Tuesday, February 12, 2008
I was walking near the pier on Ocean Isle Beach, NC and noticed all the barnacles on the pier pilings.
Surprise, surprise, these are crustaceans! The crustaceans you are used to seeing, lobsters, shrimp, and crabs are in the subclass Malacostraca, but barnacles are in the subclass Cirripedia. They have fewer appendages and segments and their organs are rearranged. In fact, the barnacles that are attached to surfaces are thought to be attached by their heads!
Most barnacles are hermaphroditic and they cross fertilize their eggs. They drift though the water and find a suitable place to attach. As they mature, their mantle secretes an external shell. They have plates that interlock by overlapping and in the center they have two sets of plates that act as a door. When in the water, the barnacle opens and closes it’s doors and it extends it’s cirri (feathery legs) and catches any plankton or detritus in the water. They are filter feeders. After they mature,they put out a chemical which attracts other barnacles. That’s why you will find them in clusters. Most live attached to firm surfaces like pilings (where these pictures were taken), rocks, oysters , boat bottoms or even turtles, whales and crabs .Early naturalists misclassified barnacles as mollusks
because of the outer shell-like structure.
This is a Striped Barnacle Balanus crenatus.
It’s interesting because in the North, it is white with grey stripes and south of Cape Hatteras, it’s white with purple stripes.
It is very similar to the Ivory Barnacle Balanus eburneus which is smooth and white. Seen below.
Someone sent me a video on bio-luminescence and camouflage in sea creatures and I thought it was very interesting.
Click on the link below to watch.