Mexican Orangeknee Tarantula

Appearance

"Brachypelma hamorii" is a large spider. A sample of seven females had a total body length in the range 52–54 mm. A sample of 11 males was slightly smaller, with a total body length in the range 46–52 mm. Although males have slightly shorter bodies, they have longer legs. The fourth leg is the longest, measuring 75 mm in the type male and 67 mm in a female. The legs and palps are black to reddish black with three distinctly colored rings, deep orange on the part of the patellae closest to the body with pale orange–yellow further away, pale orange–yellow on the lower part of the tibiae, and yellowish-white at the end of the metatarsi. Adult males have light greyish-red around the border of the carapace with a darker reddish-black marking from the middle of the carapace to the front of the head; the upper surface of the abdomen is black. Adult females vary more in carapace color and pattern. The carapace may be mainly black with a brownish-pink border, or the dark area may be broken up into a "starburst" pattern with pale orange–yellow elsewhere.

Distribution

"B. hamorii" and the very similar "B. smithi" are found along the Pacific Coast of Mexico on opposite sides of the Balsas River basin as it opens onto the Pacific. "B. hamorii" is found to the north, in the states of Colima, Jalisco, and Michoacán. The natural habitat of the species is in hilly deciduous tropical forests. It constructs or extends burrows under logs, rocks, and tree roots, among thorny shrubs and tall grass.

Their burrows were described in 1999 by a source that did not distinguish between "B. hamorii" and "B. smithi". The deep burrows keep them protected from predators, such as the white-nosed coati, and enable them to ambush passing prey. The females spend the majority of their lives in their burrows, which are typically located in, or not far from, vegetation, and consist of a single entrance with a tunnel leading to one or two chambers. The entrance is just slightly larger than the body size of the spider. The tunnel, usually about three times the tarantula's leg span in length, leads to a chamber that is large enough for the spider to safely molt. Further down the burrow, via a shorter tunnel, a larger chamber is located where the spider rests and eats its prey. When the tarantula needs privacy, e.g. when molting or laying eggs, the entrance is sealed with silk, sometimes supplemented with soil and leaves.

Behavior

Like all tarantulas, "B. hamorii" is an arthropod, and must go through a molting process to grow. Molting serves several purposes, such as renewing the tarantula's outer cover and replacing missing appendages. As tarantulas grow, they regularly molt, on multiple occasions during the year, depending on the tarantula's age. Since the exoskeleton cannot stretch, it must be replaced by a new one from beneath for the tarantula to grow. A tarantula may also regenerate lost appendages gradually, with each succeeding molt. Prior to molting, the spider becomes sluggish and stops eating to conserve as much energy as possible. Its abdomen darkens; this is the new exoskeleton beneath. Normally, the spider turns on its back to molt and stays in that position for several hours, as it pushes fluids just beneath its old exoskeleton and wiggles its limbs to loosen off the old and reveal the new exoskeleton. Once this has been accomplished, the tarantula does not eat for several days to weeks, and not uncommonly for up to a month after a molt, as its fangs are still soft; the fangs are also part of the exoskeleton and are shed with the rest of the skin. The whole process can take several hours and sheaths the tarantula with a moist, new skin in place of an old, faded one.Like most New World tarantulas, they kick urticating hairs from their abdomens and their back legs if disturbed, rather than bite. They are only slightly venomous to humans and are considered extremely docile, though, as with all tarantulas, their large fangs can cause very painful puncture wounds, which can lead to secondary bacterial infection if not properly treated and allergies may intensify with any bite.