Current Program: Ph.D. in Biology

B.S. in Biology (Summa Cum Laude with Distinction) (Marine Emphasis; Minors: Environmental Studies, Geoscience) - Southeast Missouri State Univeristy - May 2003

My research interests are centered on ichthyology, specifically elasmobranchs. I am interested in elasmobranch ecology, behavior, feeding morphology, and sensory biology. My current research is focused on the feeding and head morphology of hammerhead sharks (Sphyrnidae). The relationship between form and function can be used to determine the biological role of a given feature.  The study of this relationship, functional morphology, has received considerable attention over the last forty years.  By interpreting form and function of phylogenetically closely related organisms a better understanding of the selective forces and constraints that govern their diversity can be obtained.    One form of constraint is constructional constraint, whereby spatial limitations are placed on a structure, such as the hammerhead cehalofoil, as a result of multiple biological roles (e.g. respiration, feeding, sensory reception).  This is particularly important when considering the size and position of sensory and feeding organs.
The dorsoventrally compressed and laterally expanded pre-branchial cephalofoil of hammerhead sharks offers a unique opportunity to study adaptation in an historical context.  By interpreting form and function of a closely related group of organisms, such as hammerhead sharks, in a historical context we can gain a better understanding of the selective forces and constraints that govern the diversity of cranial design.  The shape of the cephalofoil ranges from extremely wide (E. blochii – 40-50% of Total Length [TL]) to only moderately expanded (S. tiburo – 18-25% of TL), with concomitant changes in the chondrocranium, jaws, cranial musculature, and neural and sensory apparati.  Genetic evidence indicates that the sphyrnid with the most laterally expanded cephalofoil is the most basal, with cephalofoil size decreasing through phylogeny.  Various hypotheses have been posited to explain the adaptive significance of the peculiar hammerhead shark head morphology including: increased hydrodynamic lift, prey manipulation, enhanced binocular vision, greater olfactory gradient resolution, and enhanced electroreceptive area.
The goal of this study is to examine the evolution of sphyrnid head morphology and the correlated changes in the sensory and feeding systems.  The following hypotheses will be investigated: 1) Inclusion of less elusive and harder prey in the diet of more derived species results in greater bite force, an increase in the mechanical advantage of the jaw, and hypertrophy of the jaw apparatus and cranial muscles; 2) Consequently, the spatial constraint imposed on the cephalofoil which becomes less expanded through phylogeny, will result in an increase in relative volume devoted to feeding structures and a concomitant decrease in relative space devoted to sensory structures and their repositioning on the cranium (eyes, nares, mechanosensory pores, and ampullae).  These hypotheses will be addressed in a phylogenetic context using four functionally and morphologically disparate extant hammerhead species (E. blochii, S. mokarran, S. lewini, and S. tiburo) and three fusiform shark outgroups (Rhiziprionodon terraenovae, Negaprion brevirostris, and Scyliorhinus canicula). Other hammerhead species will be used if available.

For more information about my dissertation research see my Research Plan.

In the past I have performed research on lamprey ammocoetes from the species, Lampetra aepyptera. This is a small non parasitic stream species that is commonly found in shallow clearwater streams in the midwest. I used histological techniques to describe the ultrastructure of the eye as it relates to the process of metamorphosis. I also examined population structure and phototaxic behavior through the use of field collections. This research was performed while at Southeast Missouri State University in corporation with Dr. Rex Meade Strange.

I have also participated in numerous research projects during my undergraduate and graduate careers including: 1) examining the effect of temperature, salinity, and depth on species (Croaker, Micropogonias undulates, Spot, Leostomus xanthurus, White Shrimp, Litopenaeus setiferus, and Blue Crab, Callinectes sapidus) composition, 2) examining the feeding kinematics of juvenile bluegill sunfish., Lepomis macrochirus.  

For more information about my previous research experiences see my online Research Bio.

Mara, K. R. and P. J. Motta. (In Prep).  Phylogenetic investigation of head shape in hammerhead sharks (Sphyrnidae).

Motta, P.J., Maslanka, M., Hueter, R.E., Davis, R.L., De la Parra, R., Ulvany, S.L., Habegger, M.L., Strother, J.A., Tyminski, J., Mara, K.R., and Gardiner, J. (In Prep).  Feeding anatomy, filtering rate, and diet of whale sharks Rhincodon typus off the Yucatan Peninsula Mexico.

Mara, K.R., P.J. Motta, and D.R. Huber. (In Submission).  Bite force and performance in the durophagous bonnethead shark, Sphyrna tiburo.

Lowry, D., A. Castro, K. Mara, L. Whitenack, B. Delius, G. Burgess, and P. Motta. (In Submission). Identification of shark size from forensic analysis of bite damage.

Motta, P.J., R.E. Hueter, T.C. Tricas, A.P. Summers, D.R. Huber, D. Lowry, K.R. Mara, M.P. Matott L.B. Whitenack, and A.P. Wintzer. (2008).  Functional Morphology of The Feeding Apparatus, Design Constraint, and Suction Performance in the Nurse Shark Ginglymostoma cirratum.  Journal of Morphology 269: 1041-1055.

2007   National Science Foundation grant: “Collaborative Research: The Function and Evolution of the Hammerhead Shark Cepahlofoil”.  Co-wrote with Philip Motta, Stephen Kajiura, and Andrew Martin Co-PIs.  $233,937

2004   New Graduate Student Summer Support Grant.  Mara, K.  University of South Florida.  $5,000

2003   Undergraduate Research Grant.  Mara, K. 2003.  Photosensitivity in Ammocoetes (Agnatha) of the Least Brook Lamprey, Lampetra aepyptera.  Southeast Missouri State University. $900

2002   Undergraduate Research Grant.  Mara, K.  Photosensitivity in Ammocoetes (Agnatha) of the Least Brook Lamprey, Lampetra aepyptera.  Southeast Missouri State University. $500

Mara, K.R., P.J. Motta, and J.A. Pfeiffenberger.  Constructional Constraints In Sphyrnid Sharks: Shape Change And Space Utilization Through Phylogeny.  The Society for Integrative & Comparative Biology.  Boston, MA.  3-January-2007.

Mara, K.R. and P.J. Motta.  Constructional Constraints In Hammerhead Sharks: Shape Change And Space Utilization Within The Cephalofoil. 88th Annual Joint Meeting of Ichthyologists and Herpetologists.  Montreal, Quebec, Canada.  23-July-2008.

Mara, K.R., P.J. Motta, and D.R. Huber.  Bite force and performance in the durophagous bonnethead shark, Sphyrna tiburo.  The Society for Integrative & Comparative Biology.  San Antonio, TX.  2-January-2007.

Mara, K.R., P.J. Motta, and D.R. Huber Durophagy in the bonnethead shark, Sphyrna tiburo: an ecomorphological conundrum.  87th Annual Joint Meeting of Ichthyologists and Herpetologists.  St. Louis, Missouri. 12-July-2007.

Mara, K.R. And P.J. Motta Morphometric Head Shape Comparison Among Hammerhead Sharks (Sphyrnidae). The Society for Integrative & Comparative Biology.  Phoenix, Arizona.  3-January-2007.

Motta, P., R. Hueter, D. Huber, D. Lowry, K. Mara, M. Matott, L.B. Whitenack, and A. Wintzer.  (2005).  Suction performance and feeding biology of the nurse shark Ginglymostoma cirratum.  85th Annual Joint Meeting of Ichthyologists and Herpetologists. Tampa, Florida.  6-July-2005.

Motta, P., R. Hueter, T. Tricas, A. Summers, M. Matott, D. Lowry, K. Mara, L.B. Whitenack, and A. Wintzer.  (2004).  Functional morphology, suction performance, and the enigma of protrusion in the nurse shark Ginglymostomata cirratum.  7th International Congress of Vertebrate Morphology. Boca Rotan, Florida.  29-July-2004.

Mara, K.R. and R.M. Strange.  (2003).  Eye Ultrastructe in Ammocoetes of the Brook Lampreys (Lampetra).  11th Annual Southeast Missouri State University Student Research Conference.  Southeast Missouri State University, Cape Girardeau, Missouri.  17-April-2003.

Mara, K.R. and R.M. Strange.  (2002).  Eye Ultrastructe in Ammocoetes of the Brook Lampreys (Lampetra). Indiana Academy of Science 118th Annual Meeting.  Butler University, Indianapolis, Indiana.  11-October-2002.