Saturday, 18 January 2014

Tummy ache

My proposal is kind of on ice until I get the last comments back from my supervisor. While that freaks me out a bit, it has given me a chance to start getting to know Cantuaria more personally. Naturally, that requires me to dissect out their genitalia and photograph it.

Female spider genitalia is found around the top of the belly - more specifically, the anterior end of the ventral side of the abdomen. The genitalia is useful in identifying what species the spider is. I use a hypodermic needle to slice around the girly bits, then lift it off with some tweezers. At this point I am really happy that my spiders are huge, rather than tiny little things that I would end up impaling. You then put the genitalia into some clearing agent (potassium hydroxide, which is also used to make liquid soap) and incubate it at body temperature for a few hours. My advisor recommended putting it in a water-tight tube and in my pocket, but after discovering my tubes weren't water-tight and getting a very sore pocket area as a result, I found storing them inside my bra worked pretty well at keeping them warm and upright. Of course, it makes one's chest look a bit odd and lumpy. One of my friends asked me why my boob looked so odd and I told them that I had genitalia in there. They told me that is okay and they accept me for who I am. I don't get it.

Upon lifting the genitalia from the abdomen of one female, I found an odd convoluted object as opposed to the normal white meat you get underneath. I sliced down the middle of the abdomen to investigate.
The convoluted thing seemed to fill the whole abdomen. I separated the abdomen from the cephalothorax (the front half of a spider) to have a better look, cut two flaps either side of my incision and prized them apart with tweezers.

Behold! A worm!

These nematode worms are known to infect Cantuaria from time to time. They go for the adult females and change their behaviour, forcing the ordinarily agoraphobic females to leave their burrows and seek water. Once in the water, the worm emerges from the spider and breeds. The worm eggs are laid in aquatic larvae (infective stages have been found in caddifly larvae, for example), which pupate into adults and are then eaten by a spider, and the whole cycle proceeds in all its bizarre and sadistic glory.

Next time you are marvelling at the wonder of nature, at the stunning colours of a hummingbird or the amazing engineering of spider silk, consider the spider in the photographs above. Nature is wonderful and fascinating, but dark and scary as hell. No merciful god created this.


  1. The nematode eggs are thought to be ingested by freshwater insect larvae (e.g. caddisflies and mayflies), there they develop into infective pre-parasitic juvenile mermithids and remain in the adult insects, which are then eaten by spiders.

  2. Thanks for the clarification, I'm not sure why I thought it was crustaceans.