Friday, September 14, 2012

Windsocks in the River

No, this underwater photo is not of my son meeting a water snake,

 but rather, the windsock-like catchnets of the tube-making caddisfly larvae I mentioned last post. The silk nets billow in the current, causing them to change shape now and then.
 The caddisfly larvae that weave these catchnets are commonly called trumpet-net caddisflies - referring to the trumpet-shaped nets with their tapering tubes and flared openings.
Many of these insect-sized fishing nets (if I may call them that) are fastened to rocks, woody debris, and vegetation in this section of the West Branch Susquehanna River.
   Trumpet-net caddisfly larvae (Neureclipsis) weave these recurved silk nets as a means of collecting food.
The gaping mouth of the net allows river water to enter and the silk net filters out detritus, plankton, and other organisms.  The larvae live in the silken retreat and subsist on the collected food particles.
   I'm impressed with the trumpet-net caddisflies.  For one reason, the quantities of underwater silk that they spin.  Another reason is how they weave these looped catchnets right in the current.  Thirdly, I'm impressed how the caddisflies set up shop with their nets and utilize the food resources that are just passing by on the current.
Above - a photo of a caddisfly net that is hung in the gap between two river cobbles.
Below - a collection of caddisfly nets hanging on vegetation and rocks.
  When I see these wide-mouthed monsters ravenously devouring the river, I wonder what percent of the river's water gets sieved?
By the abundance of these billowing nets, it's apparent that they do a whale of a good job sieving food particles from the river.
   Anyway... the river flows on...
What else can we find hidden under the water's surface?


  1. Loving the under-water shots Dana.

    My education continues.

    Did you like the apple I left on your desk ?

    1. Sybil,
      Great! We'll be visiting the river again.
      The nice thing about some apples is they can sit on a desk and look good for a long time. Thanks!