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by
Robert H. Grant
School for Professional Studies
Saint Louis University
This case study was developed very soon after the death of Marjorie Courtenay-Latimer (1907–2004) in May of 2004. My hope is that it serves, in part, as a tribute to the legacy of her contributions to science.
The case study was developed for use in an introductory freshman biology course. In this setting, it could be used as a general introduction to the nature/methods of scientific inquiry at the very start of a semester or later in the semester as an introduction to the topic of evolution. Additionally, this case could be modified for use in a number of upper-level biology courses such as ichthyology (as a springboard into a discussion of ancient fish lineages or fish evolution), evolutionary biology (as an introduction to evolutionary relationships between classes of animals), or conservation ecology (as an illustration of the issues involved in studying rare animal species).
The case features photographs as well as fictitious diary entries interspersed with actual quotations from Marjorie Courtenay-Latimer’s writings to recreate the events surrounding Courtenay-Latimer’s ground breaking “discovery” of a living (non-fossil) coelacanth (Latimeria chalumnae) in 1938.
The case follows a progressive disclosure format with students receiving diary entries in two parts. Part I comprises a single diary entry that describes the day on which Courtenay-Latimer collected the first coelacanth specimen as well as a handout (Handout I) with a picture of what the fish would have looked like when Courtenay-Latimer first caught a glimpse of it in a pile of sharks, seaweed, starfish, sponges, and other fish on the deck of the Nerine. Part II is a collection of diary entries that chronicle communications between Courtenay-Latimer and her colleagues over the course of the next month and a half in her attempt to bring attention to her discovery. After each of these two parts, discussion questions are included. In the concluding part (Part III), students are given a list of facts and two additional handouts (Handouts II and III) that can be used in a number of ways to bring closure to the case depending on the instructor’s particular interest (see “Classroom Management” below for one approach).
Before the start of this case, arrange students into small discussion groups of three to five. This can be done randomly or non-randomly depending upon the instructor’s knowledge of group dynamics, student learning styles, or communication styles within the classroom.
The case requires no outside preparatory work by the students, and can be presented and discussed within a 50- to 90-minute class period.
Start the case by handing out Part I along with Handout I, giving the students 10 to 15 minutes to individually read the diary entry and discussion questions and peruse the photograph on Handout I. Then, give groups five to 10 minutes to discuss their answers to the discussion questions, first in their groups and then as a class, with the instructor (or students) recording the answers and observations on the board.
Next, hand out Part II and give the students another 10 to 15 minutes to read the diary entries and discussion questions. Again, allow five to 10 minutes for discussion of answers to questions, compiling and elaborating on answers as you go.
End the case by distributing Part III and Handouts II and III. I suggest reading the list of follow-up facts as a class so that you may steer the discussion in the desired direction (evolution, conservation, etc.).
Handout II is included to illustrate an overview of vertebrate evolution and to highlight the position of the coelacanth and its evolutionary relatives (i.e., Eusthenopteron) in this tree. In this vein, Handout II facilitates understanding that the discovery of a living coelacanth was a major scientific discovery from the perspective not only of evolutionary biologists, but for the human species as well. (Here the instructor should stress that what was found that day by Marjorie Courtenay-Latimer was not merely a fish, but a living example of one of our most distant evolutionary relatives.)
Handout III goes further to provide an image of a fossil coelacanth in which students can note actual anatomical features of the skeleton (in particular pectoral, pelvic, and caudal fin bone structure). Additionally, Handout III includes a recent photograph of a living coelacanth. This picture can be used as a segue into a discussion of ecological/biological issues surrounding the coelacanth such as overfishing, conservation, basic behavioral study, etc. You might even assign your students a small take-home project that involves researching at some greater depth the current status of global coelacanth populations, the evolutionary history of fishes, or any other issues pertinent to the case.
Use of this case can lead to discussions of several different topics, ranging from the scientific method to evolution to the historical role of women in science. Topics emphasized depend upon the educational goals of the instructor and the context in which the case is presented.
Coelacanths belong to Class Sarcopterygii. Other members of this class include both African and South American lungfishes (Subclass Dipnoi) and four-legged terrestrial vertebrates (Subclass Tetrapoda). While taxonomic classification of these fishes is in a state of perpetual flux, instructors should stress the evolutionary relationships of these groupings rather than the specific assignment of class or subclass to a particular group. The history of the coelacanth is useful knowledge to have before presenting this case.
Coelacanths are thought to have arisen in the early Devonian Epoch. Around 120 species of fossil coelacanths are known, most of which are thought to have gone extinct by the end of the Cretaceous. Fossil coelacanths have been found on every continent except for Antarctica, with the majority of these species occurring in fresh water. Close cousin to the coelacanth, Eusthenopteron, is the fossil fish species once cited as an intermediate form linking fish to amphibian species. Eusthenopteron and coelacanths share many anatomical features, the most important being the lobed fins that were thought to be the precursors to arms and legs in terrestrial organisms. As with the taxonomic classification of coelacanths, evolutionary relationships between coelacanths, Eusthenopteron, and modern tetrapods is also under constant debate and revision. Currently in favor are theories that name fossil species such as Icthyostega and Panderichthyes as the most immediate ancestors of tetrapods. Regardless of this theoretical fluctuation, studying coelacanths can help students learn about intermediate forms in the evolution and the appearance of new classes, families, and species.
Aside from learning about evolution through the study of coelacanths, the case provides students with a window into the scientific method and the nature of scientific discovery. Instructors should stress the fact that Ms. Courtenay-Latimer was not a trained fish biologist and that she very carefully researched her find and contacted pertinent authorities to obtain information. Also to be stressed is the fact that rather than an intimate knowledge of fish biology leading to her discovery, it was curiosity, an observant eye, and a good general sense of biology that led Ms. Courtenay-Latimer to her discovery. This is often the case with scientific discovery, and students will benefit by hearing about the “layman’s” role in science.
Another issue surrounding the coelacanth that others may find of use in their classrooms is conservation. Class discussion could be steered towards the ethics involved with collecting and studying potentially endangered species. Questions found at the end of Parts I and II facilitate discussion of this issue.
Finally, an issue brought up in the discussion questions that bears elaboration is the fact that the coelacanth was only “discovered” as defined by western science. As is the case with many scientific (and especially biological/species) discoveries, native peoples inhabiting areas in which the discoveries are made are often already familiar with the phenomenon. Depending upon the specific instructor’s goals, time may be spent upon alerting students to this culture-centric reality.
Please see the websites listed in the “References” section below for good background material concerning virtually all aspects of coelacanths and their discovery by western science.
Answers to the questions posed in the case study are provided in a separate answer key to the case. Those answers are password-protected. To access the answers for this case, go to the key. You will be prompted for a username and password. If you have not yet registered with us, you can see whether you are eligible for an account by reviewing our password policy and then apply online or write to answerkey@sciencecases.org.
Acknowledgements: This case study is based on work supported by the National Science Foundation under Grant No. 0341279 as part of the NSF-funded Case Studies in Science Workshop held at the University at Buffalo, State University of New York, on May 17–21, 2004. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
Date Posted: 06/24/05 nas
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