Size and growth
Adult Aphonopelma bicoloratum reach about 13–15 cm (5–6 in) and are very slow growers. Adult Aphonopelma chalcodes reach about 13–15 cm and are very slow growers. That affects how quickly Mexican Blood Legs and Arizona Blonde Tarantulas move through sling and juvenile enclosure sizes.
Do not use size alone to estimate age in either Aphonopelma bicoloratum or Aphonopelma chalcodes. Sex, feeding and individual variation can change the pace of growth even when two spiders began at a similar size.
Enclosure and lifestyle
Mexican Blood Legs are terrestrial, while Arizona Blonde Tarantulas are terrestrial. Build the Aphonopelma bicoloratum enclosure for a terrestrial spider and the Aphonopelma chalcodes enclosure for a terrestrial spider instead of assuming two tarantulas need the same shape of setup.
For Aphonopelma bicoloratum, substrate depth, retreat position and usable space should match its terrestrial lifestyle. Apply the same rule separately to Aphonopelma chalcodes; the enclosure should make normal behaviour easy rather than forcing either species into a generic layout.
Temperature, water and moisture
A practical temperature range for Aphonopelma bicoloratum is 20–25°C; for Aphonopelma chalcodes, it is 18–26°C. Stable room conditions are more useful for both species than chasing small fluctuations within those ranges.
For Aphonopelma bicoloratum, keep a mostly dry setup with with a water dish; avoid chronic wetness. For Aphonopelma chalcodes, keep a mostly dry setup with surface conditions with clean water available; modest moisture for smaller slings. In both enclosures, keep fresh water available and adjust substrate moisture to how quickly the setup actually dries.
Temperament and maintenance
Aphonopelma bicoloratum is a New World species, while Aphonopelma chalcodes is a New World species. That background is useful when planning maintenance, but individual Mexican Blood Legs and Arizona Blonde Tarantulas can still differ noticeably in speed and defensiveness.
With both Aphonopelma bicoloratum and Aphonopelma chalcodes, locate the spider before opening the enclosure, use long tools when they make the job safer and keep a catch cup ready for rehousing. Handling is not required for routine care.
Male and female lifespan
Male Aphonopelma bicoloratum generally live roughly 5–7 years, while females can live 20 years or more. Male Aphonopelma chalcodes generally live roughly 5–8 years, while females can live 20–30+ years.
Those lifespan ranges make sex particularly relevant when comparing Aphonopelma bicoloratum with Aphonopelma chalcodes. A confirmed female of either species is normally a much longer commitment than a mature male, and the exact age of an older juvenile may be impossible to know.
UK availability and trade notes
In the UK hobby, Aphonopelma bicoloratum is currently classed as uncommon, while Aphonopelma chalcodes is classed as common. Stock changes between specialist sellers, captive-produced batches and show weekends, so availability should be checked at the time of purchase.
For records and purchases, use the scientific names Aphonopelma bicoloratum and Aphonopelma chalcodes as the main identifiers. Current trade notes list Aphonopelma bicoloratum as 'Check current CITES rules before cross-border trade' and Aphonopelma chalcodes as 'Not listed', so check current requirements before any international movement where controls may apply.
Practical difference in day-to-day care
The practical difference between Aphonopelma bicoloratum and Aphonopelma chalcodes comes from the combination of lifestyle, adult size, growth and moisture needs. Those factors change how much substrate, vertical space and maintenance access each enclosure needs.
Whichever species you keep, let the individual spider settle into an enclosure designed for its own biology. That applies equally to Aphonopelma bicoloratum and Aphonopelma chalcodes: fresh water, secure housing and patient observation matter more than trying to make the two species behave the same way.