Sunday, July 11, 2010

It's a rock, it's a plant, it's a BARNACLE!

One of the most frequent questions I got in my first week at Camp Harbor View was: what are those yellowish things on the rocks? Guesses ranged from "baby rocks" to "dried fungus" to the "real" answer: "they're barnacles-DUH!!". Many kids were incredulous to find out that the gnarly little calcareous (made of calcium carbonate, a chalky substance found in some rocks) dots studding the rocky coastline and covering dock posts and moorings actually contained living animals! They wanted to know more, and I was surprised and excited to find in the campers were just an enthralled by the natural history of the barnacle as I am:) Barnacles start their life as planktonic larvae, teeny tiny babies floating in the ocean. When they are ready, they use special chemical sensors to find a good place to settle on -- this is important, because once, they settle down, they're stuck there for life! The baby barnacle attaches by literally cementing its head to the rock with a special glue. Finally, they build the calcareous armor we recognize as white dots on rocks and moorings to protect themselves from predators and keep their small bodies moist when the water-level sinks and leaves them exposed on dry rocks. At high tide, they open up to feed using a fancy structure called "cirri" that look like little fans to scoop plankton out of the water. Curious what they look like when feeding? Check out this video from the Marine Ecology Center to see what they do when we can't see them:


1 comment:

Bruce Berman said...

Nice post. Now tell me about those pesky tunicates...