Unknown ciliate 2.

[jason]

Rotifer? Gastrotrich? From Mississippi river water taken from the bottom near the shore, in Minnesota. Magnification at 20x by 10x, and zoomed in a bit with a cellphone camera. Some coleps come zooming through near the end for helpful scale.

I asked his neighbor the amoeba who this is, but he wouldn't say.

[gastrotrichman]

Rotifer. Definitely not a gastrotrich.

[jason]

Rotifer. Definitely not a gastrotrich.

But how can you be so sure???

*checks username*

Okay, then. Carry on.





(And thanks!)

[gastrotrichman]

Sorry for the short response. Gastrotrichs tend to be in more or less continuous, fluid motion using bands of ventral cilia. Many rotifers swim, but use their anterior cilia for that purpose, and lack the longitudinal bands of locomotor cilia that gastrotrichs have. Many (but not all) gastrotrichs are covered with scales. The "searching" behavior of your rotifer is not typical of gastrotrichs. Most freshwater gastrotrichs are more or less bowling pin shaped. In short, the shape, lack of scales, lack of ventral bands of cilia, and behavior of your rotifer all indicate that it is not a gastrotrich. That said, it is worth noting that a few rotifers are difficult to distinguish from gastrotrichs at a glance … I've been fooled a few times while scanning with a stereo scope with low magnification. Incidentally, you can immobilize most freshwater gastrotrichs by using 1-2 percent magnesium chloride (7 percent for marine gastrotrichs) … some products for de-icing sidewalks consist of magnesium chloride if you don't want to buy from a scientific supply house. They also can be immobilized by wicking away water until they are squeezed under the cover slip. If you don't immobilize them, you can spend a lot of time chasing them (although they eventually may stop).

[jason]

All very good information. Thanks, again!