranes and cause local tissue reactions. The hairs appear rose-colored on Grammostola rosea, which is where the "Chilean rose" name comes from. ## Forty-Eight Toxin-Like Peptides Scientists sequencing genes from Grammostola rosea venom glands predicted forty-eight new toxin-like peptides from the sequences. One of them, GTx1-15, inhibits one voltage-dependent calcium channel and two voltage-dependent sodium channels. Doctors reporting a bite from this species that left a woman with weeks of cramping note that trouble with both kinds of channel could affect muscle contractions. ## Frequently Asked Questions ### How slow is a Chilean rose tarantula's metabolism? Measured by oxygen use, it burns energy at about 63 percent of the rate expected for a spider of its body mass. Deprive it of food and the rate falls further, a metabolic depression researchers have reported at 30°C. *(Source: [Canals, Veloso & Solís 2015]())* ### Is a Chilean rose tarantula dangerous to people? Bites from this species are rare and poorly described in the medical literature. Case reports of tarantula bites in adults commonly describe local tissue damage and pain, but doctors have published a case where a Grammostola rosea bite on a woman's forearm caused severe local muscle cramping within hours, and the cramping went on for four weeks after she left hospital. How tarantula venom causes muscle spasms is not well understood. *(Source: [Gooley et al. 2025]())* ### Does a Chilean rose tarantula have muscles to straighten its legs? Not at every joint. A 1957 anatomical study of spider legs confirmed that spiders lack extensor muscles at two leg joints, leaving only flexors, the muscles that pull a limb in. The author suggested those flexors may work in opposition to the spider's blood pressure, which would then push the leg straight. *(Source: [Parry 1957]())* ## Sources 1. [Chilean rose tarantula. Smithsonian's National Zoo and Conservation Biology Institute.]() 2. [Parry (1957). Spider Leg-muscles and the Autotomy Mechanism. Journal of Cell Science.]() 3. [Canals, Veloso & Solís (2015). Adaptation of the spiders to the environment: the case of some Chilean species. Frontiers in Physiology.]() 4. [Kimura, Ono & Kubo (2012). Molecular Cloning and Sequence Analysis of the cDNAs Encoding Toxin-Like Peptides from the Venom Glands of Tarantula Grammostola rosea. International Journal of Peptides.]() 5. [Kimura (2021). Stability and Safety of Inhibitor Cystine Knot Peptide, GTx1-15, from the Tarantula Spider Grammostola rosea. Toxins.]() 6. [Gooley et al. (2025). A Case Report of Delayed, Severe, Paroxysmal Muscle Cramping after Chilean Rose Tarantula (Grammostola rosea) Envenomation. Clinical Practice and Cases in Emergency Medicine.]() *Published August 30, 2026. 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