So Why Spiders?

Truth-in-blogging-disclaimer: Much of what follows was a response to a question on Quora.com, viz: “Why do you like spiders?” I have been asked this a number of times, and thought that I’d really rather direct people to my admittedly often-ignored-blog than to Quora, so with some minor changes, this is how I answered that question:

First, though, the non-asked question “Why bugs?” is easy: I was born an entomologist. My earliest memories are of collecting insects, and my mother always told me that, as a baby, I would lie in my playpen and watch the ants rather than play with toys. At age 8, when I learned it could be done—and that it would be would be essential for a professional career—I decided to get a Ph.D. in entomology.

I remember, too, at age 4 when we lived in Douglas, Arizona, I would go into the garage and kill the “black widows” therein—and black widows only*👇, as I had been told to leave them alone, their being “bad” spiders and potentially dangerous.

Now, it’s true that spiders aren’t insects, of course, but as it turns out, educationally, entomologists get the arachnids, and plant pathologists get the nematodes. So I had always had a general interest in spiders, flies, and beetles…at least somewhat more than in most other arthropods.

What really got me interested in spiders, though, was one particular observation that I made in the 1970s, while I was in grad school studying entomology. One day, while driving from home to school, I noticed an adult female Phidippus audax (a robust and very common jumping spider) peeking out from the edge of my sun visor while resting upside down on the car’s headliner.

<i>Phiddipus audax</i>
Phiddipus audax, the bold jumper

Now, as might be imagined, jumping spiders stalk their prey and, when close enough, um… jump on it. This particular spider was stalking a fly, also upside down and resting on the headliner about 4 inches from the sun visor. The spider crept out stealthily closer to the fly, and then suddenly leapt at the fly. The fly, of course, flipped and took off.

The spider intercepted the fly’s trajectory, grabbed it in mid-flight, and, thanks to its ever-present drag line, swung down with the fly, climbed back up the drag line, and carried its prey back behind the sun visor for a leisurely lunch.

I was thinking: no big deal, right? Spiders do this all the time.

But then it dawned on me that the spider and its prey had been upside down. Thus, it’s impossible for a spider to jump from one spot on a headliner to another, because as soon as it jumps, it begins to fall, i.e., gravity makes it impossible for the spider to jump onto the fly, instead, the spider’s downward trajectory had to intercept the fly’s!

Now, how did the spider know this? Do upside down jumping spiders “know” they’re upside down? Do they “know” their prey will have a downward trajectory, too?

And so I wondered: How on earth did that spider ever catch that fly? Luck?

That one incident led me to focus on spider biology and behavior. Spiders never became my job. I did teach Araneology at Cornell, but that was not the main focus of my job there. Instead, it was something I undertook owing to my passionate interest, an interest that has never waned.

And, speaking of gravity…


* Probably the western black widow, Latrodectus hesperus, but my parents called them simply “black widows.” *👆

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