Thursday, August 20, 2015

Boating in the Fog

We often get thick morning fog, on Caesar Pond, that slowly burns off as the day advances. This was one of those mornings. I began my outing by turning around in a circle, to show you the fog, before taking the boat to the north end of the pond where I was looking for wildlife. I often see beavers, snapping turtles, painted turtles, and a variety of birdlife there. 

This morning, I was joined by Neighbor Carla (who often accompanies me on my nature adventures.) We heard the call of a kingfisher, but it never came close enough to view. We did, however, see an Eastern Kingbird, which I videotaped. This is one of my favorite pond-dwelling birds, and I am always treated to observing them in the larch trees at the north end of the pond.

Due to the heavy mist in the air and dew on the grasses, we also saw thousands of spider webs covering virtually every surface of the islands of the bog. They added to the mystique of the morning.

We checked out the beaver lodge and the small dam at the northern edge of the pond. The beaver works continually to keep the dam in shape so that the water doesn't drain out of the pond. (Ummm...I get rather silly when in the boat with Carla, and some of my "non-scientific speak" makes her laugh, hence the silly dialogue...;-)

The only other wildlife that we observed were hundreds of waterbugs, which Drew identified as Water Striders (Aquarius remigis), in the true bug family Gerridae. These speedy bugs are so fascinating. Drew had to slow their movement down by 50% so that you could catch a glimpse of them in the video. I found this information in Wikipedia about them:

Water striders are able to walk on top of water due to a combination of several factors. Water striders use the high surface tension of water and long, hydrophobic legs to help them stay above water. Water molecules are polar and this causes them to attract to each other. The attractive nature results in the formation of a film-like layer at the top of water. This top layer has gravity acting downward in addition to the water molecules below pulling down the upper molecules. This combination creates surface tension.

Gerridae species use this surface tension to their advantage through their highly adapted legs and distributed weight. The legs of a water strider are long and slender, allowing the weight of the water strider body to be distributed over a large surface area. The legs are strong, but have flexibility that allows the water striders to keep their weight evenly distributed and flow with the water movement. Hydrofuge hairs line the body surface of the water strider. There are several thousand hairs per square millimeter, providing the water strider with a hydrofuge body that prevents wetting from waves, rain, or spray, which could inhibit their ability to keep their entire body above the water surface if the water stuck and weighed down the body.[4] This position of keeping the majority of the body above the water surface is called an epipleustonic position, which is a defining characteristic of water striders. If the body of the water strider were to accidentally become submerged, for instance by a large wave, the tiny hairs would trap air. Tiny air bubbles throughout the body act as buoyancy to bring the water strider to the surface again, while also providing air bubbles to breathe from underwater.[4]

The tiny hairs on the legs provide both a hydrophobic surface as well as a larger surface area to spread their weight over the water. The middle legs used for rowing have particularly well developed fringe hairs on the tibia and tarsus to help increase movement through the ability to thrust.[4] The hind pair of legs are used for steering [9] When the rowing stroke begins, the middle tarsi of gerrids are quickly pressed down and backwards to create a circular surface wave in which the crest can be used to propel a forward thrust.[4] The semicircular wave created is essential to the ability of the water strider to move rapidly since it acts as a counteracting force to push against. As a result, water striders often move at 1 meter per second or faster.[10]

“Gerridae.” N.p., n.d. Web. 

[4]Ward, J.V. (1992). Aquatic Insect Ecology: 1. Biology and habitat. New York: Wiley & Sons. pp. 74, 96, 172, 180.
[9] Williams, D. & Feltmate, B. (1992). Aquatic insects. CAB International. pp. 48, 121, 218. ISBN 0-85198-782-6.
[10]Andersen, Nils Moller & Cheng, Lanna (2004). "The marine insect Halobates (Heteroptera: Gerridae): Biology, Adaptations, Distribution and Phylogeny" (PDF). Oceanography and Marine Biology: an Annual Review42: 119–180.