[jbotz]

From the livescience article linked by another poster: biofilm produced by sulfur-eating bacteria, which in turn metabolize sulfur from the sulfur-rich stream in the cave.

So the whole food-chain here is: sulfur -> bacteria -> midges -> spiders.

[ginko]

Seems like a great place for spider-eating frogs to move into.

[oersted]

> The environment, too, is unusually protected. The cave is hard to reach and is filled with foul-smelling hydrogen sulfide gas, in concentrations too great for most animals to live there.

[IAmBroom]

I don't know why she swallowed a\ f\l\y\ rotten eggs.