The following photo shows a tiny spider carcass (~3/16″ long) that was inside an exuvia (~1 3/4” long) from a Common Green Darner dragonfly (Anax junius). The exuvia was collected on 17 June 2021 from a small pond in Prince William County, Virginia USA. I discovered the spider long afterward — too late to save its life.
Thanks to Eva Weiderman and Joseph Girgente — members of the “Odonate Larvae and Exuviae” Facebook group — for their help in identifying the specimen as a jumping spider, Family Saticidae.
Salticidae is one of several families of spiders with eight (8) eyes. My take-away from reading the reference on BugGuide entitled “Spider Eye Arrangements” is identification of this specimen to the genus and species level is challenging at best and impossible at worst.
In contrast, it’s well known that spiders use odonate exuviae for shelter. I wish the jumping spider had come out of its most excellent hidey-hole sooner!
“Raynox DCR-250 close-up filter” is a blog post in which I provide more information about how I use the Raynox with my Panasonic Lumix superzoom bridge cameras.
The following product photos show the bottom of Godox X2T-series wireless flash triggers for Canon, Fujifilm, and Olympus/Panasonic digital cameras. The pin pattern on the flash triggers is the mirror image of the pin pattern on the camera hotshoe.
Notice the pin pattern varies by camera brand. One pin — the power pin — is located in the same place on all types of flash brands. The other pins are used to control functions such as Through The Lens flash metering (TTL) and High-Speed Sync (HSS). This is why almost any relatively new external flash unit can be used in Manual mode with almost any relatively new digital camera, but TTL and HSS are incompatible unless the flash is mounted on the hotshoe of a camera with a matching pin pattern.
Cross-compatibility among Godox TT-685-series external flash units
The beauty of the Godox system of external flash units is it’s truly a system — all units that I own and have tested extensively are cross-compatible.
For example, when a Godox TT685F for Fujifilm cameras is used off-camera it can be fully compatible with a Godox TT685O for Olympus and Panasonic cameras (including TTL and HSS functionality) when it’s fired by a flash trigger such as the Godox X2TO. It’s amazing to watch!
The following quick-and-dirty video is another demonstration of the cross-compatibily among Godox TT685-series external flash units.
A Godox TT685F flash for Fujifilm cameras is featured in the preceding video. The flash was fired remotely using a Godox X2TO wireless flash trigger for Olympus and Panasonic cameras.
An Apple iPad mini 2 was used to shoot a raw video clip that was post-processed using Apple iMovie. The magic wand tool in iMovie was used to automatically enhance the audio and video quality of the clip. Audio quality was improved significantly by the magic wand tool!
The mystery item featured in my last blog post is a Christmas tree ornament hanging above a battery-powered flashlight with a low-power incandescent bulb.
Perhaps the bigger mystery is what makes the gold propeller inside the ornament spin around when the flashlight is powered-on.
Christmas tree ornament hanging above a flashlight.
Energy Transformations
When I taught 8th grade Physical Science classes, “energy transformations” was an overarching theme in one of the lab manuals for the course.
The Rayovac No. H22 Industrial Flashlight (shown above) uses two 1.5 V D-cell batteries to power a 2.4 V incandescent bulb. When the flashlight was powered-on and placed below the Christmas tree ornament, the following energy transformations occured.
potential energy → chemical energy → electrical energy → radiant energy → thermal energy → kinetic energy
Knowing that kinetic energy can be thought of as energy of motion, the question remains: What gives the spinning propeller its kinetic energy?
Heat Rises
How many times have you heard this common misconception? “Heat,” more correctly referred to as “thermal energy,” flows from higher to lower concentration of thermal energy, regardless of directions such as up or down. So what causes the propeller to spin?
Thermal energy from the incandescent flashlight bulb causes the temperature of the air around the flashlight bulb to increase. The warm air around the bulb is less dense than the surrounding air so it rises; the rising air current causes the gold propeller inside the Christmas tree ornament to spin. It’s worth noting I removed the plastic “lens” from the face of the flashlight head so it wouldn’t block airflow from the light bulb to Christmas tree ornament.
The Backstory
The Christmas tree ornament shown above is a treasured memento from my early childhood. My parents bought two similar ornaments: one is blue with a gold propeller; the other is green with a red propeller (not shown).
One of the ornaments was a gift for my sister; the other was for me. I can’t remember which one was given to me. In my defense, that was a long time ago — I might have been as young as three or four years old when we got the ornaments. That said, I remember clearly how fascinated I was with the spinning propeller inside the ornament!
At that time, Christmas tree lights were relatively large colored incandescent bulbs that got uncomfortably warm-to-hot when powered-on. When my Christmas tree ornament was hung above one of those lights, the propeller spun much faster than it did when hanging above the smaller flashlight bulb used for my demonstration.
The mystery item featured in my last blog post is a Beetle Spin® 1/8 oz fishing lure.
Beetle Spin® 1/8 oz fishing lure.
Perhaps the bigger mystery is how the fishing lure ended up where I found it, stuck in the bark of a tree (about head height) quite a distance from a small stream that might be fish-less. There was no fishing line attached to the lure. Anyway, there it was.
Beetle Spin® is one of the classic all-purpose fishing lures that is a nice addition to my tackle box.
For some species of odonate exuviae, sex is indicated by a form of remnant reproductive anatomy. These external structures don’t look exactly the same for all species of dragonflies and damselflies, but their function is identical.
The following photograph shows a ventral view of a femaleCommon Green Darner dragonfly. Notice the external reproductive anatomical structure on abdominal segment nine (S9) is virtually identical to the remnant anatomical structure on S9 of the exuvia, shown above.
Original photo used with permission from Louisa C. Craven.
The Backstory
My dear friend Louisa Craven discovered the lifeless adult dragonfly while on vacation with her family in Nags Head, North Carolina USA. Louisa is an accomplished wildlife photographer who developed an interest in odonates as a result of many photowalks with me.
This subject was photographed against a pure white background (255, 255, 255) using the “Meet Your Neighbours” (MYN) technique.
During this photo shoot, I tested the Flash Diffuser Light Softbox by Altura Photo (6″ x 5″) for the first time. This relatively inexpensive softbox ($12.99) is highly recommended by Allan Walls, an excellent photographer who specializes in macro photography. I must admit I was more than a little skeptical but the diffuser seems to work as advertised and is a remarkable bargain, unlike my expensive Lastolite softbox flash modifiers (8.5” x 8.5” square).
The 1:1 rule-of-thumb is used to determine how close/far to position a flash unit from the subject. The diagonal distance across the face of a softbox should be the distance to the subject [or less] for soft wrap-around light. Actually, the distance should be as close as possible without the softbox showing in the photo frame. Greater distances will result in a contrasty look.
For example, my new Altura softbox is a 6” x 5” rectangle (7.8” diagonally) so it should be positioned ~8″ or less from the subject. Buyer beware: This distance is OK for macro photography but not OK for most other types of photography.
The rule of thumb for differentiating Corduliidae exuviae from Libellulidae is as follows: It’s probably Corduliidae if the cerci are at least half as long as the paraprocts; it’s probably Libellulidae if the cerci are less than half the length of the paraprocts.
65mm (3x magnification) | ISO 100 | f/8 | 1/200 s | 0 ev
Look closely at the full-size version of the preceding photo, showing a close-up of the anal pyramid at 3x magnification. Notice the cerci are approximately half as long as the epiproct and slightly less than half the length of the paraprocts. It’s a close call, but the latter field mark indicates Family Libellulidae (Skimmers).
A step-by-step identification guide (to the species level) will be published in a follow-up post. Stay tuned!
Spot-winged Glider and Wandering Glider larvae/exuviae look similar. The lateral spines on abdominal segment nine (S9) are noticeably shorter for P. hymenaea (shown left) than P. flavescens (shown right) — a key field mark that can be used to differentiate the two species.
A Spot-winged Glider dragonfly (Pantala hymenaea) exuvia was collected by Andy Davidson near Richmond, Virginia USA.
A Wandering Glider dragonfly (Pantala flavescens) exuvia was received from Andy Davidson, graduate student at Virginia Commonwealth University.
The Backstory
Both specimens featured in this blog post were collected (near Richmond, Virginia USA) and identified by Andy Davidson. Andy is a graduate student at Virginia Commonwealth University working on a research project entitled “Predator-Prey Interactions in a Changing World.”
Master Yoda’s explanation of the Force to Luke Skywalker (see Related Resources, below) features the following memorable quote.
Luminous beings are we,
not this crude matter.
One of many reasons I like the “Meet Your Neighbours” technique for photographing natural subjects against a pure white background is that it seems to reveal the luminous beings that odonate exuviae are. Feel the force by looking at the full-size version of the following image.
walter sanford's photoblog 