A spider’s nightmare
In the contest for Ickiest Thing, spiders and molds are about neck and neck. Personally, I’m rooting for molds. To demonstrate their clear superiority over spiders, I now present these two tableaux of death, captured in glorious detail by photographer Kent Loeffler.
This first little fungus, a mold called Nomuraea atypicola, is not dangerous to you or I, but as you can see, it is a mortal enemy of spiders. It’s not just growing on the spider, like a bad case of athlete’s foot. No, it has consumed it from the inside, and it is now making a kajillion pinkish spores on the cadaver. Kind of like that old movie, Invasion of the Body Snatchers. This spider is thoroughly dead.
Quicktime 5+ object
Rotatable, zoomable Quicktime object by Kent Loeffler
Here’s another one, related but quite distinct. This is Gibellula pulchra, another spider pathogen. It too kills only spiders, infecting them when fungal spores land on the unfortunate spider. Those spores germinate and directly penetrate through the exoskeleton, then the fungus begins to grow inside the spider. It just grows and grows until it has digested the whole spider. Fungi digest their food by excreting their digestive enzymes right into it, then absorbing the products of digestion–can’t be very nice for the spider. The fungus doesn’t bother to eat the exoskeleton, which is tough and chitinous and hard to digest. That’s why the cadaver is still recognizably a spider.
When all that devouring is done, it’s time to sporulate. Now the fungus erupts from the cadaver and makes the tiny leafy trees you see covering the spider body. The trees (ok, they’re called synnemata) produce vitamin-shaped spores that are presumably carried by the wind to unlucky spiders. Fungi are classified based on how they make their spores. Gibellula species make those tiny trees; Nomuraea species don’t. There are hundreds of mold genera–all make their spores in different ways.
Quicktime 5+ object
Rotatable, zoomable Quicktime object by Kent Loeffler
We don’t know all that much about how these pathogens affect spider ecology. How do they impact spider populations? How often can spiders fight off a fungal infection? How are they transmitted? How many spider species are suceptible? And I can anticipate your inevitable question: How can I use these to kill the spiders in my house? I don’t have answers for you. In the basement of my old house, with no help from me, pholcid spiders often died from fungal infection. They suffered from yet another mold, Engyodontium aranearum, which never managed to kill ALL my spiders, alas.
On days like this I ask myself, how did I get to this strange place? I don’t know, but I love this stuff.
These spiders died under leaves in Florida. Finding them involved sharp eyes and a lot of creeping around and leaf flipping–Mindy Liu did that. The dead spiders now make their home in the Cornell Plant Pathology Herbarium, one of the biggest fungal herbaria in North America. We have all kinds of weird and wonderful fungi, a bunch of plant diseases, and an impressive collection of historic photographs. We’re 99 years old. We’re not open to the public; you’ll have to stay tuned here for more stories.
- Evans, H. C., and R. A. Samson. 1987. Fungal pathogens of spiders. The Mycologist 1:152-159.
Trackback from Bouphonia, a strange an interesting place.
[…] When people talk about fungi it’s usually in the context of a tasty dish, or that fuzzy brown thing on your peach, but rarely ever are fungi referred to as deft, vicious killers. What you say? Killers? Well, fungal pathogens have long preyed on insects, claiming millions of victims yearly and all over the world. An array of pathogenic fungal genera can infect a broad range of insects [and spiders! –Ed.]. Once an insect has been exposed to spores, the developing fungus may induce behavioral responses in its host. These behavioral responses may result in improved spore dispersal and fungal fitness. But behavioral responses may also be defensive, ultimately benefiting the host. One of these responses is behavioral fever, in which insects raise their body temperature as a means of literally toasting a fungal invader. […]
wow cool
From what I understand, there’s actually a different kind of mold for various species of insects in the rain forest. This kind attacks spiders and nothing else. There’s another one for example, that attacks ants. What’s interesting is that it messes with their minds and can make them go crazy. The infected ants are usually kicked out of the colony as it can destroy every single one of them. God help us if there’s ever a strand that can infect humans!
I found a great specimen of a spider covered in delicate mould here in Holland last night. Lots of photos because I’ve never seen such a thing before. Is it of any interest/value to any institution? Nearly 2 inches across it looks like a spider made of a pure white pipe-cleaner by a kid.
Alas, my daughters and I had to go down to the “other” basement due to a tornadoe threat. There were many of these spiders, now, a couple were definitely alive, as they were moving. As an arachniphobe, I was terrified, my children were terrified, and it would have been more comforting to be upstairs with the tornado, than to bunk up with these freaks of nature. Yes, they did look like white pipe cleaners and on every knuckle they had a white ball. I want to cry.