Vertical tubes in pond sediment - Phylocentropus

Moved

Moved from Caddisflies.

Thanks Lloyd--I have ruled out all the other options to my satisfaction, and this seems like a reasonable match.

… Charley Eiseman, 27 March, 2009 - 6:25pm

A vote for Phylocentropus

I'm not very familiar with other orders that might build similar structures, but I think that Phylocentropus is a pretty strong candidate. Per the size issue discussed below, although these larvae can be fairly long, they are also extremely slender. For what it's worth, you can compare your images with the tubes and associated larvae pictured here.

… Lloyd Gonzales, 27 March, 2009 - 6:07pm

Moved to Trichoptera...

...in hopes of getting an opinion from one of the caddisfly connoisseurs.

… Charley Eiseman, 6 February, 2009 - 6:24pm

Phylocentropus?

So, according to Wiggins (2004), Phylocentropus live in "bottom sediments of lakes and depositional zones of streams." (So edge of pond seems fine)

Also, it sounds like these could be broken off old side-branches of a tube sustem:
"A bulbous portion of the side-branching tube encloses a sack-shaped filter net of silken threads randomly arranged. Extensive systems of tubes with more than one bulbous side branch are often found in the sediments (Figure 12), but usually only one is functional and the others are sealed off at the junction with the main tube." And the tubes in figure 12 look a lot like yours, the bulbous portion being the base of the side branch.

… Noah Charney, 6 February, 2009 - 8:27am

...

Yeah, I remember that those are supposed to have a bulbous portion--I'm not sure why I didn't mention that above. I wish I had found intact branches to confirm... The way these tubes were all roughly vertical and about the same length didn't seem to match--his illustration shows the bulbous-bottomed branches coming out at an angle and just barely peeking above the surface--but there doesn't seem to be anything else that comes close to this. They sure aren't worm tubes, and midges don't seem to make anything this substantial. The fact that Phylocentropus can be found at the edges of lakes is encouraging.

… Charley Eiseman, 6 February, 2009 - 8:49am

The texture seems identical,

The texture seems identical, and Wiggins' newer drawings show old buried branches, presumably because the surface level shifts (the old buried branches used to be exposed?), so it seems like the height and angles probably vary...

… Noah Charney, 6 February, 2009 - 10:45am

Does he say anything about size?

Does 3 mm wide seem reasonable?

… Charley Eiseman, 6 February, 2009 - 10:49am

it seems pretty small for a caddisfly, perhaps the tubes you found are all early instars that start off with one unbranched tube, and would be smaller. Wiggins describes the larvae of the family (Dipseudopsidae) as "long and slender ranging in length up to about 20mm." Measuring dimensions on his drawing and scaling down, that would make a max diameter of the larva 2mm. So maybe those are the right size.

Also, "The total length of a tube system may extend up to some 16cm and is perhaps longer still." - I think thats if you add up the lengths of all the branches.

… Noah Charney, 6 February, 2009 - 6:47pm