Wednesday, August 19, 2009

Dome spiders mating, Discovery Park

At this time in summer, spiders and their webs get larger and more conspicuous. In Discovery Park, the most often seen types are orb webs, and dome webs.

Here's a dome web.

And here are some more. In most of the webs, a single spider sits upside-down in the middle.

But some had two spiders, who were busy making more spiders. Here's how spider making works: the male (on the right in this picture) carries sperm on his palps - a pair of appendages in front of his fangs. (The male in this pair had red palps, as if he was holding a pair of boxing gloves.) The palps fit into the epigyne, a plate under the female's abdomen.

Both palps and epigyne are shaped so that only males and females of the same species can link up.

Here you can see the male's palps. I thought they looked like tiny boxing gloves. A couple of times, they unhooked, and quickly backed off each other. Then the male would move toward the female, plucking at the web as he came forward, and they'd clasp again.

This web had three. The male is at the bottom. A female is just above him and a second female is in the upper strands. How did that happen?

1 comment:

Anonymous said...

Wow, fantastic photos, Fiona! I had no idea how they mated - though I see dome spiders all over Lincoln Park and have tried to get effective pictures of them. Thanks!