01 August 2014

A crab across the decades: the changing face of scientific illustration

When I recently published a paper (full text on DoctorZen.net) about finding a sand crab (Lepidopa websteri) where it hadn’t been before, I wrote about the images of the crab I found in a nature center. But I got thinking about how this crab has been shown in scientific papers.

The scientific literature on this crab is the almost only place where you will find images of it. A search of Google Images reveals only one page with pictures of the species (a googlewhack!) and that’s in the larval state. There are no pictures of adults except my own blog posts.

Because this species is obscure, I was able to do something that you can’t do very often: compile what may be absolutely every image of the species shown in the scientific literature. Click to enlarge:

It’s fascinating to compare the different images, for their use of technology, and the pros and cons of each representation.

Benedict 1903: The carapace is prominent and easy to see, but while this line drawing is clear, it ignores most of the animal.

Hay and Shore 1918: The black and white photograph is frustrating, because in the text, they note:

Color, in alcohol, probably also in life, pure white, but everywhere beautifully iridescent, giving pearly reflections at every turn of the body.

I read that description and I want something so much more than the picture of a damaged individual! I want to see the beautiful colours they are writing about! In fairness, the original picture on paper may be better than the scan shown here, but it would still be black and white.

Pearse et al. 1942: This picture may be the most elegant representation of L. websteri from an artistic point of view. There is some beautiful brush and ink work on display here. And while I wish the species name was set in italics, I am still attracted to the handmade warmth of the letters.

Scientifically, though, there’s one big mistake.

The caption lists the appendages below as the five walking legs. Nope. The first one, over on the left, is one of the mouthparts, not a leg. I know why this happened, though: this crab is a relative of hermit crabs (infraorder Anomura). All the crabs in this group share a feature: their fifth pair of walking legs are very small, and in sand crabs, tucked underneath the tail.

Boyko 2002: Technology has moved on. You can see an incredible increase in the level of detail and precision in these images, facilitated by digital cameras and graphics software. These images are invaluable for identification and technical work. They are very much in line with the sort of represented used by Benedict back in 1903.

But they show an “exploded” animal, with none of the parts in relation to each other, and no images of the prominent antennae.

World Birding Center 2009: I’m cheating a little, because this picture isn’t in the scientific literature. But it is in a professional nature center and museums generally strive for images that are scientifically accurate and engaging. This one is... neither. It looks like it was drawn from a very old specimen preserved in alcohol, or other images, rather than a living animal.

Faulkes 2014: These are, as far as I know, the first colour photographs on an adult L. websteri in the scientific literature, or even the Web. Now, you can finally get a sense of the beautiful pink overtones and iridescence that Hay and Shore mentioned.

The other thing I’m happy about with this figure is that it shows the whole, live animal, with everything in context. You can get a sense of the very first thing I noticed about this animal, which helped me recognize instantly that it was something different: the length of the antennae.

Update, 16 June 2016: Found a wonderful photograph of this species on Flickr. It’s much better than my own. I think it was taken after mine (February 2014) but posted before my paper was published. I can’t embed it here because it does not have a Creative Commons license.

Related posts

Way down south: stumbling across a sand crab (Lepidopa websteri)


Benedict JE. 1903. Revision of the Crustacea of the genus Lepidopa. Proceedings of the United States National Museum 26(1337): 889-895.

Hay WP, Shore CA. 1918. The decapod crustaceans of Beaufort, N.C., and the surrounding region. Bulletin of the Bureau of Fisheries 35: 369–475.

Pearse AS, Humm HJ, Wharton GW. 1942. Ecology of sand beaches at Beaufort, N. C. Ecological Monographs 12(2): 135-190. http://www.esajournals.org/doi/abs/10.2307/1943276

Boyko CB. 2002. A worldwide revision of the recent and fossil sand crabs of the Albuneidae Stimpson and Blepharipodidae, new family (Crustacea, Decapoda, Anomura, Hippoidea). Bulletin of the American Museum of Natural History 272(1): 1-396. http://dx.doi.org/10.1206/0003-0090(2002)272<0001:awrotr>2.0.CO;2

Faulkes Z. 2014. A new southern record for a sand crab, Lepidopa websteri Benedict, 1903 (Decapoda, Albuneidae). Crustaceana 87(7): 881-885. http://dx.doi.org/10.1163/15685403-00003326

No comments: