Unknown Aquarium Creature probably Aquatic Pyralid Moth Caterpillar

Insect larvae ? aquatic.
January 16, 2010
This “being” is attached to my aquarium glass wall. It flows with the movement of the water circulation with one end attached to the glass. It looks at first glance like a grub. A teeny grub. It is at most 1/4 inch. The attached end is a dark brown and the far end has a small dark area. The body is a light color and seems (accordion shaped) slightly extend-able like a caterpillar or grub. It is somewhat bristly…to catch food?
Could this be a crane fly larvae? I recently introduced some plants to the aquarium and they may have introduced this animal. It may remain an aquatic being and therefore would not technically be an insect. The water is mostly freshwater with the slightest amount of sea salt.I’m slowly introducing salt to a red claw crab that started life in a pet store’s fresh water tank.
It may not b a bug at all and would not be fall in “What’sThat Bug” jurisdiction.
Fredericksburg Va mostly freshwater aquarium

Unknown Aquarium Creature

addendum to ” Insect larvae aquatic
January 16, 2010
Further notes. BW pics are clearer to read. The unattached area of the “being” seems to periodically expand like a balloon. It is attached with a cord like piece near the bottom of the tank and has no air available.
I’ve become obsessed and am going blind looking through a magnifying glass. I do hope you can give it a name!

Unknown Aquarium Creature

Dear swarner,
We are very intrigued by your creature, though we aren’t certain at this point what it might be.  Creatures that appear in aquaria are a special curiosity for us.  Hopefully, time will provide an identification for this creature.  We strongly recommend that you attach a comment to this posting which will automatically provide a notification if someone else comments down the line.

Karl to the rescue!!!
I am inclined to think that this is the larvae of an aquatic moth, probably a snout moth in the family Pyralidae, which includes most or all lepidoptera with truly aquatic larvae. It is difficult to see much clear detail from either of the photos, but I think I can make out the reduced prolegs with crochets (hooks) in the black and white photo.  Compare this photo to close-ups of the crochets and the terminal abdominal segment of a pyralid larva provided on the ‘Digital Key to Aquatic Insects of North Dakota’ site. The larvae of aquatic Lepidoptera are almost always associated with aquatic plants and can be stem borers, leaf miners or leaf feeders. Regards.

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