Which can be simpler and smaller: Rotifer or Tardigrade?

[Genecks]

I've been reading about small animals with nervous systems. I've read that tardigrades can be microscopic while rotifers are close to microscopic. Surely, I need some say in a scale, but I don't have one. Nonetheless, I've been attempting to figure out which organism can be the most miniscule and yet possess a simple nervous system for somatic interaction with its environment.

 

Which can be simpler and smaller: Rotifer or Tardigrade?

Edited January 9, 2011 by Genecks

[jake.com]

I've been reading about small animals with nervous systems. I've read that tardigrades can be microscopic while rotifers are close to microscopic. Surely, I need some say in a scale, but I don't have one. Nonetheless, I've been attempting to figure out which organism can be the most miniscule and yet possess a simple nervous system for somatic interaction with its environment.

 

Which can be simpler and smaller: Rotifer or Tardigrade?

I assume you can tell the difference between the two, so i'll just post the picture. From what i can tell, there are close to the same size, but it looks like the rotifers are consistently smaller. Tardigrades win in the cool contest, though. At least in my opinion.

[Blahah]

Rotifers:

Most rotifers are around 0.1–0.5 mm long (although their size can range from 50 μm to over 2 millimeters)

 

Tardigrades:

The biggest adults may reach a body length of 1.5 millimetres (0.059 in)' date=' the smallest below 0.1 mm. Freshly hatched larvae may be smaller than 0.05 mm.

- quoted from Wikipedia

 

The groups have a similar range of sizes, with rotifers generally being smaller, at least the ones I've seen. Individual species might be much smaller than that range though. The nervous systems are similarly simple too. Both groups are well studied as models, so if you search the literature you will be able to find plenty of detail.

 

p.s. If you haven't seen tardigrades under a microscope, you should. They are the most interesting thing I've ever looked at through a lens. You can find them on any moss, just put a piece on a slide with a drop of water.

Edited February 17, 2011 by Blahah

[Moontanman]

Tardigrades are certainly tougher than rotifers as adults anyway.