Analytical photography
I've had a wonderful exercise in class today doing analytical imaging of specimens. Here's some pieces of taxidermy (and a rock) photographed under UV (ultra-violet) lighting - a blacklight.
First up: a peregrine falcon (Falco peregrinus). Using a hand-held UV lamp first, my partner and I saw the legs, face and underside of the wings fluorescing. Unfortunately our photo setup did not allow us to showcase the underside of the wings, but that could have been attempted with a different plan - and would have, if we were only photographing the one specimen. I do not believe the specimen has been painted, but that's a commonly used trick in bird taxidermy, as skin tends to lose its colour as it dries. The fluorescence can also potentially stem from pesticides or other chemicals used in conservation, such as glue (the flourescence under the wing is most certainly glue), but it would require further testing to say for certain.
Next up: the Atlantic wolffish (Anarhichas lupus). This is quite frankly a beautiful mount of the fish! It's lost its colour over the years, but the UV-flourescence completely distracts from that fact. Our lecturer suspects it may be coated in a form of tree sap-based varnish, since this tends to flouresce blue-green as it ages. If you look closely on these images, you can see metal tacks holding open the fins, and ventrally along the tail you can see a seam for closing the skin around the form.
Finally: calcite. And what a finale it is! UV fluorescence is a common ID-trick for minerals as some shine really brilliantly, and this chunk of rock really shows how that works. In daylight (this photo is lit only from one side, to better show the surface texture) the mineral is a plain white colour, but the UV-lighting brings out a red and purple shine from deep inside it. We were joking that it looks like a video game asset as we set up the photo! I've used UV for geological specimens before, but only in microscope slides.
