It’s Phylum Friday in “Marine Biology,” an F&M course taught by Professor Peter Fields, and the class is learning about Porifera. More commonly known as sea sponges, these organisms are unique in their simplicity, which, Fields explains, should not be underestimated. Scientists believe that Porifera are among the earliest ancestors of modern animals. As the students observe photos of barrel, tube and glass sponges, they are looking at crucial moments in our evolution.
Fields incorporates this weekly tradition to illustrate the vastness of marine life, giving his students a sense of how much there is yet to discover and understand in our planet’s oceans.
“Phyla are the deepest divisions within the animal kingdom, and while only about six phyla have successfully colonized the land from their marine origins, there are more than three times that number that are only found in the ocean,” says Fields, The Dr. E. Paul & Frances H. Reiff Professor of Biology. “Phylum Friday allows me to share that diversity with students in the class, and hopefully help them develop an appreciation for how different body plans, some of which we would never see on land, allow animals to survive and thrive in the many habitats that are found in the ocean.”
The class turns to its continued examination of coral reefs, which have been suffering from weakened skeletal structures around the world. Coral are breaking frequently and growing at slower rates, Fields explains, because they do not have enough calcium carbonate in the water to maintain strong skeletons. It is a consequence of global climate change and the increased emissions of carbon dioxide into the atmosphere.
Ariel Eraso ’18, a biology major, asks the pressing question, “What happens if we continue to add so much carbon dioxide at this rate?”
The discussion centers on carbonic acid in the ocean, which is a product of carbon dioxide in the air. Carbonic acid has the potential to break down into bicarbonate and then carbonate, which coral needs, but those reactions are sensitive to pH. The decreasing pH level of the oceans is reducing the amount of carbonate available, harming coral and many other marine organisms with hard skeletons or shells, Fields says.
Although Franklin & Marshall’s campus is landlocked, Fields creates opportunities that put these discussions about global concerns into perspective. Earlier in the semester, the class ventured in stormy weather to Stone Harbor, N.J., an ideal setting for learning the basics of marine biology because it has three main habitats: beaches, salt marshes and mudflats.
There, the students searched for burrowing animals such as mole crabs and coquina clams. The rain meant that fewer animals were out and ready to be discovered, but the students recognized how their views of the beach environment changed after experiencing the class. They also did a plankton tow off the Stone Harbor Bridge and analyzed the plankton they collected at the local Wetlands Institute.
Topics on global issues—and explorations in marine environments—bridge the variety of student interests, majors and backgrounds in the class. Rachel Felder ’17, a double major in animal behavior and music, enrolled in the course because she grew up by the northeastern coasts of New Hampshire and Maine. During summers in college, Felder has worked as a naturalist at the Seacoast Science Center at Odiorne Point State Park in Rye, N.H.
“I think the most rewarding things in this class have been the connections I've made to my own experiences in marine biology,” Felder says. “Professor Fields does a wonderful job bringing disparate parts of a lecture back to a bigger picture. I look forward to seeing how a new part of the ocean can relate to the part that I know so well, and yet how different and diverse the organisms can be.”
Peter Fields, The Dr. E. Paul & Frances H. Reiff Professor of Biology
FALL 2016 SEMESTER
Wednesday & Friday, 11 a.m. – 12:20 p.m.
- Regulation of Keystone Predation by Small Changes in Ocean Temperature (Eric Sanford, Science)
- Coastal Eutrophication as a Driver of Salt Marsh Loss (Deegan
- et al., Nature)