When it comes to tarantulas, Brachypelma species are among the most popular choices for pet owners due to their docile nature and striking appearances. Two species that often cause confusion are Brachypelma smithi (commonly known as the Mexican Red-knee Tarantula) and Brachypelma hamorii (previously referred to as Brachypelma smithi but now classified as a distinct species). Both species belong to the same genus, and while they share some similarities, they have notable differences in size. In this article, we will compare the sizes of Brachypelma smithi and Brachypelma hamorii, examining their leg spans, body lengths, and other physical characteristics.
Overview of Brachypelma smithi and Brachypelma hamorii
Both Brachypelma smithi and Brachypelma hamorii are native to Mexico. They are often confused with one another due to their similar appearance. The key difference between the two species lies in their leg span and body size. While Brachypelma smithi is typically a smaller species, Brachypelma hamorii can grow significantly larger.
Physical Size of Brachypelma smithi
The Brachypelma smithi, also known as the Mexican Red-knee Tarantula, is a medium-sized tarantula species. Adults generally have the following measurements:
Leg Span: The typical leg span of an adult Brachypelma smithi ranges from 5 to 6 inches (12 to 15 cm). This makes them one of the smaller species within the Brachypelma genus. The leg span is usually measured from one leg to the opposite leg when fully stretched.
Body Length: The body length of a Brachypelma smithi (excluding the legs) is typically around 2.5 to 3 inches (6 to 7.5 cm). This measurement refers to the length of the cephalothorax (the combined head and thorax) and abdomen of the tarantula.
Size at Maturity: Female Brachypelma smithi can reach full maturity around 4 to 5 years of age, while males mature a bit faster, typically within 2 to 3 years. Females are generally larger than males, a common trait in many tarantula species.
Physical Size of Brachypelma hamorii
The Brachypelma hamorii, often called the Mexican Fire-knee Tarantula, is slightly larger than Brachypelma smithi. Adult Brachypelma hamorii tarantulas typically have the following size characteristics:
Leg Span: The leg span of a full-grown Brachypelma hamorii can reach up to 6 to 7 inches (15 to 18 cm), with some individuals even exceeding 7 inches under optimal conditions. This makes them larger than Brachypelma smithi, which usually maxes out at 6 inches.
Body Length: The body length of an adult Brachypelma hamorii is generally between 3 and 4 inches (7.5 to 10 cm). As with Brachypelma smithi, the size of the body (excluding the legs) plays an important role in the overall dimensions of the tarantula.
Size at Maturity: Like Brachypelma smithi, females of Brachypelma hamorii tend to be larger than males. Females can reach their full size in about 4 to 5 years, whereas males reach sexual maturity in approximately 2 to 3 years.
Size Comparison: Brachypelma smithi vs. Brachypelma hamorii
When comparing the sizes of these two tarantulas, it’s clear that Brachypelma hamorii tends to grow larger than Brachypelma smithi. Here’s a breakdown of the key size differences:
Leg Span:
- Brachypelma smithi: 5 to 6 inches (12 to 15 cm)
- Brachypelma hamorii: 6 to 7 inches (15 to 18 cm)
Brachypelma hamorii is generally larger by about 1 inch in leg span.
Body Length:
- Brachypelma smithi: 2.5 to 3 inches (6 to 7.5 cm)
- Brachypelma hamorii: 3 to 4 inches (7.5 to 10 cm)
Again, Brachypelma hamorii has a noticeably larger body size compared to Brachypelma smithi.
Size at Maturity:
- Brachypelma smithi females are around 5 inches (12.5 cm) at full maturity, while males are slightly smaller at around 4 inches (10 cm).
- Brachypelma hamorii females can reach up to 6 inches (15 cm) or more, while males are around 5 inches (12.5 cm) at maturity.
Factors That Influence Size
The size of any tarantula, including Brachypelma smithi and Brachypelma hamorii, can be influenced by several factors, including genetics, diet, and environment. Here’s a closer look at what can affect the size of these two species:
Genetics: Just like any other species, individual tarantulas will vary in size depending on their genetic background. Larger specimens are often more prominent in the wild, but even captive-bred tarantulas can differ in size.
Diet: A healthy and varied diet is essential for the growth of a tarantula. Adequate feeding with insects like crickets, roaches, and worms contributes to better growth. A well-fed Brachypelma hamorii will likely reach the upper end of its size range, while an underfed Brachypelma smithi might remain on the smaller side.
Temperature and Humidity: Tarantulas are sensitive to environmental conditions. Ideal humidity and temperature levels encourage optimal growth. Inconsistent or incorrect humidity and temperature can stunt a tarantula’s growth.
Molting Cycle: Tarantulas grow by shedding their exoskeleton in a process called molting. The frequency and quality of molts play a major role in a tarantula’s overall size. Females generally molt less frequently than males, which contributes to their larger size over time.
Other Physical Characteristics
Apart from size, Brachypelma smithi and Brachypelma hamorii share many similarities in appearance, though some physical traits help differentiate them.
Coloration
Brachypelma smithi is known for its striking black body with orange-red markings on the legs, creating a “red-knee” effect.
Brachypelma hamorii also has red-orange markings on its legs, but its coloration is usually more vibrant and brighter compared to Brachypelma smithi. The “fire-knee” effect is more pronounced in Brachypelma hamorii.
Temperament
Both species are known for being docile and relatively easy to handle, though some Brachypelma smithi can be slightly more skittish than Brachypelma hamorii. However, both are suitable for beginner tarantula keepers.
Conclusion
In summary, while both Brachypelma smithi and Brachypelma hamorii are similar in many ways, Brachypelma hamorii generally grows larger, with leg spans of up to 7 inches (18 cm), compared to Brachypelma smithi, which typically maxes out around 6 inches (15 cm). Factors like diet, genetics, and environmental conditions can influence the size of these tarantulas, but Brachypelma hamorii consistently reaches a larger size. Whether you are looking for a smaller tarantula or a more robust species, understanding the size differences between these two is essential for any potential tarantula owner.
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