A different sort of beauty .....

[Triffid]

Loving Junebugs picture!

Yes, how do you sex spiders?
I was led to believe that most females have larger rounder abdomens for their species. Surprised that you can sex them from the head.

Must learn more!

[Junebug]

Originally Posted by Triffid

Loving Junebugs picture!

Yes, how do you sex spiders?
I was led to believe that most females have larger rounder abdomens for their species. Surprised that you can sex them from the head.

Must learn more!

Thanks. I deducted this was a female because of all the babies. The photo was taken a few years back when I was cleaning my slider doors. The family of spiders had established their home in the metal track above the doors. I thought at the time they were some type of widow, but was never really sure. I commonly see brown widows and on occassion a black one, but this one looked different.

[Paul]

Originally Posted by Tindomul

Paul, I'm impressed with your spidey skillz. How do you tell that it is a female?

Originally Posted by Triffid

Yes, how do you sex spiders?
I was led to believe that most females have larger rounder abdomens for their species. Surprised that you can sex them from the head.

Cesar, I must admit that I am making a couple of assumptions here. Based on the time of year in conjunction with how large and plump as the jumper you showed appears to be, I'm assuming it is a mature adult. If it is a mature adult then I definitely know it is a female. If it is still an immature individual, then I have a 50/50 chance of being correct.

Triffid, while it is generally the case that in a mature male will have a smaller abdomen it is not necessarily written in stone (or in this case silk). Particularly with immature spiders, there often is no visual difference at all between the two sexes. (Although in some species the difference between male and female is so extreme, it is hard to believe they are even the same species.)

But on to the question at hand ... how can one sex a mature spider by looking at the spider's head?
It all comes down to looking at the spider's pedipalps. In arachnids pedipalps are a pair of segmented appendages located at the front of the animals head. In spiders they are small leg-like structures found one on either side of the fangs. Spiders ordinarily use their pedipalps to manipulate food and other objects as well as additional sensory apparatus. In mature male spiders, the pedipalps undergo a transformation during their molt to adulthood causing them to take on an enlarged 'boxing glove' like appearance. (This is easily visible on my male red widow.) These modified pedipalps will be used to deposit the male's sperm into the female's genital opening. Here is a pretty decent, simple explanation for those interested: HowStuffWorks "Spider Reproduction"