Loyola University Chicago

Department of Biology

Cheryl Theile Project Description

Title: Comparison of Feeding Functional Morphology Development in North American Esocids


Esocidae is a family of freshwater fishes within order Esociformes known for its long, cylindrical bodies, duck-bill snouts, and an impressive number of sharp teeth. There are four species, including two subspecies, in North America with areas of overlap of their geographic distribution. These ambush predators change diets from invertebrate prey to vertebrate prey during their first year of life, and the timing of this shift varies between species. In particular, the sister species Esox lucius (Northern Pike) and Esox masquinongy (Muskellunge) overlap in the upper Midwest, but E. masquinongy transitions to a vertebrate diet sooner in its development than E. lucius. This thesis focused on developmental changes of the lower jaw functional morphology and cranial geometric morphometrics and comparing those changes between two species: Esox lucius and Esox masquinongy. While both species follow a similar trajectory across development, E. masquinongy displayed traits consistent with faster lower jaw movement and a more streamlined cranium, both attributes helpful for ambush predators to effectively capture fast moving prey.


This work would not have been possible the assistance of the members of the Grande Lab. I’m not quite sure that Dr. Terry Grande knew just how big of a dream she was fulfilling by welcoming me into her lab and I know that I can never fully repay her for the opportunities she has given me. Dr. Mark Wilson helped improve my grammar and writing skills, while my fellow grad students helped boost my spirits and hone my dance skills to 80’s pop music during late nights in lab. In particular, my “lab brother” John helped keep a smile on my face with nerdy jokes and gave me opportunities to get muddy out into the field when I was fed up with dissecting scopes and cameras. In addition, fellow graduate students Ellen Cole and Lynika Strozier, while in other labs, supported me emotionally and with their computer software experience. I would also like to extend a special thanks to all of the undergraduates that worked with me at one point or another: Monica Rayner, Brandon Bernhardt, and especially my dear “Peduncle” Tetyana Sofiychuk. They helped take numerous photos and each made me a better scientist in their own way.

Thank you to the Loyola Biology Department. Dr. Marty Berg and Dr. Rodney Dale were valuable member of my committee. Dr. Berg was patient with my incessant questions during and after class, especially Biostats, and Dr. Dale’s contagious enthusiasm helped me remember my love of science during motivation slumps. Staff members Audrey Berry, Virginia Lorenzo, and Frank Inglima were all invaluable when I needed to file paperwork, send faxes, reserve rooms, or know when free food was up for grabs in the office- all vital to my experience as a grad student. My first two years were financially supported by the Graduate School and the remaining time was supported by employment within the Biology Department. I literally could not have done this without the financial support, thank you.

I would also like to thank those people outside of Loyola who helped me complete my research. Staff members of Illinois Department of Natural Resources’ Jake Wolf Memorial Hatchery, especially Steve Krueger, were essential in the collection of my development series specimens, and Kevin Swagel allowed me to use the radiological equipment at the Field Museum of Natural History.

Finally, I would not have been able to do this without the love and support of my family as well as my partner in crime, Manny Alvarez. I am forever thankful that my father, Greg Theile, set me on the right path by reading me articles from Scientific American as a child and taking me to spend weekend afternoons in the library reading about meteorology. While my love of science has changed topics many times over the years, he never ceased to support my endeavors and was even willing to earn his SCUBA certification to help me get a better look at the fish I love. My mother, Vanessa Theile, has helped me in more ways than I can count. So much so, that when I think of her love and support I truly am at a loss for words. Thank you, thank you a million times over. My sister, Valerie Theile, set the bar for accomplishments in our family very high; thank you for pushing me to be the best version of myself in my pursuit to keep up with you. Manny Alvarez, we certainly have been through a lot during our time in grad school. Thank you for believing in me when I couldn’t and for helping me get up when I fell. Thank you for not letting me settle for less than my best.



Cheryl Theile was born and raised in Cincinnati, Ohio. She attended Xavier University and University of Hawai’i at Mānoa for her undergraduate education, resulting in a Bachelor of Science in Biology with a minor in Chemistry from Xavier in 2007. During her break between undergrad and graduate school she worked as a biologist and presenter for the Newport Aquarium in Newport, Kentucky, as a veterinary assistant and lab manager for PetCare Animal Hospital in Cincinnati, Ohio, and as a surgical assistant for MedVet Medical and Cancer Center for Pets in Cincinnati, Ohio.

During her time at Loyola University Chicago, Cheryl served as President of the Biology Graduate Student Association, teaching assistant for Comparative Anatomy lab, instructor for General Biology Labs 1& 2, and counselor for the Biology Bootcamp. She presented portions of her thesis research at the Joint Meeting of Ichthyologists and Herpetologists in 2014 and 2016, and at the Midwest Ecology and Evolution Conference in 2015.

Cheryl is continuing her education at the Ohio State University College of Veterinary Medicine in Columbus, Ohio, and continues to feed her passion for ichthyology within the World Aquatic Animal Veterinary Association.



Dr. Terry Grande

Dr. Mark Wilson

Dr. Marty Berg

Dr. Rodney Dale