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Nocturnal Aquatic Centipede?

Nocturnal Aquatic Centipede?
Portland, Clackamas County, Oregon, USA
January 24, 2015
Size: 1-1.5 inches
I found this creature during a night walk at about 8:30 PM. It was sitting motionless on the bottom of a creek, but moved when I put my flashlight on it. Could this be an aquatic centipede, if there is such a thing? It looked a little off for an isopod (which we have in a nearby pond). Is a Bathynellacea (I've never seen one of these) a possible option? The habitat around here is like Forest Park in west Portland; 900 foot elevation fir forest with lots of sword fern and oregon grape, and very little ivy or blackberry.

Thanks very much for your help,

Images of this individual: tag all
Nocturnal Aquatic Centipede? Nocturnal Aquatic Centipede?

Moved from ID Request.

Not a centipede :)
Looks like a Corydalid (Dobsonfly or Fishfly) larva:

Hold on to see if others agree.

:)Those lateral fleshy projections are not legs.

Thanks for the identification. It makes a lot more sense than the discovery of the first ever aquatic centipede... What are the lateral fleshy projections? Those have me stumped.

Thanks again,

Every reference I've seen...
...simply calls them "lateral filaments," and none connects them with any specific function (except to note that they are not gills). Perhaps no one knows what, if any, purpose they serve.

One theory...
I was taught that while they are not gills they do aid in oxygenation of the hemolymph. Some aquatic insects can exchange gases partially through the cuticle and those fleshy projections help increase surface area for that to happen. I'll try to find a reference on that.

That would make sense.

Lateral Fleshy Projections
Increasing surface area for oxygen absorption does sound right. Maybe they also help to increase the friction between the animal and the sediment to fight the current?

Could be!
I just asked my professor (The famous Dan Young) and he says "They help with ventilation and also maybe with swimming."

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