Today is our last day of counting nematodes! We are finishing up the last samples now.
I previously talked about how we sample and how we extract the nematodes, rotifers, tardigrades, and other small animals from a soil sample.
The next step is to examine the sample under a microscope. I explained the physical process of counting in my post about the lab, especially in the long caption under the picture of our microscopes. We scroll through the sample in a special sample counting dish and use a counting machine to keep track of things. We identify all of the nematodes by species, sex or stage in life cycle (male, female, or juvenile. Juvenile nematodes from the species we see don't have visible sex organs so we count all of them as juvenile), and living or dead. For tardigrades, rotifers, and everything else, we just identify them generally (tardigrade, rotifer, or "other" which usually means protozoan) and we only count the living specimens.
A female Scottnema lindsayae. You can see the indentation of the vulva pretty clearly
A juvenile Scottnema lindsayae. No reproductive structures are seen.
Main body of a Plectus murrayi juvenile. No reproductive structures are seen.
Same Plectus as above except you can clearly see the distinctive tail characteristic of a Plectus
Five nematodes, all Scottnema lindsayae. The one on the top and the second on from the left are male. The one on the bottom right is a female, and the other two (the one in the middle on the right and the one farthest left) are juveniles. For the males, you can see the spicules as an angled structure in the tip of their tail.
A male (you can't tell that it's a male from this picture) Eudorylaimus antarcticus. Adults like this guy are so huge! It is impossible to fit the whole thing in one picture and have it be in focus!
My video of an Antarctic tardigrade
My video of a collection of Scottnema lindsayae
So that's the stuff that we normally see! We see tons of Scottnema in the dry soils. When we sample closer to the streams or lakes, the diversity increases and we start to see a variety of these other animals too (and the numbers of Scottnema either drop low or disappear). In a plentiful sample, we can see 1000 nematodes. In a normal sample, we'll see a couple hundred. A few samples have absolutely nothing! It is still amazing to me that we find so many microscopic animals in such a desolate location. When we're sampling, it looks so dry and inhospitable that I can't imagine life to exist there.
