Note

Jumping Spider Palpi *

Wayne Maddison

Go to jumping spider anatomy page

Male spiders have an unusual way to get sperm into the females: they use their palpi, the little 'feelers' beside the face. This photo shows where the palpi are (see the arrow).

Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window

In the females, these palpi are simple and leg-like. Both males and females use them like little hands, to manipulate food and to clean their faces.

But adult males have the palpi swollen and more complex (that's one way to tell a male spider: adult and subadult males have the palpi swollen like boxing gloves). If you look at the tip of male palpus, from the underside, you see a complex organ that looks like this:

Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window

Before I explain how it works, let's see more of its structure. Here is a closeup of the palpus, seen under a scanning electron microscope.

Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window

The undersurface has various hard bits and pieces put together in a species-specific sculpture. If you look inside the palp by making it crystal-clear, you see all the following details.

Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window

The important thing to notice is the opening and the sperm duct. When the male is ready, he spins a small web and deposits a drop of sperm on it from the underside of his abdomen. He then places the tip of the palp into the sperm, and draws the sperm through the palp's opening into the sperm duct of the palp. There it is stored.

The male then goes out in search of females. If he finds one, he performs a courtship dance. If she accepts him, he places his palp against an opening on the underside of her abdomen (her epigynum). He locks it in place by putting a thumb-like projection, the tibial apophysis, into a groove that is usually at the back of her epigynum. The palpus then expands. This happens because the various hard bits of the palp are connected to one another by expandable balloons. When they expand by increasing blood pressure, the hard bits move into position to inject the sperm into the female. Here is an image of an expanded palp:

Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window

The codes "bH" and "eH" refer to two of the expandable balloons. "eb" is the tip of the palpus, the part that injects the sperm into the female.
* Included on this page are images from Maddison, W.P. 1996. Pelegrina Franganillo and other jumping spiders formerly placed in the genus Metaphidippus (Araneae: Salticidae). Bulletin of the Museum of Comparative Zoology. l54(4): 215-368. These images are copyright © 1996 The President and Fellows of Harvard College.

Jumping spider anatomy pages:

[Anatomy] [External] [Muscles] [Gut] [Vision] [Palpi] [Epigyna] [Gallery]

About This Page

Wayne Maddison
University of British Columbia, Vancouver, British Columbia, Canada

All Rights Reserved.

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