Project Report

The order Tetraodontiformes is a group of roughly 350 species of fishes that has long attracted the attention of animal behaviorists and fish anatomists because of their exceptional ecological, behavioral, and anatomical diversity (Figure 1). Tetraodontiform fishes (e.g. filefishes, triggerfishes and pufferfishes) exhibit an exceptional range of skull bone and muscle modifications compared to the cranial anatomy of most fishes. The most profound example of these differences is several unusual subdivisions of the adductor mandibulae muscles that function in closing the jaws. While most fishes have three or four adductor mandibulae muscles, each family in the order Tetraodontiformes has a different number of adductor mandibulae muscles, ranging from two in spikefishes, to more than 10 in some filefish species. This differential skull anatomy among close relatives provides an ideal experimental platform for investigating questions about the evolution of multiply subdivided muscles, the physiological consequences of structurally complex musculoskeletal systems, and the neural control of architecturally complex functional systems. During the summer of 2011, I developed and carried out a research project that quantitatively compared the skull shape and jaw function of various tetraodontiform fishes native to Taiwan over 10 weeks in residence at the Academia Sinica. During frequent trips to local fish markets and by my own hook and line fishing efforts, I collected approximately 60 fresh fish specimens from 43 different tetraodontiform species, identified them to species, photographed them, and dissected their cheek musculature to characterize the jaw closing muscles and cranial anatomy of each fish. After importing photographs of each dissection to a computer, I digitally outlined relevant anatomical and functional landmarks of each fish skull, and compared all data collected using a suite of statistical tests. My results show that the skulls of fishes from the orders Diodontidae and Tetraodontidae (porcupinefishes and pufferfishes, respectively) are very differently shaped than fishes from other families in the order Tetraodontiformes (Figure 2). Furthermore, my data suggest that the lower jaws of porcupine and pufferfishes are significantly more forceful than other tetraodontiform fishes. Together with future analyses that will take place at my home institution, I hope to further investigate the functional and behavioral consequences of the complex jaw musculature of tetraodontiform fishes. My hypothesis is that these unique cranial modifications are due to the functional demands of a specialized diet. Pufferfishes and porcupinefishes are durophagous organisms, most commonly eating hard-shelled organisms, whereas other members of the Tetraodontiformes are typically generalist feeders. During the tenure of my EAPSI fellowship to Taiwan, and since returning to my home institution, I have had several opportunities to share my research and cultural experiences with scientists from other fields, and with the general public. While in Taiwan, I was invited to lead a "coffee chat" hour with summer high school and undergraduate research interns near the end of my visit to Academia Sinica. I introduced my research project and results, and led a discussion about comparative anatomy and functional morphology and how these topics are used in developmental and evolutionary biology (the two fields that the interns were most interested and educated in). Back at home, I have led two after-school activities with middle-school aged girls about fish ecomorphology using the results I obtained during my summer in Taiwan. After a brief introduction to fish skull anatomy and diet, the girls observed and dissected specimens I collected to Taiwan. Their goal was to use clues from their fish’s anatomy (teeth, jaw size, mouth shape, etc) to figure out what their fish eats. At the end of each session, each group of girls demonstrated their mastery of basic ecomorphological concepts by presenting their findings to the rest of the class.

National Science Foundation (NSF)
Office of International and Integrative Activities (IIA)
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Carter Kimsey
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Mccord, Charlene L
United States
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