Monday, February 13, 2012

Creek Creatures

The temperatures may be well below freezing, but as long as the water remains ice free, I can enjoy watching aquatic creatures going about their business on the bottom of the creek.  On this sunny day, Caddisflies were busy dragging their stone casings around as they grazed algae and other morsels from the rocky stream bottom.

If I’m going to observe aquatic animals in the creek, it’s got to be done in the winter and spring.  Lack of water in the summer and fall makes it difficult to find those animals that maintain an aquatic existence.  During the wet phase, the creek is full of easily observed life.  I assume that these species are adapted to life in an environment that annually cycles between wet and dry.

Caddisflies use sand to adorn the silken sack in which they spend their larval stage.  This camouflage allows them to blend quite well into the rocky creek bottom.

Patterning of the mayfly larvae makes them hard to notice as they move across the substrate.  Their shape resists the drag of the passing water and allows them to avoid being easily swept downstream.

The creek supports several species of snails.  Snails spend the dry season beneath stones or buried in the gravel stream bottom.

Snails feed on algae scraped from the rocks.  Consumed material moves quickly through the snail’s gut and is expelled as nutrient rich pellets.  This process converts the energy of the algae into a form usable by many other organisms.  Without animals like the snail, there would be no fuel to sustain the animal life of the stream.

There were a lot of tiny creatures that I wasn’t able to identify.  I imagine that they will become more recognizable as they grow.  Temperature was at 23 degrees and wind was about 15 mph so I didn’t remove any of these animals from the water.  I didn’t think exposure to that cold air would do them any good and I didn’t want to freeze my fingers in the process of capturing and examining the little guys.

Isopods were a childhood favorite of mine.  I was intensely interested in paleontology and in my mind the aquatic isopod was as close as I could get to a living trilobite.  I used to keep a few in a jar on my dresser and spent hours watching them.  Watching these scavengers forage across the rock face reminded me of those days spent observing my captive specimens.

These animals spend most of their time hidden beneath the rocks.  It was interesting to see them out going about their normal business in the bright sunlight.

Planaria have always survived in the smaller tributaries, but it was just a few years ago that I first saw them in the main creek that passes through Blue Jay Barrens.  Planaria need clean, well oxygenated water and disappear quickly if water quality deteriorates.  Concentrations of cattle in the watershed above Blue Jay Barrens used to add a high nutrient load to the water, causing rapid growth of algae in the creek.  The cattle have gone and the water quality is more typical of a natural stream.  This has allowed the planaria to successfully move from the tributaries to the main creek.


  1. Hi Steve...I must say you sure do love to get to the bottom of things don't you lol!!!!!
    The creepy crawler the better!!
    I love your dancing deer herd from yesterdays post !! : }

  2. Hi Grace. I guess I just find bottoms more interesting than tops.