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Find barnacles on a beach, or look at ones brought into the classroom. Watch them filter feed.
Science content (2016 curriculum): 
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Biology: Food Webs, Ecosystems, Biomes (3, 4)
  • rocks with barnacles on them, preferably that have been out of water for a while (so they are hungry!)
  • clear jars to hold each rock
  • containers of sea water

If this activity is to be conducted in a classroom, collect small rocks with barnacles attached, and store in the fridge overnight out of water. Also collect two containers of sea water, one kept in the fridge, one at room temperature. Return the barnacles to the same beach after the experiment.

At a beach, ask students to find barnacles themselves. 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:
Transfer barnacles on a small rock to a jar of sea water.
Watch and wait. The barnacles will first release a bubble of air, then gradually open up and start to feed.
Their head is down attached to the rock. Their legs (called "cirri" in a barnacle) point upwards and beat back and forth to catch tiny particles of food in the water.
Barnacles at the beach start filter feeding when the tide comes in, and close up when the tide goes out.

Optional: compare beat rates of barnacles at different temperatures. Students first watched barnacles in sea water from the fridge and sea water at room temperature and qualitatively observed the cooler barnacles beating more slowly.
Then students counted the beats per minute for several barnacles in each temperature. Class data added to one graph. (Though our data was not too striking, as the cool water had warmed up quite a bit before data was collected - the water temperatures were now 11 and 15 centigrade. See photo of graph. Different barnacles also beat at different rates, so need a large sample size.)


Tide low enough to find barnacles: 11ft tide below Tatlow Park.
Sea water is about 10 degrees C.

Grades taught: 
Gr K
Gr 1
Gr 2
Gr 3
Gr 4
Gr 5
Gr 6
Christy Wong
Diane Macqueen
Diane Merchant
Elaine Ong
Julie Kawaguchi
Kecia Boecking
Kevin Dwyer
Pascal Spino
Teaching site: 
Britannia Elementary
Fraser Elementary
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