August is beach month, so if you’re heading for the ocean here’s something to look for while you’re there.

Stop by a pier, check out a jetty or gaze into rocky tidal pools to find submerged barnacles.

When you find them watch carefully and you’ll see how they feed.  From the “mouth” at the top of the shell they extend their cirri to comb the water for food.

Click on the screenshot above to watch a quick movie of Semibalanus balanoides barnacles feeding in Greenland’s clear seawater.  This species is the only intertidal barnacle you’ll find on North America’s north-east coast.  It occurs as far south as Cape Hatteras.

Check out the barnacles.  They have “arms” and they’re waving.

(barnacles photo by Kate St. John)