Sunday, November 21, 2010

More Tardigrades

On my way to work today (Yes, I go to work on Sundays. Thus are the requirements of lab work.) I pulled up a few square centimeters of moss from a crack in the parking lot. I put it in a petri dish, sprayed some water over it and plunked it on the microscope to see what was floating around. So much! The sinusoidal thrashing of nematodes is unmistakable, and immediately jumped out at me. Several kinds of ciliates wobbled and spun through the water. I have spent far too much time looking at rotifers, so I quickly registered three kinds; two of these swam and third crawled. The crawler would move to a spot on the base of the dish, anchor its back, then do an excellent imitation of a vacuum cleaner, extend and contracting itself in each direction to pass its cilia over the whole surface of a small circle. There was something I think was a tiny annelid, maybe some kind of earthworm. There were tardigrades, so many tardigrades. I was able to get better pictures this time, as there were so many to choose from, it wasn't hard to find them in photogenic poses. I found myself wondering if every scrap of moss around here has so many tardigrades, and if so how many trillions there must be per square kilometer.
Anyway, here, by popular demand, are a couple more pictures.

Note the long curved claws at the ends of the toes, much like a bear has.


A said...

Have you read Microbe Hunters? Anyway you're starting to remind me of Antony van Leeuwenhoek and all the things he examined!

Karen said...

Can you explain the bumpy-looking surface? Also is that a brown spot on the back of each? Mom-K

Dan Levitis said...

The dark spot in the middle of each is its stomach contents. If they don't get any food for a while, that goes away. Imagine what Tardigrades must look like after Thanksgiving!

The surface looks bumpy because they are segmented (sort of like a earthworm) and have a hydrostatic skeleton (like a water balloon). They have a distinct resemblance to the Michelin Man, as both are segmented and keep their shape through internal fluid pressure.

jte said...

The hydras won't eat tardigrades? How big are each of these things relative to each other: hydra, rotifers, tardigrades, nematodes?

Dan Levitis said...

The hydra are a few millimeters long. The rotifers and tardigrades are each up to about 0.2 mm long. Nematodes come in all sizes from a small fraction of a millimeter to over 7000mm (23 feet). The ones I found ranged from 0.1mm up to 3mm.