Melopoeus lividus, formerly Cyriopagopus lividus (Cobalt blue tarantula) 0.75"

Species Overview

Melopoeus lividus, commonly known as the cobalt blue tarantula, is a medium-sized fossorial tarantula native to Myanmar and Thailand, with a range likely extending into Cambodia. Juveniles and adult females are robust, with intensely iridescent cobalt- to violet-blue legs; the color is strongest on the femora and tibiae, while the remaining segments often appear slate blue or blue-gray. The chelicerae bear contrasting silver-gray hairs, and the carapace ranges from silvery or greenish gray to dark olive- or brownish gray, usually with a paler margin and fine pale to copper-colored hairs along the radiating grooves. The abdomen varies from slate blue-gray to dark brown or nearly black and may show a darker longitudinal median field with faint paired spots or chevrons. Coloration is generally most vivid following a molt and shifts substantially with lighting. Immature males resemble females, but mature males become much slimmer and proportionally longer-legged, with a copper-brown carapace displaying a bronze sheen and a pale tan to bronze-brown abdomen. Their legs combine nearly black to dark chocolate femora with dusty violet-gray, mauve-brown, or reddish-brown distal segments that may darken with age; narrow pale copper to pinkish-tan longitudinal lines extend across several segments.

In captivity, M. lividus is an accomplished excavator that normally establishes a deep, silk-lined burrow and may incorporate much of the surrounding substrate into its retreat. Individuals often remain completely concealed during the day but commonly wait just inside the entrance after dark and respond rapidly when they detect prey. Once a suitable burrow and moisture gradient have been established, this is a hardy species with straightforward environmental requirements. Its speed and defensive response when exposed, however, require deliberate enclosure maintenance, particularly with larger specimens. Like other Old World species, M. lividus lacks urticating hairs and relies primarily on speed, retreat use, and defensive displays when disturbed.

• Common Name: Cobalt blue tarantula
• Native Range: Myanmar and Thailand; likely extending into Cambodia
• Life Habit: Fossorial
• Adult Size: 5–6 inches in diagonal leg span
• Lifespan: Males 2–3 years; females 10–15+ years under optimal conditions
• Temperament: Fast and defensive when exposed
• Care Difficulty: Easy to Moderate

Melopoeus lividus Care

Melopoeus lividus adapts well to captivity when provided with deep, compactable substrate, a moderate humidity gradient, and adequate ventilation. Design the setup around the species’ fossorial behavior, with most of the enclosure height devoted to substrate and only limited open space above it. A starter burrow or partially buried piece of cork bark can encourage excavation. Once the tarantula has established a permanent retreat, minimize unnecessary disturbance.

• Enclosure: 2.5” cube or similar for spiderlings, upgraded as needed with growth; 10” x 10” x 10” or larger for adults
• Substrate: Provide a deep layer of compactable, moisture-retentive substrate that holds its shape when excavated. Coconut fiber, peat moss, topsoil, or similar substrates work well, and a small clay component can improve burrow stability. Devote most of the available enclosure height to substrate.
• Temperature: 72–82°F
• Humidity: Moderate ambient humidity is generally sufficient. Approximately 50% of the substrate, particularly the lower layers, should retain moisture to provide a humidity gradient while allowing the remaining substrate and most of the surface to stay drier. Avoid consistently saturated substrate, excessive condensation, and stagnant air.
• Diet: Crickets, cockroaches, and other appropriately sized feeder insects
• Feeding: Spiderlings can be offered appropriately sized prey once or twice weekly. Juveniles and adults are typically fed every 7–14 days, with feeding frequency adjusted based on prey size, growth rate, and the condition of the individual animal.
• Water: Moisten part of the substrate as needed and provide water droplets on enclosure surfaces and webbing for spiderlings; larger specimens should have access to a water dish.
• Routine Maintenance: Remove uneaten prey, monitor moisture levels, and spot-clean when necessary.

Natural History

Melopoeus lividus was described by British arachnologist Andrew M. Smith in 1996 under the name Haplopelma lividum. The male holotype and female paratypes originated from Kawkareik in present-day Kayin State, Myanmar, near the border with Thailand. The species epithet derives from the Latin lividus, a term applied to bluish, leaden, or bruise-colored shades, and refers to the coloration for which the species is known.

Smith and Michael Jacobi transferred the species to Cyriopagopus in 2015, and Cyriopagopus lividus subsequently became the name most familiar to contemporary hobbyists. In 2026, Smith, Bexell Ayyachamy Daniel, and Benoît Vignaud restored Melopoeus as a valid genus and transferred the species to its currently accepted combination, Melopoeus lividus. The former names Haplopelma lividum and Cyriopagopus lividus therefore refer to the same species and remain widespread in older literature, care information, and captive breeding records.

The formally documented native range includes Myanmar and Thailand, but the species likely extends into Cambodia as well. A 2026 checklist records M. lividus from Kayin State and Tanintharyi Region in Myanmar, while photographic and field records in Thailand include Phetchaburi Province. Citizen science observations from Cambodia have also been identified as this species, including a well-localized individual photographed at a heavily silk-lined retreat near Thma Bang in the Cardamom Mountains region. These spiders closely resemble M. lividus, making a Cambodian range extension plausible; however, confirmation through examination of diagnostic morphology is still lacking, and other closely related Melopoeus species occur in Cambodia. 

Wild M. lividus have been documented in burrows excavated into level ground and roadside embankments within moist forest landscapes. These permanent silk-lined retreats allow the tarantula to remain protected below ground during the day and detect passing prey from near the entrance after dark. The extensive burrowing and secretive behavior observed in captivity therefore closely reflect the species’ natural ecology.