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An established partnership between ����ֱ�� University and the California Academy of Sciences (CAS) blends hands-on learning with scientific inquiry as students study the pathology of sea lion and sea otter skulls to better understand how environmental factors impact marine mammal health.  

This spring, a team of six students from Professor Doreen Gurrola’s Research Methodology course were granted unique access to the academy’s extensive scientific collection of sea lion and sea otter skulls, spending the past semester “reading” the skulls and collecting data. 

Next year, the students will draw on the data as they develop research papers and presentations examining how diet, environment, disease, and other threats have impacted marine mammals over time.

For Liana Lerona and Trinity Lopez, this work lays a strong foundation for careers in healthcare, offering a real-world application of anatomy and physiology. Liana aspires to become a dentist, while Trinity is working toward becoming a physician assistant.

CAS holds the world’s largest collection of southern sea otter and California sea lion skulls (about 3,000 skulls each). With such an extensive collection, students have the opportunity to ask questions and examine various aspects of the skulls. There are two research teams working on this project. The sea lion team examines the tooth abrasion and pathology. The sea otter team examines a unique discoloration of the teeth and bones that result from eating purple sea urchins.

With both projects, each skull is labeled by a catalog number, along with details of sex, collection date, and collection location. After selecting a skull to examine, the students enter this basic information into a database. Each project is looking for specific data. For the sea lions, students take four measurements of the skull — lateral total length, mandible length, medial width, and total height — before examining the teeth and documenting any abnormalities and pathologies. For the otters, the students are examining the pigment of the teeth and bones, along with the wear in teeth and abnormalities.  

The work requires precision, focus, and teamwork as the students study the pathology of each skull while also examining the teeth for signs of damage. Tooth abrasion in marine mammals is typically related to either feeding habits or behavior.

Liana, who is on track to complete her undergraduate degree in three years, first cycled through Gurrola’s lab during the Research Methodology course in the Department of Natural Sciences and Mathematics. This first-year course allows students to sample the research opportunities available at ����ֱ�� before applying to join a specific lab. 

When it came time to select a lab, working with professor Gurrola was Liana’s first choice. 

“When I heard we would be getting hands-on experience looking at the teeth of the skulls of marine mammals I was immediately interested because the correlation with my pre-dental focus works so well,” Liana says. 

At CAS, Liana is studying the dental pathology of sea lion skulls collected over many decades, examining abrasions, fractures, and other abnormalities for insight into the impact of diet and location. Liana also is examining a possible correlation between the length and height of a male seal’s sagittal crest — the bony bump on their heads that develops as the male seal matures — and tooth abrasion. She is excited about presenting her findings next year.

This focus on undergraduate research is what drew Liana, who attended James Logan High School in Union City, to study biology at ����ֱ��. She also applied to larger schools in the University of California system but eventually decided a smaller environment was a better fit in terms of access to research and faculty mentors. 

In addition to examining animal teeth at CAS, Liana has gained significant experience with human teeth through jobs and internships at dental practices both near her home in Union City and near the ����ֱ�� campus in San Rafael. 

Last fall, Liana interned for a San Rafael orthodontist, where she learned to take off braces and put on rubber bands. The experience left her enthusiastic about a career as an orthodontist. Already pursuing a minor in chemistry, working in dental offices inspired Liana to add a minor in business administration

“As a dentist, I will also be a small business owner,” she notes. “I had space in my schedule for another minor, so I decided that because I would own a business in the future, I should learn about running a business, from finances to marketing.”

“From being a student learning about biology and getting ready for the dental admissions test, to working for multiple dentists and doing hands-on work, I am grateful for every experience because I am just one step closer to reaching my goal,” she says.

For biology student Trinity, Gurrola’s engaging coursework and focused mentorship has been invaluable when it comes to studying complex issues related to anatomy and the human body. 

At CAS, Trinity is focusing on sea otter skulls. Echinochrome is the staining that occurs on their bones and teeth from eating primarily purple sea urchins. Trinity and her teammates are examining the variation of staining and whether there is a correlation between the pigment and the degree of tooth abrasion. This link between dental pathology and diet helps understand how environmental factors can influence diet. 

“We have already noticed that in certain populations from the Monterey Bay, there is more tooth abrasion, so now we are examining how that might relate to diet,” she says.

This spring, Trinity joined professor Gurrola’s field trip to the California Fish and Wildlife marine lab in Santa Cruz. The students witnessed necropsies of sea otters and heard from the researchers about the environmental factors impacting sea otter populations in the Monterey and Santa Cruz areas. 

“We got to see the anatomy of both a male and female and also examine a sea otter to determine how it died,” Trinity recalls. “It is a tedious but interesting process, as we had to focus on all the tiny details. We learned that even a small injury or wound could lead to infection and death.”

Trinity, who also is minoring in public health and psychology, eventually plans to enroll in a master’s program in Physician Assistant studies. Witnessing a necropsy provided more insight into human anatomy, a course Trinity also took with professor Gurrola. 

“Professor Gurrola kept pointing out the sea otter’s anatomy and then quizzing us on that organ’s role,” Trinity says. “It was really interesting to see and also discuss the similarities with the human body.” The lessons continued on the journey back to San Rafael, with Gurrola linking what the students had witnessed that day with what they were studying in class. 

“Human anatomy is a hard course, especially on the PA track, but Professor Gurrola works with us on memorization and breaking things down so that we really can understand how each organ and each system in the body works.”

Trinity, who graduated from Ponderosa High School in Placerville, heard about ����ֱ�� while searching for a school that would best prepare her for graduate school in Physician Assistant studies. 

“One of my counselors told me to look into ����ֱ�� because they have a good pre-PA track,” she recalls. 

“I was also looking at other schools, but when I visited ����ֱ��’s campus, I told my dad, ‘This is where I want to go. It feels like me,’” she recalls. “There was an instant connection, and I loved the fact that it was a little more diverse than other schools I had visited.”
 
Trinity will continue studying sea otters next semester as she continues to analyze data and prepare her research paper for presentation at a scholarly conference. She looks forward to presenting her research. 

Trinity credits a family member for ongoing inspiration to always do better. 

“When she was ill, my grandma said that I needed to study hard so one day I could take care of her,” Trinity recalls.

“She inspires me to work hard and pursue a career in medicine. My grandmother did not get to see me graduate and walk across the stage, but she remains my biggest motivation.”

All marine mammal stranding activities were conducted under authorization by the National Marine Fisheries Service through Stranding Agreements issued to the California Academy of Sciences and various Endangered Species Act permits.