Greetings fellow Kossacks! The New Year also ushers in the return of an old friend: Spider Friday. I have a bunch of spiders "on tap" for the subsequent weeks--it's just a question of writing the diaries. In addition, I'm planning on doing editions on paleozoic spiders, including "primitive" spiders still in existence in the modern world.
But for today's edition, since I didn't really have time to write very much, I figured I'd do a brief entry on what we commonly call the Daddy Long Legs--also called cobweb spiders or cellar spiders, or a wide variety of other names.
I'll also clear up some of the confusion about the Daddy Long Legs, including whether or not they really are spiders, and whether it really is true that their venom is lethal but they just don't have the capability of biting humans.
Here we go!
Kingdom: Animalia (Animals)
Phylum: Arthropoda (Arthropods)
Class: Arachnida (Arachnids)
Order: Araneae (Spiders)
Suborder: Araneomorphae (true spiders)
Family: Pholcidae
Owing to their family name, as you can see above, Daddy-long-legs spiders are more technically known as pholcids. You've all seen them, I imagine--their distribution is worldwide. And they come, of course, in way too many genera and species for me to list here (959 currently described species, in fact). Some have globular abdomens, while some have more cylindrical abdomens. And that's really the only major difference--they all kind of act the same :-) Here's a nice picture of our most common pholcid, P. phalangioides, from the Wikipedia Commons.
They're called cellar spiders for an obvious reason--because you usually find them in garages, cellars, or other dark, dank places in your home. These guys are what you have to clean your garage for.
But cellar spiders also have a different, though less colloquially used, common name: vibrating spiders! And there's a very good reason, and maybe you've seen it yourself when, well, cleaning out your garage and you accidentally or intentionally disturbed a pholcid: if they don't just run away, they'll start vibrating rapidly using their really long legs! Originally, back when I would disturb pholcid webs as a kid, I really thought it was coincidental sudden gusts of wind that were making the spiders do what they did, but now I know better. Wanna see a vibrating pholcid? Here you go!
Now, to most people, a garage full of pholcid spiders signifies a dirty garage that needs to be swept. To me, it signals a safe, healthy garage. That's because pholcid spiders are more than happy to catch whatever prey flies into their web, but if food gets scarce, many species will actively hunt other spider species, including widows and hobo spiders, by leaving their webs to go vibrate the webs of the other spiders! Pholic spiders have been observed preying on redbacks, hobo spiders, and other common household arachnid pests. Kind of puts this photo I took a little while back in a new light!
Sometimes pholcids will even resort to cannibalizing their own species if food is scarce. A spider has to do what a spider has to do.
As with most spiders, I always say that all you have to do is look into their eyes to recognize them. All 8 of them, in the case of the pholcids. Not that you'd have a hard time distinguishing a pholcid from other spiders anyway, but pholcids have an eye structure with two lateral clusters of three eyes each, and a medial cluster of two eyes (i.e., three eyes on each side and two in the middle), as P. phalangioides is more than happy to demonstrate for us:
LIFECYCLE:
Really, it varies. You'll find pholcids year-round, provided things don't get too cold. And even if they do, you'll more than likely find them around the house! The females don't generally produce very many eggs--generally a couple of dozen thinly wrapped in silk. Unlike a lot of spider egg sacs that are really more like egg cases, with many pholcids you can clearly see each egg:
Spiderlings hatch, and then balloon away. There's really nothing absolutely fascinating about a pholcid's lifecycle. I wish I had something interesting to say. But the egg sacs are pretty cool.
MYTHOLOGY:
Ever heard that cellar spiders have lethal venom, but don't have the power to penetrate human skin? Well, that's not based on anything scientific. It's a rumor. First of all, there have been no reported cases of pholcid envenomation in humans. Second, the jaw structure is actually theoretically long and powerful enough to penetrate human skin--the jaw structure and envenomation methodology is similar to that of a brown recluse, though perhaps not as strong.
But most importantly, no toxicology study has been conducted regarding the effects of pholcid venom on a mammalian system (from Rick Vetter, entomologist at UC-Riverside). I have read in some other sources, however, that toxicology studies on insects have shown that pholcid venom is actually relatively weak on insects.
OTHER MYTH:
You've probably also heard that daddy-long-legs aren't real spiders. But that's only because of what the colloquial term "daddy long legs" refers to. Pholcids are most definitely spiders, but the colloquial term can also refer to a group of arachnids called Harvestmen (technically, Opiliones, which, while closely related to spiders, are not true spiders. Harvestmen are arachnids with a what appears to be a single fused body segment, as opposed to a clearly distinct cephalothorax and an abdomen, like spiders have. Furthermore, harvestmen, as their name implies, do not build webs at all--rather, they are omnivorous, feeding on rotting material as well as the occasional thing they happen to catch if they're lucky. They also have no venom, and are completely harmless.
(Harvestman--kind of looks like a spider, but isn't)
I invite you to browse Wikipedia for all the Harvestman you can handle :-)
That concludes Spider Friday! Not my best entry--I'll try to outdo myself next week if I get the chance.