Friday Harbor Students Find Creepy Crawlers

by Alex Patia.

Friday Harbor 6^th grade students arrived Wednesday last week to a chilly but beautiful late autumn day here at the Environmental Learning Center. The big leaf maples (Acer macrophyllum) are mostly bare now and their bright yellow leaves now decorate the ground covered with leopard-like dark dots created by tar spot fungus (Rhytisma punctatum). Whenever the clouds clear the surrounding mountains Sourdough, Ruby, Pyramid and Colonial become visible and reveal a snow line creeping lower and lower in elevation. It feels as though it shouldn’t be too long before the snow finally sticks down here too and the Lake Diablo area is transformed into a winter wonderland with snow coated Douglas firs and white hills.

My trail group, the Lynx, were already making great observations their first day, noting changes from dry Lodgepole pine forest up by Bust Brown field down to the comparatively lush riparian forest alongside Deer creek. During an “Each-One, Teach-One” lesson students learned from and taught each other about various types of water quality tests, environmental factors that effect riparian health and how numbers of macroinvertebrates (animals without backbones visible to the naked eye) can tell us about water quality by whether or not they are pollution tolerant or pollution intolerant.

Students started off their second day developing a question related to water quality, using the scientific method, which they could research out in the field. My group was interested in finding whether or not dissolved Oxygen (DO) and pH were tied at all to how many benthic macroinvertebrates could live there. Their method involved each student looking under 5 cobble (fist sized) rocks to find and collect macroinvertebrates, or as we dubbed them “macros”. After looking at a map of the area students decided to conduct research at Fawn and Sourdough creeks.

A trail group at work on Fawn Creek. 

At Fawn creek students were having trouble finding macroinvertebrates at first, but upon closer inspection many of the rocks they had collected had some well-hidden macroinvertebrates moving about. The most visible were little worm-like creatures that inched about like leeches, which made some of the students a little uneasy about reaching into the water, but the arrow-shaped creepy crawlers turned out to be planarian or flatworms (Class Turbellaria). Students were puzzled by some mysterious empty cases made up of very tiny pebbles, and as they wondered where they came from some students noticed that when probed a creature’s head would wiggle out one end of the case and wave it’s legs as if to complain about the disturbance. Using the dichotomous key in their field journals the students came to the conclusion that these were the case-building larvae of Caddisflies (Order Trichoptera). The pH test showed the streams water was a neutral 7 but the DO test did not end up working, too many air bubbles may have been the problem.

Trail groups examine macroinvertebrates using ice-cube trays for collection. 

At Sourdough the only macroinvertebrates collected were Caddisfly larvae, which once again were difficult to spot looking like just tiny clumps of gravel at first and about half the time these cases were no longer occupied. Part of this lack of macroinvertebrate diversity could likely be that just a few weeks ago this creek was completely dried up. Once again the pH turned out to be neutral and students opted to skip the seemingly fickle DO test.

Back at the microscope lab students took a closer look at the macroinvertebrates they had collected. One macroinvertebrate collected from Fawn creek was too small to identify earlier but under the microscope turned out to be a Fishfly larva (Order Megaloptera), a predator with a menacing pair of mandibles- when viewed through a microscope. Students were curious to see if this Fishfly larva would try to eat a flatworm so we placed them in the same dish. The Fishfly did indeed try to bite the flatworm but the much larger flatworm pushed the larva out of it’s way after a brief albeit dramatic struggle.

Poking around looking for various creepy crawlers from amphibians to macroinvertebrates has always been my favorite past time. Most people I hike with quickly grow tired of waiting as I search under each and every accessible rock or log trying to find these seldom seen or appreciated creatures, but the students from Friday Harbor were just as excited as I was to find out what was lurking under each rock. Thank you Friday Harbor students for being willing to get cold, wet and muddy in the name of science and exploration! I hope you will visit the North Cascades again but don’t forget there are many places to explore right in your own backyard where there are rock and logs with all sorts of creepy crawlers hiding under them waiting to be found!

Photos by Jessica Newley.