They live in the intertidal zone, that narrow strand between high and low tides.
If you’ve ever rubbed up against them you won’t have forgotten. They’ll peel the skin right off you. A swimmer’s nightmare. A painful jolt to a hiker who stumbles into them.
Cousins to crabs and lobsters barnacles are curious creatures.
Free-living in the ocean at birth, little barnies attach themselves to rocks and logs and crab shells. Cement themselves to the surface and never move again.
They thrive underwater. Their legs, morphed into frilly appendages, sweep the water for food, drawing particles down into the opening of their self-made home.
Plates — kind of like folding doors — surround the opening. When the tide goes out they clamp shut to keep out predators and protect the barnacle from drying out.
Acorn barnacles are common on the shore I visited. Not sure why the word acorn was chosen. Someone must know.
Thatched barnacles — a type of acorn barnacle — have vertical ribs like skinny fingers on the walls of their homes. Sort of like thatching on a cottage.
Check out the photos. You’ll see the difference.