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Finding live barnacles, mussels, clams

Find shelled animals living on rocks at the beach and find out how they eat.
Science content (2016 curriculum): 
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Science topic (2005 curriculum connection): 
Life Science: Characteristics of Living Things (grade K)
Life Science: Needs of Living Things (grade 1)
Life Science: Animal Growth and Changes (grade 2)
Lessons activity is in: 
  • Rocky beach with live shelled animals e.g. barnacles, mussels, clams
  • Optional: clam or mussel, fresh but dead, opened up to see the internal organs

Ask students to find barnacles on a rocky beach. Point out the young and old barnacles, and the scar where a barnacle used to be.
Live barnacles can be gently touched to make them shut their shells tight.
Watch barnacles feeding:
Find some live barnacles on a loose rock that are not covered by water. Move the whole rock into a tub of sea water. Watch and wait, and they will first release a bubble of air, then gradually open up and start feeding. You can collect a rock of barnacles and some ocean water and bring into the classroom - once submerged they will start feeding.

Find live mussels stuck to rocks and/or live clams buried in the sand.
Optional: dissect a clam or mussel.
Review how clams and mussels feed.

Summarize that all these animals, and many others, are filter feeders (more information at

Review what the shells of all these animals are for (protection against predators), and ask how predators might open the shells. Ask if students have seen seagulls and crows dropping clams on the rocks to open them.


Barnacles will feed for a while in a classroom. In warmer water they will feed faster (compare rates in cooler and warmer water). They can be collected and kept dry for 10-12hrs (optional in a cooler) before immersing in ocean water to show feeding.

Grades tested: 
Gr K
Gr 1
Gr 2
Gr 3
Gr 4
Gr 5
Christy Wong
Diane Merchant
Julie Kawaguchi
Kecia Boecking
Teaching site: 
General Gordon Elementary Science Club
ingridscience afterschool
McBride Elementary
Weir Elementary
Activity originally developed and delivered: 

Scientist in Residence Program, Vancouver School District with teachers Ms. Kawaguchi and Ms. Merchant.
This activity is part of the Scientist in Residence lesson plan