Category Archives: Education

Conference poster full of tips for creating conference posters

In case you need a quick guide to making a conference poster, here are two versions of my poster of poster tips. They have content overlap, so just choose the layout that pleases you. More details below the images.

Poster example (Colin Purrington's)Advice on designing scientific posters

Both posters are descendants of a document I created circa 1997 for my evolution students at Swarthmore College. The bottom one is available as a PDF if you want to print an actual poster of it — which I highly recommend if you are assigning a poster project for your class (students don’t like reading the website, below).

My full tips are at Designing conference posters. I created the website for my students, too, but eventually made it public in case it might help make the world’s poster sessions more enjoyable and their posters easier to understand. Please share with your friends.

Etymology of garter snake

Colin Purrington Photography: Reptiles &emdash; Eastern garter snake (Thamnophis sirtalis sirtalis)Even though “garter snake” has been the common name for Thamnophis sirtalis for over 200 years, I discovered this week that people who know a lot about garter snakes don’t agree on why. There are two theories: (1) the snakes were named after stocking garters and (2) sirtalis is the Latin word for stocking garters and thus the common name was derived from the Latin binomial. I know, not a burning question for most, but I was curious given that snake fans seem to choose one or the other without further mentioning why. So I looked into it.

Garter holding up a woman's stocking (from The Practical Costumer)

Photograph of an embroidered garter. Image from the The Pragmatic Costumer (click image to read her article).

(1) Most articles, books, and websites explaining the common name suggest it’s because the snakes resemble garters, pieces of fabric that were fastened right below one’s knee (the garet, in Celtic) to keep stockings from falling down (that used to be a huge problem). The resemblance is lost on most people today, especially guys who don’t know their lingerie history, because garters are now frilly and made of silk or satin and thus not at all snake-like. But back in early Europe they often had lines and patterns that could easily remind somebody of the stripes and scales of a snake. And everyone wore them: women, men, even kings, so they were ubiquitous, visible, and probably conversation starters. So it’s not surprising that somebody eventually referred to a particular type of snake as a “garter” snake. 

In etymology it’s important to establish when a particular word first appears, so I consulted the Online Etymology Dictionary and learned that garter snake first shows up in 1775, in the United States. The Online Etymology Dictionary says the name is related to stocking garter but doesn’t provide proof of this or any links. Curious, I found that “garter snake” shows up even earlier, in 1773, in a description of specimens in somebody’s collection in Lichfield, England. Again, there is no explanation of why the common name was garter. I’m sure the first usage of “garter snake” goes back even further, too, if you had access to a good database of letters and newspaper articles from the time. I don’t.

(2) A potentially related hypothesis for the common name is that sirtalis means “like a garter”. This is exactly the claim thousands of scientists and naturalists make. If true, then the common name might have been launched when Linnaeus published his classification in 1758. Alternatively, maybe it just confirms that he knew of the common name and simply applied the Latin cognate for the species. But I was suspicious of this claim because when Latin was a living language there weren’t stockings or the need for garters. Sure enough, when you look up sirtalis in a Latin dictionary, it’s not there. Like many of words Linnaeus used in his binomials, he made it up by combining Latin and Greek roots, leaving us to guess at what the new word might mean. Kraig Adler theorizes that the word might be a combination of siro (Greek for cord, rope, or string) and talis (Latin for such, the like), and thus might mean “ropelike”. So when people claim that sirtalis means “like a garter”, they are incorrect. The first appearance of the “like a garter” claim seems to in 1976, in Robert Parker Hodge’s Amphibians and reptiles in Alaska, the Yukon, and Northwest Territories. I don’t own the book so I’m not sure if he cites somebody, in turn.

Although sirtalis does not mean “like a garter”, I guess it’s possible that Linnaeus had garters in mind when he concocted a rope-like species name for the snake. He probably wore garters, and perhaps called these snakes “garter snakes” before he officially named them. The question, then, is whether the common name predates his scientific name. In looking into this I discovered a second common name that I think was borrowed from German or Dutch: kouse band. The French use serpent jarretier (jarretier means garter), and Swedes use strumpebandssnok. Anyway, it seems that everyone in 1790s Europe, regardless of language, called them snakes-that-look-like-garters. Would be nice to know which language first started to call them by the respective name, but to do that I think I’d need something other than Google’s English-based book search. Note that the 1773 date I mentioned above was found with Google, and thus is probably simply related to my usage of the English-language version. There are likely other databases out there without such language problems.

A deservedly rare explanation for how the garter snake got its name is that it is a misspelling of guarder snake, garden snake, gardener snake, or garten snake. Some of these variants are quite common on the internet, and I think most people can blame their parents.

Small winter stonefly

I was out looking for the elusive snow fly yesterday but found this, instead: an eastern stonefly (Allocapnia recta), a member of the Capniidae (small winter stoneflies). At least that’s what I think it is. Larvae are active during the winter, and adults can fly and mate even when temperature is in the teens. Pretty incredible to see them flitting around on a cold day when other insects cannot even move. At Hildacy Farm in Media, PA. Probably emerged from the nearby Crum Creek. 

Colin Purrington Photography: Insects &emdash; Eastern stonefly (Allocapnia recta) Colin Purrington Photography: Insects &emdash; Eastern stonefly (Allocapnia recta)