Another male: Red phase Chilean rose tarantula (Grammostola rosea)

Red phase Chilean rose (Grammostola rosea) and shed exoskeletons from molts on October 4, 2012 (left) and November 28, 2012 (center). Click/double click to enlarge.

The red phase Chilean rose (Grammostola rosea) molted much earlier than anticipated. The molt was completely normal, taking place during my field biology class and two of my four Introductory Biology classes (approximately four hours). Perfect timing!

I hoped to confirm gender immediately after this molt, comparing images of the new exoskeleton to the exoskeleton from the previous molt (see previous entry). I was disappointed to see that the potential early developing spermthecae shown in the previous entry appear not to have been spermathecae after all. This individual appears to be male. Though more vibrant in adult coloration, male red phase Chilean roses have a much shorter lifespan than the females.

Leg markings have now appeared. If you double-click the picture above, you’ll see striped markings on the legs.

On the positive side, this spider should be my first male to mature, so the kids and I’ll get the opportunity to see sperm web development as well as observe male structures and behavior.

Still kind of disappointed….

Notice the lack of distinct spermathecae directly above the gonopore. Click/double click image to enlarge.

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Red phase Chilean rose (Grammostola rosea) juvenile gender determination

This red phase Chilean rose tarantula  (Grammostola rosea) juvenile appears to be female. Click image to enlarge.

I rehydrated the exoskeleton of this young red phase Chilean rose tarantula (Grammostola rosea) to determine whether gender could be established at this point. This year old individual is still relatively small (diagonal leg measurement of 1 3/4″).

Though too small for definitive determination, it appears that the structures directly below the label are likely immature spermathecae. Thanks to Jen Newman (Heartland Invertebrates) for confirming the likelihood.

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Rehydrating an old pink toe tarantula (Avicularia avicularia) exoskeleton for gender determination

Female pink toe tarantula (Avicularia avicularia). Note the single horned spermatheca above the gonopore. I assume I damaged the other horn of the spermatheca during the rehydration/abdomen separation process. Click/double click image to enlarge.

I’ve been awaiting the molts of my two $5 Craigslist pink toe (Avicularia avicularia) tarantulas. Since I’m feeling more confident regarding gender determination using fresh exuvia, I decided to try doing so using an older exuvium.

I soaked an exoskeleton from its previous molt (12 weeks ago) for several minutes and then photographed it.

Not surprisingly, I did a little bit of damage opening it up, but the tarantula is clearly a young female. Still awaiting the molt of the other, stockier, heavier-bodied pink toe.

Thanks to Jen Newman (Heartland Invertebrates) and Paul Lawniczak for confirming gender of this individual.

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Rehydrating an old curly hair tarantula (Brachypelma albopilosum) exoskeleton for gender determination

Unfortunately it’s a male. Note the small red, bulbous accessory structures above the label. Click/double click image to enlarge.

I’ve been awaiting the molt of my larger Honduran curly hair tarantula (Brachypelma albopilosum) in hope of being able to verify its gender. Since I’m feeling pretty good about determining gender using fresh exuviae, I thought I would try doing so using a older, very dry exuvium.

I soaked the exoskeleton from the tarantula’s previous molt (10 weeks ago) in warm soapy water for several minutes and then photographed the exoskeleton. Note to self – just use one drop of dish detergent next time. The best image is shown above. I initially (optimistically?) thought this individual to be a female with small spermathecae, but correspondence with Jen Newman (Heartland Invertebrates) made clear to me that it is much more likely that this individual is a male. The structures I initially thought to be spermathecae are more likely male accessory organs.

Exact function of the accessory organs is unknown, though it is thought that they produce an adhesive liquid that helps the sperm droplet stick to the sperm web, used to transfer sperm from the gonopore to the pedipalps. Accessory organs can be very prominent in some species, including members of the genus Brachypelma.

I’m pretty disappointed in the result. Lifespans of males are so much shorter than those of females. Males curly hairs often live six months to a year after their final molt, which may be the one I’ve been awaiting. This individual, purchased as  juvenile less than a year ago, has been the easiest and calmest handling tarantula of the bunch. I’ll miss him.

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Honduran curlyhair tarantula (Brachypelma albopilosum) leg regeneration

Honduran curlyhair (Brachypelma albopilosum) exoskeleton (November 5, 2012 molt) and newly emerged spider (photographed November 6, 2012). Double-click image for best visual leg comparison.

The smaller Honduran curlyhair tarantula (Brachypelma albopilosum) emerged from its previous molt (September 14, 2012) with an issue. Upon close inspection it was clear that the hindmost right leg did not successfully emerge from the previous exoskeleton, effectively confining it within a small sheath that prevented it from increasing to normal size.

The spider was pictured at that time in “Honduran curlyhair tarantula (Brachypelma albopilosum) molting issues.”

At the time I questioned whether the spider would shed its confined, smaller leg or retain that leg. Now I know the answer!

The spider did in fact retain the confined, well encased smaller leg throughout the intermolt period. Amazingly, the new leg developed FULLY inside its tiny sheath, though it did take several hours longer than the rest of the legs to expand to its present, normal state.

The newly enlarged, normally functioning right hind leg is pictured below.

Newly regenerated right hind leg. It is fully functional and identical in movement and appearance to the other hind leg. Click image to enlarge.

As a side note, the spider’s exoskeleton-based gender determination (it’s a girl!) is discussed and shown in the previous entry, entitled “Honduran curlyhair tarantula (Brachypelma albopilosum) gender determination.”

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Honduran curly hair tarantula (Brachypelma albopilosum) gender determination

Gonopore and two clearly outlined reddish spermathecae, indicating this individual is an immature female. Click image to enlarge.

I came in to school this morning to see the smaller Honduran curly hair tarantula (Brachypelma albopilosum) still on its back after a quite successful molt. As it turned upright, I grabbed the shed exoskeleton, immediately placed it on a piece of glass, and spent a half hour teasing open the shed abdomen to reveal the internal abdominal structures.
I wouldn’t have tried to determine gender on a spider this small, but felt confident that if I followed the procedures outlined in a YouTube video entitled “Sexing a Tarantula Tutorial 2,” I might be able to establish gender.

Lacking the clearly darkened spermathecal edges of the individual in the previous entry, this individual is still clearly sexually immature. No surprise there. Life span of females approaches fifteen years, while males life spans tend to be around three years.

Tomorrow I will examine and photograph the spider. I’m looking forward to determining the degree of leg regeneration that occurred in this individual. Its right hindmost leg did not eclose from its exoskeleton during its previous molt (see “Honduran curlyhair tarantula (Brachypelma albopilosum) molting issues“) on September 14, 2012. It retained the miniature, previous exoskeleton-shrouded leg since that time. That regeneration will be the focus of my next blog entry.

Thanks to Joe Mastous and Jen Newman for gender verification!

Exoskeleton of the smaller Honduran curly hair tarantula (Brachypelma albopilosum)  about a half hour after molting. Teasing apart the delicate structures to open up the abdomen was a challenge, but it worked! Diagonal leg measurement of this individual is 2 1/2″. Note the miniature right hindmost leg. Click image to enlarge.

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