Lesson Plan

Seals of Glacier Bay 1: Flipper Feet

Harbor seals hauled out on a beach in Glacier Bay as the tide rises.
Harbor seals hauled out on a beach in Glacier Bay as the tide rises.


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Biodiversity, Biology: Animals, Marine Biology, Wildlife Biology
50 minutes
seals, harbor seals, Sea lion, pinniped, flippers, anatomy, marine biology, Glacier Bay National Park


Students begin this investigation by watching the seven-minute video,  Harbor Seals in Glacier Bay. Jamie Womble, a seal researcher at Glacier Bay, interacts with local students to answer questions about harbor seals and various ways to study them. Students compare their answers to the researcher questions and their reactions to the video. As researchers, students observe the similarities and differences between seals and sea lions and create a Venn Diagram to graph these features.


Focus QuestionsWhat characteristics distinguish seals from sea lions?
How can careful observation lead to a better understanding of an animal?
How are seals and sea lions similar and different?  


Our "Seals of Glacier Bay" curricula unit is divided into three lesson plans, each taking one class session to complete. They are part of our "Middle School Scientists" series that explore the fascinating research and resources of Glacier Bay National Park. Check back regularly for more lessons to be added.


Pinnipeds, also known as fin-footed mammals, are a group of carnivorous marine mammals that include three families of mammals: seals, sea lions, and walrus. Two species of pinnipeds live in Glacier Bay: harbor seals and Steller sea lions. Since they are both pinnipeds, these two animals have many similarities, but they also have key differences. With a little observation it is easy to distinguish between the two species.


Harbor seals are considered a "true seal" along with monk seals, leopard seals, and ribbon seals. True seals are found in marine and freshwater habitats in the Atlantic and Pacific regions. These seals have no external ear flaps (pinnae) and are sometimes called "earless seals." True seals have short necks and short flippers. Their short flippers cannot be pulled under their body, making land movement difficult. Though seals are graceful and agile under the water, they are awkward on land and usually move in an undulating, caterpillar-like manner. Underwater propulsion comes from moving their hind flippers in a back and forth motion and using their front flippers for steering. Males and females are generally similar in size and shape. Pups grow quickly and are usually weaned within several weeks.  


Steller sea lions, along with California sea lions and Northern fur seals, are known as "eared seals" for the presence of external ear pinnae. Sea lions have a more limited range than seals and are found only in marine swim underwater, sea lions flap their front flippers up and down, as if they were flying and use their hind flippers for steering. Sea lions are often vocal, emitting roars, barks, and growls. Adult sea lions are dimorphic: with male sea lions twice as big as a female with a thickened neck and a pronounced skull crest. A dominant male sea lion will form rookeries and mate with many female sea lions and defend his rookery from other males. Pups are born in the rookeries and many stay with their mothers for more than a year.  





In addition to the worksheets, the students will need pens or pencils and paper for drawing.


A photo gallery of pinniped images is available on the park website.


Park Connections

Visitors regularly spot harbor seals and Steller sea lions in the waters of Glacier Bay, but few visitors know how to differentiate between seals and sea lions. With this lesson, students can become experts in identifying these two fascinating creatures.


Take a look at other marine mammals that share the marine environment with pinnipeds, such as whales or otters. Have students expand the Venn diagram to include these other animals. What are some characteristics of marine mammals that enable them to survive in the marine environment?   

Additional Resources

Glacier Bay National Park

Pinniped Field Guides

Nature Journaling Lessons
http://www.smithsonianeducation.org/educators/lesson_plans/journals/index.html http://www.sierraclub.org/education/nature_journal.asp

Leslie, Clare Walker and Charles E. Roth. Keeping a Nature Journal: Discover a Whole New Way of Seeing the World Around You. Storey Publishing, 2003.  


pinnae, pinniped, Venn Diagram