The Rocks are Alive?

Many of us are intrigued by the large animals seen at Haystack Rock, which unfortunately leaves most people to step over, or even on, hundreds of very delicate creatures that cover almost every visible rock, barnacles!

Barnacles are crustaceans, related to crabs and shrimp. Although we mostly only see them motionless and stuck to rocks, they expend lots of energy to stay alive and live in a variety of places! 

The first stage of a barnacle’s life is a free swimming, one-eyed larva. It hatches from a fertilized egg as a result of sexual reproduction. The barnacles mission at this stage is to find a surface to live on for the rest of its life. This could be attached to a rock, a ship, a whale, a crab, or any other hard surface which will allow the animal to settle.

The method barnacles use to attach themselves to surfaces in a wet environment is rather intriguing. Researchers have recently (2014) discovered that this is a two-step process. The first substance that is secreted onto the surface is a lipid, displacing water from the chosen area. The next step is to secrete an adhesive compound in order to stick to the now water-free surface. When the barnacle finally attaches itself; it attaches its head to the surface it has chosen to stick to.

The next stage of the barnacles’ life involves a lot of feeding. For barnacles seen in intertidal zones, such as those seen at Haystack Rock, they will be seen in two different ways. Mostly, they are seen as motionless creatures. This is because when visiting the tide pools, the water is low and the barnacles are not submerged. This results in the barnacles closing in order to keep hydrated while the tide is out. They are then overlooked and damaged. Sometimes, if close enough to a large rock, people can hear a clicking sound coming from the rock; this is the barnacle circulating the water it has held inside. When visiting the tide pools many people jump around from rock to rock. While it may seem like a harmless little step, with so much exposure time and so many visitors during this exposure, these animals go through a tremendous amount of mortality.

If looked for closely, many barnacles can be found underwater feeding! To do this, barnacles use their feather-like foot to grab phytoplankton out of the water. There are two types of barnacles found at Haystack Rock, acorn barnacles and gooseneck barnacles. 

Acorn barnacles are the most common and don’t look like much more than a jagged rock.

Acorn Barnacles attached to California Mussels. 
Photo courtesy of Alanna Kieffer
Giant live acorn barnacle during negative low tide at Haystack
Photo courtesy of Alanna Kieffer

Gooseneck barnacles are a bit more noticeable than acorn barnacles due to their appearance. Most of the time gooseneck barnacles will be found along the top of the high tide zone and in very large clumps. Gooseneck barnacles get their name from having a long neck which is the part attached to the rock. The most visible part of the barnacle is on the end of the neck and is the part that tends to resemble a crustacean. This is the plated calcium shell. 
Piles of Gooseneck Barnacles in a crevice at Haystack Rock
Photo courtesy of Alanna Kieffer

When seen submerged in the water, as in the picture below, the calcium shell will open and the feather-like foot will come out and the barnacle will begin feeding. Macro and microscopic plankton, tiny organisms that cannot swim against the oceans current, will get trapped in this barnacles foot.

Feeding gooseneck barnacles
Photo courtesy of Alanna Kieffer 
Treat everything you ever encounter as a living animal until you find out otherwise, this will prevent any accidental and unnecessary damage. Remember that just because something is not constantly moving doesn't mean it is not a living creature. 

Go explore some tide pools with your new knowledge and see how many feeding barnacles you can find in one pool!


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