People


 PRINCIPAL INVESTIGATOR 
C_Marshall Christopher Marshall, Ph.D.
Associate Professor

Email: marshallc@tamug.edu
Phone: (409) 740-4884
Dr. Christopher Marshall is the PI of the lab. His work focuses on integrating morphology, physiology, and behavioral performance of feeding in marine vertebrates to provide information regarding an organism's foraging ecology, and their conservation. This work includes investigations of natural history and comparative neurobiology of sensory systems of marine vertebrates.
 CURRENT LAB MEMBERS
Josh Cullen Josh Cullen
P.h.D. Student
Josh Cullen is a doctoral student in the Department of Wildlife and Fisheries Sciences and is the recipient of the Merit and Excellence Fellowships.  Josh completed his B.S. in Biology at Clemson University and recently published his undergraduate research in the PLoS One.

 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0053274
Erin Mattson Erin Mattson
M.S. Student
Erin Mattson is a master’s degree student in the Marine Biology IDP Graduate Program.  She finished her B.S. in Ecology and Evolution at Rice University and completed an undergraduate research thesis entitled, “Juvenile Competitive Bottleneck Dynamics in a Cyclopoid Copepod (Mesocyclops edax)"
 FORMER LAB MEMBERS
B_kot Brian Kot, Ph.D.
Post-doctoral scientist
Dr. Kot has a professional background in engineering and biology, and completed his PhD in Ecology and Evolutionary Biology from the University of California, Los Angeles (UCLA) in 2009.  His research focuses on behavioral ecology and conservation of marine mammals and fishes, and incorporates various aspects of comparative physiology, functional morphology, bioacoustics and physical oceanography.  Some of his work has recently been published in Journal of Experimental Biology, Journal of Experimental Marine Biology and Ecology, and Marine Mammal Science.  It has also been featured in the popular press, online and on international television programs (e.g., BBC – Earth News, Discovery Channel’s Animal Planet program).  He also has strong interest in developing experimental research technology and recently designed an underwater remote sensing system consisting of video cameras, an acoustic recorder array and various oceanographic monitoring equipment.  Dr. Kot also has considerable teaching experience and has earned multiple teaching awards including the A.M. Schechtman Award for distinguished teaching at UCLA.  
Lori Timm Lori Timm
P.h.D. student
The specialized behaviors and sensitivity to environmental changes exhibited by sea otters makes them useful as a management-indicator species, and a useful tool in promoting the protection and health of ecosystems. Benthic foraging by sea otters is an important component of their natural history, and substantially influences their environment. However, little is known regarding their feeding adaptations and feeding performance. Therefore, the overall goal of this project is to investigate the feeding capabilities of sea otters to begin to understand the costs of foraging, as well as, the ecological role the sea otter plays in a coastal community. The ecomorphology of feeding in sea otters will be investigated by integrating behavioral and kinematic studies of both wild and captive sea otters, with bite performance testing, measures of jaw muscle physiology, and craniodental morphological analyses of specimens in natural history collections. The specialized behaviors and sensitivity to environmental changes exhibited by sea otters makes them useful as a management-indicator species, and a useful tool in promoting the protection and health of ecosystems. Benthic foraging by sea otters is an important component of their natural history, and substantially influences their environment. However, little is known regarding their feeding adaptations and feeding performance. Therefore, the overall goal of this project is to investigate the feeding capabilities of sea otters to begin to understand the costs of foraging, as well as, the ecological role the sea otter plays in a coastal community. The ecomorphology of feeding in sea otters will be investigated by integrating behavioral and kinematic studies of both wild and captive sea otters, with bite performance testing, measures of jaw muscle physiology, and craniodental morphological analyses of specimens in natural history collections.
Alyssa Alyssa Marsh
M.S. Student
Bottlenose dolphins (Tursiops truncatus) are distributed worldwide and are among the most frequently studied cetaceans yet little information is currently known about their life history in the wild.  This statement is especially true for the North-Central Gulf of Mexico (NCGOM) region even though studies of bottlenose dolphins have been conducted since the mid 1970s.  While there have been some advances, important questions such as age-at-length, age-at-weaning, ontogenetic shifts in prey sources, distribution, as well as foraging patterns have yet to be answered.  Stable isotope analysis of carbon and nitrogen will be conducted on bottlenose dolphin teeth to answer these questions.  Growth layer groups (GLGs) in teeth are an informative tissue that provides a permanent record of the individual’s diet over its lifetime.  These layers are also determinates of age, growing one additional layer per year, and therefore allow the diets of bottlenose dolphins to be analyzed through different life stages.  Not only do such data provide a historical record of foraging ecology that can be accessed by sampling tissue from within GLGs, but comparisons of how natural disasters (e.g. Hurricane Katrina) impact bottlenose dolphin foraging ecology in the NCGOM can also be made.  Ontogenetic and stable isotope data will be used to develop a foraging ecology record prior to Hurricane Katrina and after.  
Carly Ginter Carly Ginter
M.S. Student
Research Interests: Carly is interested in the functional morphology and biomechanics of bumpy profiles.  As an undergraduate she worked with Dr. Frank Fish and Dr. Marshall to characterize the bumpy profile of seal whiskers, and with Dr. Fish she characterized the profile of odonocete dorsal fins.  Structures with bumpy profiles change the how fluid flows around these structures.  For pinniped whiskers it was been shown that their bumpy profiles impacts their sensory capabilities.  Carly's work on pinniped whiskers characterized the diversity of their profiles by fusing traditional morphometrics with outlined based geometric morphometrics.  She also investigated the flexural stiffness and material properties fo pinniped whiskers in a comparative context.
Emily Kane Emily Kane
M.S. Student
Our knowledge of the diversity and evolution of mammalian feeding is largely limited to terrestrial taxa; in general the biomechanics of marine mammal feeding has been overlooked. The majority of marine mammal feeding studies lack the detailed functional analyses commonly found in comparative feeding investigations of non-mammalian aquatic vertebrates. Other than suckling behavior, suction feeding is rare among terrestrial mammals. In contrast, suction feeding is considered to be a common mode of feeding among marine mammals. However, there are few detailed functional data to support or dispute these claims. The inclusion of marine mammal taxa in biomechanical studies of feeding is important to the larger goal of understanding the diversity and evolution of mammalian feeding. My research will focus on characterizing the kinematics of feeding on of beluga whale, pacific white-sided dolphin, and pilot whale suction feeding, which will add to data from previous studies of odontocete feeding conducted in the Marshall lab. I will also be performing a meta-analysis of both my research and previous research in the lab in order to begin to examine the relationships among taxa in an evolutionary context as well as the ecological implications of the associated feeding strategies. This will involve the integration of both kinematic motion analysis of digitally recorded feeding events and biomechanical analysis of pressure forces produced during the feeding event. In addition, pilot whales have recently been acknowledged as a target recovery species of longline bycatch in the Atlantic ocean. Modification of fishery gear help to reduce marine mammal bycatch, however an understanding of how pilot whales, and other odontocetes, feed is necessary before we can understand what type of modifications would be the best. My project will attempt to address this issue by utilizing pilot whales as one of my study species.
Rachel Neuenhoff Rachel Neuenhoff
M.S. Student
Age determination is an important tool in the study of mammalian populations, particularly populations such as marine mammals that exhibit long life spans and delayed maturity. Demographic models that investigate marine mammal populations require accurate representations of age structure. Surprisingly, few recent demographic data are available for bottlenose dolphin populations from the northern and western Gulf of Mexico. This is despite the fact that Tursiops truncatus is the most common cetacean in the northwest Gulf of Mexico, and the most commonly stranded species in Texas. Rachel will be collecting teeth from stranded bottlenose dolphins along the Texas coast. Teeth will be sectioned and stained for age analyses. The data will then be used to determine (1) population age structure, (2) growth from length-at-age stranding data, (3) mean length-at-birth, and (4) calving season. This work will be compared to a similar data set ranging from ~1980-1990 and will increase our knowledge of the population demographics and natural history of bottlenose dolphins off the coast of Texas over the twenty years. 
Brian Bloodworth Brian Bloodworth
M.S. Student
Research Interests: Cetaceans demonstrate a diversity of feeding adaptations that allow them to exploit their resources. However, to date, few data on the function of their feeding apparatus are known. My thesis research focuses on the comparative biomechanics of odontocete suction and non-suction feeding mechanisms. To investigate these feeding modes we use pygmy and dwarf sperm whales (kogiids) as models of odontocete suction feeders, and bottlenose dolphins as representatives of non-suction feeding odontocetes. The specific aims of the research are to determine the relative importance of suction versus biting for feeding in odontocetes, and investigate the adaptations of the hyolingual structure for suction feeding. These goals will be accomplished by integrating video footage of controlled feeding trials of both captive kogiids and bottlenose dolphins with biomechanical modeling of their hyolingual apparatus (tongue, hyoid, and associated structures). Kinematic profiles of suction and non-suction feeding odontocetes are compared and contrasted. Dissections of the hyolingual apparatus, vector analysis, measures of cross sectional area and fiber length will allow us to estimate potential maximal force production between presumed suction and non-suction feeding odontocetes. The integration of morphological and behavioral feeding data will provide new information on the function and diversity of odontocete feeding mechanisms and their adaptations to the aquatic environment.
Janelle Case Janelle Case
M.S. Student
Research interests: In order to understand the nutritional ecology of an organism, it is important to understand its ability to exploit these resources. One way to measure this is through behavioral performance studies of feeding capability. The main component of my research project is to measure the behavioral performances of juvenile red snapper feeding in the laboratory through controlled experimental feeding trials and subsequent analysis of feeding motions (motion analysis). Furthermore, feeding capability can also influence how well a species can compete with a congener or another ecologically similar species, which Janelle will demonstrate by comparing red snapper to other snapper species. The insight gained from these results can also be used towards conservation efforts. The last portion of her project entails a comparison between the feeding capabilities of wild caught versus hatchery raised red snapper which may provide essential information on the future survival of hatchery raised fish in the wild.
Alajandra Salazar Alejandra Salazar
M.S. Student
Research interests: Recent data reporting the large longline fishery bycatch of loggerhead and leatherback sea turtles is a serious concern for both managers and conservationists. Recent reports that changing the type of hook and bait can reduce sea turtle bycatch is intriguing, but does not address the direct mechanisms of how the hooking phenomenon actually occurs, nor its relationship with hook design and bait. The ability of loggerheads to excel in biting, and their associated feeding biomechanics (i.e., bite force capability, feeding behavior, and jaw-joint mechanics) is likely responsible for their vulnerability to fishery gear and in the hooking phenomenon. Ale will be investigating the behavioral performance and biomechanics of biting in loggerhead turtles at the Galveston NOAA Fisheries sea turtle facility. This one-of-a-kind facility provides an ideal situation to investigate bite biomechanics of loggerhead turtles from many size classes.
Heidi Amin Heidi Amin
TIO Undergraduate Fellow
Heidi Amin was a Texas Institute of Oceanography Undergraduate Fellow in the lab and investigated the sensory biology of bearded seals. She is a co-author with Dr. Marshall on a published article (LINK) regarding bearded seal vibrissae.
Jennifer Hill Jennifer Hill
Undergraduate Intern
Jennifer Hill was an undergraduate intern student studying the lateral line system in Atlantic stingrays using retrograde neuroanatomical tracing techniques.  She is completed her Ph.D. at Georgia Tech and is currently a postdoctoral scientist at Dauphin Island Sea Lab in Mobile, Alabama.
Mandi Moss Mandi Moss
B.S. Student
Pygmy and dwarf sperm whales (Kogia breviceps and K. sima), or kogiids, comprise the second largest group of stranded cetaceans along the Southeast U.S. coast. Kogiids that strand alive typically do not survive rehabilitation efforts and, historically, have succumbed to gastrointestinal (GI) complications within a month of captivity. Lethal GI complications result from gastric torsion and compaction related to indigestibility of food items outside the normal kogiid diet. Free-ranging kogiids specialize on deep-sea cephalopods, which are not commercially available. Instead, rehabilitators are forced to use common market squid and mackerel for rehabilitating kogiids. It is thought that kogiids possess a derived digestive anatomy and physiology. However, basic data regarding the structure and function of kogiid digestive tracts are unavailable. The objective of my Texas Institute of Oceanography Undergraduate Fellowship to conduct a systematic investigation of the anatomy and physiology of the kogiid GI tract to provide rehabilitation staff with a normal baseline of tract structure and function. This objective will be accomplished by: (1) characterizing the unusual gross anatomy of the kogiid GI tract and (2) characterizing the microanatomical and physiological function of each major GI tract segment using histocytochemical methods.  Mandi has completed a M.S. at Georgia Southern University and is currently working in the field of marine biology.
Zach Leman Zach Leman
Fabiola Rivera Fabiola Rivera