Missouri Master Naturalists- Springfield Plateau Chapter

Friday, August 16, 2019

Another Jumping Spider












I saw what initially looked like a small ant slowly scouting the surface of a patio table.  It was less than a quarter inch long (5mm) and skittish when I got too close.  I was able to get these pictures with my cell phone, a bit blurry when blown up but good enough to ID it on INaturalist as a Common Hentz Jumping Spider, Hentzia palmarum.

It has impressive front legs that resemble a crab spider.  When I got too near it jumped several inches over the table edge and dangled by a trailing strand of silk before climbing back up.  Jumping spiders don't build webs but also use their silk to create a burrow to hole up into.

H. palmarum - Large central eyes - "The better to measure the jump on you with"  - Wikipedia
H. palmarum  David Hill - Wikipedia
They hunt by relying on their large eyes in front as they stalk their prey (See last month's blog for a discussion on their binocular vision).  The long front legs holds their prey while they inject their venom.  The black and white striped structures in this photograph are their pedipalps or jaws.  The large pedipalps and dark color generally identify this as a male.  There is a good video of H. palmarum in action at this Youtube link.

Female H. palmarum - Brandon Woo

There is a dramatic difference in appearance between the male and female, making them look like separate species.  According to Bugguide "Females are hairier, paler in color, often marked with forward pointing triangles along the center of her abdomen."

Brandon Woo's specimen looks warm and cuddly compared to the males, unless spiders aren't your thing.