Odonates… pond-side treasures

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I admire people who have a wealth of knowledge and are generous in the way they share it with others.  Jim Johnson is one of those folks… he possesses a treasure trove of information about odonates: dragonflies and damselflies. Participants, like me, who attended his “Dragonfly Identification” workshop left feeling rich in new understandings about these fascinating arthropods.

Jim’s odonata gems of knowledge were shared in the classroom. Later, he showed us how to apply those “gems” of learning. We proceeded outside for a hike in search of damselflies and dragonflies. During our two hour quest for odonate pond-side treasures… the group explored several wet areas in Jackson Bottom Wetlands Preserve.

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the classroom: Introduction

In 1995, when Jim first became interested in these species, few formal field guides were available. He discovered much of what he knows from other odonata experts and countless hours in the field.  Fortunately for us, a number of Dragonfly and Damselfly resources have been written since then.

Here are some of his favorite recommendations- books with professional/academic points of view…to those more suited for the amateur entomologist:

Jim appreciates the scope of these insects on planet Earth. He explained that the more robust and greatest number of odonates are found in tropical regions with many others interspersed throughout diverse ecoregions, including a few species at home in the tundra.

A sampling of specimens from Jim’s personal collection were shared- dragonflies and damselflies from: Bolivia, Florida, Louisiana, California, Washington, and Oregon. These are just a few representatives from the 12 families of dragonflies and 21 families of damselflies known by entomologists.

More of Jim Johnson’s photography, regional checklist pdf files, and thoughts are also available on his websites:

the classroom: Natural history

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Odonata ancestry dates back to about 325 million years ago with the emergence of Griffin Flies- insects that had wing-spans of about 13 inches. Astonishing as that sounded, Jim also told of another ancient species with 27 inch wing-spans.

Either would have terrified me… I can still recall the “HUGE” dragonflies we ran away from as children! Now it’s funny to realize those very-scary-at-the-time dragonflies had wing-spans that were merely a small fraction of their extinct ancestors’ measurements!

Modern dragonflies and damselflies showed up on the Geologic Timeline about 200 million years ago during the Triassic Period. Their anatomy and life cycle characteristics have been sustaining this Order’s survival amazingly well.  Jim’s organized presentation provided a lot of background information about the anatomy, habits, life cycle, and reproductive processes characteristic in both dragonflies and damselflies. We discovered how species are grouped, and how to identify odonates common to the Pacific Northwest.

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Outside: The Capture
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Twelve-spotted Skimmer

It was the first sighting!

Jim patiently waited an appropriate amount of time for his followers to ohh… and ahh… at the first dragonfly spotting. Then- SWOOSH!!! Fast as lightning his net flew through the air. In a split second, he netted, and successfully pulled a male Twelve-spotted Skimmer from the bottom of the net.

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A good eye + accuracy + speed = A successful specimen capture

Outside: The Hold

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Once a dragonfly or damselfly was removed from Jim’s net, it was important to hold the insect securely and gently by the wings. Although these arthropods look very fragile and delicate, it was surprising to discover how durable and tough their exoskeletons actually felt. We all did our best to be respectful and careful none the less.

outside: sampling of species

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We viewed an impressive number of species in a variety of habitat locations. (The photos in this post are licensed by Jane Wilson/ Just Another Nature Enthusiast under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. You are free to use images. Please extend the courtesy of giving credit for any photographs you take to enjoy off this site.)

This list is a record of sightings Jim provided after the workshop:

Damselflies

  • Tule Bluet, Enallagma carunculatum
  • Pacific Forktail, Ischnura cervula
  • Spotted Spreadwing, Lestes congener

Dragonflies

  • Common Green Darner, Anax junius
  • Western Pondhawk, Erythemis collocata
  • Eight-spotted Skimmer, Libellula forensis
  • Twelve-spotted Skimmer, Libellula pulchella
  • Blue Dasher, Pachydiplax longipennis
  • Common Whitetail, Plathemis lydia
  • Variegated Meadowhawk, Sympetrum corruptum
  • Red-veined Meadowhawk, Sympetrum madidum
  • Cardinal Meadowhawk, Sympetrum illotum
  • Black Saddlebags, Tramea lacerata
outside: favorite pond-side finds

This last group of photos represent concepts Jim introduced that, as a naturalist in his class, I personally take away as my new gems of learning for the day:

Observing the complexities of damselfly reproductive behaviors was a remarkable opportunity.

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Although 100’s of eggs are laid in a single session, and 1000’s produced in a season… it truly is miraculous that there are odonates that actually live to maturity. The number of small fish feeding as the process was underway is enough to make a person wonder…

Pruinescence

This is a new science term for me- Pruinescense/ pruinosity- waxy bloom deposited on mature odonates of some species; apparently created by a waxy bloom that exudes from cuticle and turns it light blue, gray or white.

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Teneral damselfly

Jim helped me to understand this photo. I took it on May 7 in a wetland area north of Jackson Bottom. I was excited to learn that this is an adult pulling itself out of the exuvia. A newly emerged adult lacks pigment and is known as a teneral adult. A mature adult at this stage of development is not suitable to be captured for observation because the exoskeleton is still hardening and is sticky.

Pterostigma

This is fascinating…  See the darkened, narrow rectangular shapes at the top curve of each wing? Each wing has a pterostigma. It is believed to control flexing during flight and helps to weight the wing.


related website

Check out this URL for additional resources and a lead for a fantastic dragonfly ID app.

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     Click icon to link to site

 

Tendril Curves

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Tendrils-

How much thought have you given to these curvy plant structures?

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Since the nineteenth century, the curves of these specialized  vine structures have caught the attention of botanists. Some, like Charles Darwin, were puzzled by the technique many vines use to cling to their surroundings and to hoist themselves in search for sunlight. Darwin’s book published in 1865, On the Movements and Habits of Climbing Plants, is one of the earliest and most comprehensive studies of tendrils.

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Tendrils are used by climbing plants for: support, attachment, climbing, and cellular invasion (by parasitic plants) by twining around suitable hosts. They are specialized stems, leaves, or petioles with a thread-like shape.

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Grape vine tendrils grow opposite a leaf at the node.

When first formed, a tendril is almost straight, and while growing, it slowly waves around in a poorly understood process called circumnutation. When it encounters a foothold, the end of the tendril wraps around it, securing support.

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Tendrils are thigmotropic, which means that they are sensitive to touch. When they come in contact with a support, growth on that part of the tendril accelerates, forming the coil. Tendrils take on spring shapes and hold the vine tightly to the support. In fact, these coils can absorb energy, and are very helpful for the vine in strong winds.

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In 2012, a group of Harvard University scientists investigated the nature of tendrils coiling up into corkscrew-like helices- one right-hand coil the other a left-hand coil. Their discoveries reveal the mechanism and plant-structure composition that allow coils to twist without causing the plant to twist at the other end. Want to learn about the magic of how curves in plant structure make this possible? Click this link and watch a fascinating video: Scientists unwind the secrets of climbing plants’ tendrils


Science behind this post: (some facts in this post have been cut and pasted from these sites)

Parts of the Grape Vine

Scientists unwind the secrets of climbing plants’ tendrils

Up Close: Grape Vine Tendrils


Weekly Photo Challenge: “Curves

Invasive Himalayan Blackberry Removal / Weed Watchers

Friends of Glencoe Swale

Hand-tools, perseverance, sturdy clothing, tough shoes, and a good pair of leather gloves are what is necessary to tackle blackberry brambles. It also helps to have neighbors that are willing to lend a hand cutting, or able to give up yard debris containers.

This job was especially challenging because it was on a steep slope. And… to make matters worse, the vines were well established. Most were at least three-quarters of an inch in diameter. All crept over land, up tree trunks, over limbs and had anchor roots at the end of 15 – 30 foot long branching tendrils.

About eighty-percent of this patch was removed. Vines growing at the edge of the riparian zone were left because it is likely there are song sparrows and other small birds beginning to claim territory for nest-building. Clearing will continue in the late fall.

Native plants donated by Clean Water Services Native…

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