Back to posting: Seastar Video

It has been a long time. Here, to get things rolling again, is an awesome little video (with English subtitles) that SDU made about the discovery my students made (unexpectedly) and my friends and I helped them publish. The part at the end where the starfish squeezes out the tag through its skin in slow motion is pretty damn cool.

Olsen, T. B., Christensen, F. E. G., Lundgreen, K., Dunn, P. H., & Levitis, D. A. (2015). Coelomic Transport and Clearance of Durable Foreign Bodies by Starfish (Asterias rubens). The Biological Bulletin, 228(2), 156-162.

If you want to hear more about this process and how awesome my students are, see this post and this post and this post.  Oh, and especially this post here.

Good practice

Always order paper reprints for your undergraduate coauthors to give to their parents.

Ear to Ear

Yesterday, two students came to my office. They asked me to help them organize a BioBlitz, a rapid assessment of what species are present, at Svanninge Bjerge, the site where I taught my field course this spring. One of these students was in that course, the other I have seen around but don't really know. I asked all the basic questions. What do you envisage? Where will you do it? When? How will it be funded? We had a good long conversation, and I offered what support I can, while making clear I may no longer be in Denmark when this all happens. They frowned. I asked, "Where did you get the idea to do this? Why do you want to?" They looked at each other. The one I don't know, smiled sheepishly. "Well, I couldn't take your course last year. And after the course, all the students who did take it made all of us who couldn't fell incredibly jealous. They talked about it endlessly, like it was everything they could ever want in a course. Like we would go to a bar and instead of whatever we were talking about, they would be all about pinning beetles. Rather than fight about it, we agreed to try to organize something similar for ourselves. And it would really be great if you could be involved." I needed a moment to focus on maintaining my composure.

Student scientists study sea stars, produce plaudable publication

A good university science education should give students the opportunity to engage in scientific research. This is widely agreed upon, and most of the biology position announcements I consider state that the successful applicant's research should present opportunities for student participation. The general model is that the professor has the research program, and a question that needs answering, and a plan for answering it, and the student gets to see how research happens by carrying out, or at best refining, that plan. I'm all in favor of this, but I'd like to take it a step further.

My first publication, way back in 2003, was with one of my professors at Bennington College, based on work that she planned, and I, as an undergraduate, helped carry out. I made alterations to the experimental protocols, did a lot of lab work with minimal supervision, and chose to work on this project rather than others that were available, but I can take no credit for any of the ideas in the publication. In retrospect the one thing I would add to my own undergraduate education, if I was to be my own professor, was working through the entire process of generating a primary paper, from initial observations and idea generation to publication.

Implausible you say? Impracticable? If generating publishable science is so easy, why doesn't every professional scientist publish a paper a week? Well, I've just finished doing it with two of my students, and I'll tell you about it.

'Finished' is vague. We've submitted the paper, and I think it good, but we have to wait to hear if the reviewers agree. I'm not going to give you too much detail on what we found because you'll have to read the paper (or a future post) when it comes out.

It happened like this: At SDU, where I currently work, all natural science students in their second semester have to complete a group project. A group of students (four in my case) are assigned a faculty mentor who gives them a question to answer and guides them in answering it. In my case, the question was, "Can we use PIT-tags (like a vet puts in your cat) to mark starfish for a long-term demographic study?" We brought some starfish into the lab, talked about animal care and experimental design, showed them how to inject the tags and pretty much let them do their own thing.

They did great, but the tags just kept coming out. After a few weeks, all the tags were out. They answered my question with confidence: No, PIT-tags cannot be used to mark starfish long term. But the thing is, they didn't stop there. With no pay, no additional course credit, no requests for recommendation letters or such, two of the four students just decided to keep going. We met occasionally and I offered encouragement and comments, but little more.

They presented their results to the Evolutionary Demography Society, and long after the course was over they kept doing more experiments to figure out how the starfish were ejecting the tags. Notice that this is their own question. I asked, "Do the tags stay?" and my students answered this then asked, "How do they get rid of the tags?" And when we had an open house at the laboratory, they presented what they had learned to the public. Just by chance, one of the visitors they talked to had access to an ultrasound machine. This let them repeatedly image exactly where within the starfish the foreign body was moving. A year after they started, they convinced me that they had discovered, and had the data to back up, a previously unknown mechanism by which starfish can eliminate foreign objects from within their body cavities. "Okay," I said, "write it up for publication, and tell me now by what date you will have a finished draft." They missed their self-assigned deadline. They needed more help with data analysis than they expected. They put in all the wrong references in all the wrong places, and the flow of the article was terrible. English is not their first language. But not so long after they said they would, they sent me a draft that had most everything I needed to make it good. With the co-authorship of a couple of marine biologists (did I mention that I know next to nothing about starfish and have no other starfish research ongoing?) and with the continued input of these two students, we made a respectable manuscript out of it.

What lessons do I draw from this? Motivated undergraduates, with just enough guidance, can basically have their own successful research programs. The paper we produced still took a bit of my time to write up, and isn't the most important paper in the world, but they discovered something completely new (answering a question that someone who knew the literature would never think to ask), and they learned. They learned a lot. Refining questions. Starfish anatomy and function. Experimental design and practice. Ultrasound imaging. Cox regression in R. Scientific English. Literature searching and use. Collaboration. Communicating science to peers and the public. Preparing and submitting a manuscript for publication. Now they will get to see how peer review really works, or doesn't. These students, just starting their third year as undergraduates, have a fuller experience of what goes into making a scientific publication than I did when I started my third year as a doctoral student. Chew on that for a minute.

It is important here to think about these students' motivation. Judging by their grades, they are not academic stars. Neither of them has described a lifelong fascination with starfish. They did this, so far as I can tell, because it was their first chance to truly be scientists rather than just science students.

I told them early on that:
A) That they would have a strong say in the direction of the research and
B) that if they produced something publishable, I would help them submit it for publication.

These are not promises to be made lightly. Publishing things, especially things outside one's own central line of research, is time consuming. Giving first year undergraduates even this limited version of academic freedom in their research is, understandably, not common practice. But it seems to me to be damn good educational practice, and I plan to continue offering this type of opportunity to students when possible. Students will do much better, and more, work when they are exercising agency and following their own curiosity. Even if they don't choose careers in science, they know how science happens from start to finish, and that is surely something science students should be given the chance to learn.

Better measures of tiny bits of living jelly

My student and I had a paper accepted last week. I like this paper a lot. First some official details, then a short story about how the paper came to be.

Forthcoming in "Marine and Freshwater Research" 

The consistent, non-destructive measurement of small proteiform aquatic animals with application to the size and growth of hydra 

Daniel Levitis and Josephine Goldstein

Abstract: Hydra (Cnidaria), the basal metazoan most often studied in cellular, molecular and developmental biology, is difficult to measure because it is small, proteiform and aquatic. To facilitate broader organismal and ecological study of Hydra, we evaluate three methods whereby a polyp's body column can be measured by means of photomicroscopy. The volume, cylindrical surface area and surface area corrected for changes in body shape are all highly repeatable methods (r=0.97) when shape varies little. However, shape changes alter volume and cylindrical surface area. Repeated corrected surface area measures of the same individuals in markedly different positions yield standard deviations that are less than 5% of the mean measured area. This easy, non-lethal means of individual size measurement explicitly accounts for the flexible morphology of a polyp's hydrostatic skeleton. It therefore allows for the elucidation of how growth and size vary over time, age and food intake. We find that hydra change size dramatically day to day, and that while food level influences adult size, it has little effect on the early growth of recently detached buds. Finally, we discuss ecological and biological applications of this method. 

Part of why I like this paper so much is that my student did most of the hard parts, and the reviewers didn't ask for a lot of changes, and the editor (Dr. Russell Death) moved things along quickly and efficiently, so it is the first paper I've published that didn't feel like pulling my own teeth. It is a solid methods paper. It says, "here is a method for doing something that many scientists may want to do, that we didn't know a good way to do before."

In particular, it is a simple way to accurately and easily measure a tiny transparent aquatic animal with no hard parts or consistent shape without harming it.  Take a picture of it and with a bit of simple math calculate its surface area. Simple, elegant, inexpensive, non-invasive, biologically meaningful, everything I hoped it would be.

But the method presented in the paper is a substantially different, and better, method than the one we started out with. In fact, we were almost ready to submit the paper when we changed the method drastically.

I started out just wanting to measure a hydra polyp because it was necessary for another research project. Nobody had a method that worked halfway decently without killing the hydra. A hydra's body, although it shortens and lengthens, bends and twists is almost always roughly a deformed cylinder. So I said, "Hey Josi" (that's my student), why don't we develop a method to measure a hydra by photographing it and estimating its volume as though it was cylinder?" She agreed, and off we went, taking photos of hydra during our whole research project, for almost two years. We finished gathering our data, and found that indeed we could measure hydra this way. It didn't work great, but it kinda worked. You could use it to tell the difference between a really huge hydra and one that was just kind normal. Viola, unimpressive but probably publishable methods paper.

We wrote it up and were pretty close to submitting when I decided to see what hydra focussed papers had come out recently, and found that someone else had just published almost the exact same method in a nice paper with an interesting biological point. Our formulation of that method didn't work any better than hers did, and we had no point beyond "here is how to measure." We couldn't publish the same method again, even if we came up with it independently. After some cursing and self-recriminations for being so slow, I decided to see if it was possible to salvage anything of the methods paper. Josi took another set of photos and I used them to repeatedly adjust my formula, with limited biological reasoning, until something worked better than the formula just published. In fact, one formula I came up with by eyeballing my graphs worked much better than the method just published. So much better that the calculated value hardly changed at all even when the shape of the hydra changed drastically.

Now you are probably saying to yourself that this is blatant cheating. Trying different formulas (perhaps 100 of them) until something gives you the result you want is a pretty sure way to get the result you want, if you are persistent enough. But two things combined to make this not just okay, but beautiful. First, the formula I stumbled upon made obvious biological sense, even before I knew it worked. This formula represents a hydra as a roughly cylindrical bag whose skin stretches as it elongates itself, or folds and ripples as it contracts. In other words, it describes a hydra accurately and reveals something I didn't previously know about the way a hydra moves. Secondly, and as importantly, when I applied the formula to the main data set, which I didn't use to develop the formula, it still gave a highly consistent measurement for any individual, even as the shape of the individual changed. The method in fact works for completely different populations of hydra. You could take two hydra that looked the same size under the microscope and conclusively decide that one was bigger than the other. You could tell how much a young hydra grew each day. You could really measure the buggers, eliminating most of the noise inherent to previous methods.

Still more lovely, the method Josi and I had just developed could make use of the photos and measurements we had already taken, so redoing all our calculations and figures required Josi to write only a few extra lines of code (Thank you Josi, thank you R). We did a little rewriting to compare our method favorably to our other method, blamed attributed the other method on to the person who had just published it, made our biological argument to explain why the method worked, and we had a drastically improved paper ready to submit. There is a lesson in this somewhere about the scientific method.

Unboiling letters of recommendation

Laboratory work, especially demographic laboratory work, is labor intensive. (Perhaps that is why it is called a laboratory?) I couldn't do the experiments I do without lots of reliable helpers. At the Institute where I work, and at most universities I've seen, much of this labor comes from eager young undergraduate students. They work hard (if carefully chosen), want to learn and don't cost a great deal.

This is the last week I will employ most of my wonderful mob of students, and so today I am writing letters of recommendation for almost all of them. I've gotten to know most of them quite well, and I like all of them, so it shouldn't be such a hard task. But of course I have found a way to make it hard. I feel I owe it to them to write a memorable individual letter for each person, not a formulaic boilerplate with a few details changed. And while their personalities are very different, many of the positive things I can say about them in these letters are all the same, leading to boilerplatedness. I suppose the need for creativity within constraints such as these should be taken as an artistic challenge.