Wednesday, October 28, 2009


Hallowe'en this week, and for whatever reason spider science has been making headlines.

For instance, there's a new giant orb-weaver spider from Africa. Orb-weaver spiders are that archetypical spider that most of us think of when we think spiders. They're the ones we see sitting on the webs, that capture insects as they fly by, and are the type we put up as part of our Hallowe'en displays. We have plenty of orb-weaver species here in Canada, but this African one is in a league of its own. First of all, there's the size: the females of this particular species (Nephila komaci) grow to about 10-12 cm across, while the males are 1/5 that size. Can't picture that? It's about the size of the palm of a large man's hand! Then there's the web. Unlike most diaphanous spider webs, this one, over a metre across, is more string like, and is capable of catching small birds. Which the spiders will eat, although they prefer grasshoppers and other insects.

Another spider in the news is the Australian redback. In this case, it's a story of how lazy male spiders can win the mating game. This work comes from the lab of Dr. Maydianne Andrade at the University of Toronto, Scarborough, where they've been studying the mating habits of this relative of the black widow. The interaction of males and females in this species is unique to say the least, it'll be covered in some detail in my book when it comes out in the spring, but for now all you need to know is that the males have to court the females if they want to mate. And it's no short commitment, males have to put in almost 2 hours of attention if they want to mate before they get turned into a meal. Except for this new research, which shows that sometimes males can sneak in and mate without putting in the work, as long as another male has spent the time in courting. The bad news, for the hard worker, is that he doesn't get to mate, he's out-maneuvered by the other male.

And talking of sneaky spiders, earlier this year a spider was discovered making a decoy. By taking refuse and packing it together on the web, it can make a copy of itself to distract predators.

Why so much spider science? Part of it is probably just pure curiosity. But spiders are interesting for another scientific reason. They're a great model for studying evolution and behaviour. Take the male/female size difference. By looking at closely related spiders, we can understand what's driving this evolution in size disparity. The same with behaviour; spiders are a great system for looking at sexual conflict between males and females, and again, sometimes closely related species can behave quite differently, which lets researchers ask interesting questions.

If only they were a little cuter...

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