Friday, July 14, 2006

Recent spider photos

I haven't posted any spider pictures lately, so here are a few in one go. As always, just click on the photo to enlarge it.

I was lucky enough to snap this shot yesterday when I was out on the Dr. George trail in the Sanctuary. It's a female Goldenrod Spider (Misumena vatia) defending her egg sac. These spiders are ambush predators and don't use webs for catching insects, but they do use silk to wrap up the leaf they've chosen to cache their eggs in. This crab spider will spend the rest of her life defending her egg sac; in fact, she's likely to die of starvation (or exhaustion) before the spiderlings hatch out.

Earlier this week I had a chance to watch this spider at work beside my father's fish pond. It's a Long-Jawed Orb Weaver (Tetragnatha sp.). The Long-Jawed Orb Weaver builds a typical-looking orb web, but it's often on a bit of a tilt and has the middle hub removed so that the spider can cross from side to side. Long-Jawed Orb Weavers can be found near wetlands (amongst other places), and will stretch out their long, skinny bodies to camouflage themselves in the reeds. This one didn't have any reeds nearby to hide in, but the cotoneaster leaves in the background should give you an idea of its size.

Since I was planning to post the first two spiders, I thought I may as well include a photo I took last week too. It looks a bit less than natural compared to the other two, but that's just because I sneaked a piece of paper behind the spider so that its markings would show up better. It's called a Bowl-and-Doily Spider (Frontinella communis) and is a member of the Linyphiidae or Sheet Weaver family. The web this spider builds is quite remarkable. The top part looks like an upside-down bowl, and it's suspended above a flat-sheet "doily". The web isn't sticky, but is enough to hinder any small insects that fall on it long enough for the spider to bite through the web and drag its prey under. The Bowl-and-Doily Spider's markings often look a bit like a cursive "mc".

Each of these spiders is harmless to humans, as are the vast majority of spiders here in Alberta.

We don't have a resident spider expert at the Nature Centre, but if you have spider (or other) questions please don't hesitate to give us a call. We'll do our best to see what information we can find for you.

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