Mole Crab Research

Good scientific research is based around data. Whether it be data collection in the field or analysis in the lab,  data is the driving factor to finding results and confirming or rejecting a hypothesis.  Bay’s Marine Biology class spent a morning this term working as citizen scientists in the National Marine Sanctuaries Limpets (long-term monitoring program and experiential training for students) program to help collect data for their ongoing research around the health of the San Francisco Bay. The program has sandy beach and rocky beach monitoring sites along the entire coast of California.  High school and college students monitor these sites and the data collected is added to the National Marine Sanctuaries’ national database.

Bay students participated in the mole crab monitoring program.  Mole crabs are considered an indicator species because they are a key connection between the plankton food sources and larger organisms that live in the ocean and on land. The health of this population indicates the health of other less visible groups.  For this project, students were trained in class on the monitoring methods, and how to identify male, female and recruits (juvenile) mole crabs.  They sampled a 10-meter vertical transect and recorded the number of crabs they found.

For the students in this class, teacher Nettie Kelly developed several goals for this trip: 1) to learn a field monitoring technique, 2) to learn about arthropods, and in particular the life of the mole crab as an exemplar of this group, 3) to contribute to a large dataset of long-term data about a local coastal area and 4) to access and analyze the data in that dataset to draw conclusions about the health of Crissy Field.

In addition to the time students spent on the beach, students also worked with a random sample of large mole crabs to check for parasites in the lab.  As the mole crab acts an intermediate host for a marine parasite, the parasite load in the crabs can indicate the level of impact of the parasite on animals higher up the food chain.  The class dissected the crabs, counted parasites and added this data to the national database. This type of experiential learning helps students engage in authentic research, thereby applying their learning to a real-world need.

Take a look below at some of the photos of the students’ work at Crissy Field as they collected samples and back in the lab as they dissected and analyzed the mole crabs.  

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