Wednesday, April 1, 2009
Arion species (unidentified)
This slug is so long and extensible - elastic! When resting it has a usual Arion shape, and can hump itself up into a rectangular lump when disturbed (which Arion circumscriptus cannot do), but while crawling, it just stretches longer and longer! In order to show an average aspect, I don't paint my slugs fully extended, so this portrait does not show this beast at its extreme, which is at least another 5 mm. It is not particularly shy, willing to wake up and walk about when nudged gently, or when its substrate is tilted or rotated. It had two wounds made by the fast, agressive little Deroceras panormitanum - luckily on the left side, as my portrait is of the side with the pneumostome. When I first opened the lid upon receiving the parcel from Washington state, I noticed one of the Deroceras following a slowly crawling Arion, and biting its tail! I immediately found several plastic sandwich containers and began to isolate all of the Deroceras, one to each box. I selected the largest Arion to begin painting, leaving the others in the thermos jug they were shipped in.
On March 14 I wrote to my family:
"Well, after a full day of painting, beginning at about 11:00 am, and finishing around 10:00 pm - I have the "mystery slug" painted, very frustrating because it wasn't even on my list of species for the book, and we're so close to the deadline. I couldn't leave it until after the deadline, however, because the nasty little dragon-slugs Deroceras panormitanum, which it was shipped with from Washington state, had taken chunks out of its left side and tail fringe, and that might have compromised its health in captivity.
Not a remarkably beautiful slug, but it was sent from Olympia, Washington with the other pale-footed slugs as Arion circumscriptus, along with yellow-footed Arion distinctus.... but the closer I looked as I began to draw it as circumscriptus, the more different it began to look from the other gray-footed slugs in the shipment.
Looking closely enough at a creature to paint it faithfully is fascinating, literally! .... and looking at a creature that the specialists shrug and turn their palms up at (our coauthor Robert Forsyth did that too), is an irresistable challenge.
I photographed both kinds of gray-footed Arions, and made a list of their differing characteristics for most of one day, and spent most of the next day (yesterday) drawing the larger of them - and correcting my drawing - and correcting it again, countless times! I had begun by copying my painting of Arion distinctus, because I was told that it was similar, but with a gray foot. But by the time I was finished adjusting that drawing, it looked considerably slimmer than distinctus, and with more rows of tubercles. Its lateral line does arch over the pneumostome (breathing hole) as it is supposed to do in circumscriptus, but that doesn't make it circumscriptus. The other slim Arion slug I've painted is A. fasciatus... but this one is even slimmer than that, and fasciatus has a yellow foot besides.
It could be another European introduction, even one that is not found in Canada and therefore doesn't belong in our book - who knows! I will send it to Robert to dissect. Perhaps DNA analysis can be done at some point. I am beginning to think like a taxonomist about Arion slugs.
Only a few days ago I was expounding the basic philosophical wholesomeness of taxonomic work to Corey in the kitchen. Taxonomists are the 'namers', giving us information about the distinctness of living things, one from another. Providing us with names with which to know them, and care about them - so we can make decisions about whether it is wise to step over them in the woods or necessary to pave them over for commercial developments. In the book of Genesis, God instructed Adam to name the plants and animals He had made, as part of his position as steward in the garden of Eden. Author of fantasies Ursula LeGuin describes the education of wizards on the Isle of Roke - the last and most difficult task before they are considered mature wizards, responsible enough to change the shape of anything, is to learn the true name of each kind of living thing. Responsible members of any community learn the names of their neighbours. It is part of 'caring'. The name of our neighbour serves as an essential reference for thinking, learning, and communicating about that neighbour. Every creature whose name we know becomes a part of us.
Today I told Fred that I think I've found 'my taxon' - the kind of creature that I am most curious about the names of.... Arion slugs! They are a most convenient group to work on, living nearly everywhere, You can find the ubiquitous alien Deroceras reticulatum eating gardens everywhere too, but there are nearly always some kind (sometimes two or three kinds!) of Arion slug along with them. Arions don't chase and bite other slugs like Deroceras laeve and Deroceras panormitanum, so they will be easy to keep groups of them in captivity. Slugs lay eggs readily, and they usually hatch successfully without much attention except sufficient mosture. Their generation times are short, so breeding experiments are convenient. They stay healthy on damp paper with Romaine lettuce to eat, and egg shells for calcium. I look forward to learning how to dissect them - a finicky, tedious procedure for determining internal differences in genetalia, that I thought I'd never be interested in doing. But when one has found one's taxon, nothing is too finicky for finding the differences that matter to the species themselves!
Fred regaled the staff of the Brigadoon Restaurant about our recent malacological adventures, as he and Matt were there this evening after checking the Oxford Mills dam for Mudpuppies. He said they stood around, mouths open in awe, hearing things they'd never imagined, as he described the intensity of the efforts of our team to arrange for the collecting and importation of live slugs for me to paint. This afternoon he commented to me that he'd better sharpen his spade, to beat off other men, as my taking up Arion taxonomy was the sexiest thing he'd ever heard of.
Another thing about taking up a taxon, is that although it is a time-consuming pursuit, there are no deadlines. No-one can tell how long it could take to discover the name of a thing, so one just works on it in whatever time one can find.
I don't think my new passion will be complicate my life unduly, as I would only spend time on it when I have time for it. Picking up slugs doesn't take much time, and neither does making sure they all have fresh lettuce. They are easy to kill and preserve, and the collection doesn't take up much room either. Though painting them would take some time......
Anyway, it's past bedtime. I'll be drawing Arion circumscriptus tomorrow.
distinctly black-speckled, tan-to-grey mantle & back
dark reddish-black tentacles
sides neutral pale grey
mantle sides tannish grey below lateral line
foot wide (spindle-shaped body)
foot pale grey
foot fringe very pale yellow
tail abruptly tapered to a point
These are the characters I noticed as I was painting this shy, gentle slug, not yet quite sure of its identity. Sometimes it is good when one hasn't put a creature "in a slot", because then you take more careful note of everything about it. This is definitely Arion circumscriptus according to my slug experts Bill and Robert.
The Arion circumscriptus were all smaller than the slug I'd just painted, and they rested on a wet surface with their foot fringes spread out in a skirt, giving their oval bodies almost a limpet shape. They were also liberally freckled with black. When I finished the portrait of the large slug (which I am calling the "Mystery Arion") and began to draw the Arion circumscriptus, I was impressed with its shyness. Prodding it never resulted in a resumption of activity. I just had to wait, tilting the substrate gently, and holding it under the light. The shy little slug eventually decided to get up and move to a more peaceful spot, and so I got to photograph it, and to watch it closely to paint.
Next I painted the Deroceras panormitanum that had been chasing my poor Arion circumscriptus around and taking bites out of it.
I made some interesting observations while working with these slugs (I used two of the four you sent (one died upon arrival, and was preserved promptly).
Although they are sluggish on damp leaf litter in their containers, these "racing slugs" become very active, and 'run' very fast when put on a foreign substrate, like the flexible plastic ruler I use while painting. During the course of the "live sitting", I can't take my eyes off one of these fast slugs for more than a few seconds at a time, because it creeps about a centimetre per second toward the edge and drops off. A couple of times, when ambling rather than running, D. panormitanum has gone over the edge leaving a strand of slime attached to the edge, and dangling head-down, descended slowly.
The first time, the slug slowed to a stop at about 10 cm below the edge of the ruler. After waiting for about a minute, twisting and spinning slowly only 3 centimetres above a lettuce leaf, cupping its foot so that the fringe edges looked like the blades on a weirdly flexible bobskate. Then it began to swing its head and neck from side to side in "U" shapes 8 or 10 times, before making contact and climbing up its own body and then up the slime strand, which by this time had dried and become very thin, like a single strand of spider silk. It climbed up the strand, rather than eating it, and in about 15 seconds, was up over the edge of the ruler.
The second slime-strand was much longer, measuring about 25 cm. I had someone hold the ruler for me as I tried to get some photos, but the slug was swinging and the camera wouldn't focus on it. This time the slug dropped a few centimetres to the dark blue tablecloth, rather than climbing back up the strand.
These "racing slugs" run very far on the flexible ruler during the course of painting, and when they begin to look a little dry and desperate, I give them a rest in their container while I continue to paint, referring to photos, or take a break myself.
On one of these occasions the slug had made a dash for freedom just as I pressed the lid on its container, and got trapped in the groove of the lid for twenty minutes or so, until I opened the container to resume painting. The poor slug looked rather deformed, but it straightened itself out somewhat as it crawled slowly under a leaf, so I left it to rest for a few hours. On checking it later, I noticed it curled in a "U" shaped position, and then it reached for the side of its tail and began a licking motion. After 7 or 8 'licks' it turned away, and there was an opening in the previously unbroken brown skin, a fresh gap about 1.5 mm long, revealing the translucent grey flesh beneath. My best guess is that the slug had excoriated its bruise - if it were not mistaking its own side for the wounded flesh of another slug, it was perhaps aiding its own healing by making a fast-healing cut where there had been a slow-healing bruise.
This afternoon, as I packed the slugs up after finishing the painting, I peeked inside each apartment. I was pleased to see the wounded slug looking plump and active, albeit with a slightly shortened and dented aspect to the left side of its tail - the wound appeared to be healing over. In the second slug's container, where it rested in the dark damp space between two dead leaves, there were about 15 newly-laid eggs, clear as glass. Peeking again at the wounded slug just before closing the lid, I noticed a tiny, slim figure of a minute slug, only 1.5mm long - a greyish pink baby Deroceras panormitanum (couldn't have been an Arion, as their hatchlings are quite plump). It was crawling quite quickly, so I reached for my camera, but by the time it was turned on and set to macro, the little one had disappeared. Racing Slugs!
Later I wrote to Bill Leonard:
"It is difficult deciding on an aspect for a slug, when it looks so different when first discovered, slippery with slime, and when its been crawling and dry. Also, whether it's contentedly moving, or dashing, neck full out. My mental image of D. panormitanum now, after having spent so much time with it, is different than I have it in the painting. It is reaching, neck arched like a little racehorse, tentacles stretched to thinness, and foot narrowed for speed. Quite a different aspect than the placid one I have painted. That's why I particularly wanted to see if you recognized its likeness in the painting". (He answered that the position I have painted it in is recognizable and quite appropriate.)