As you walk around the beaches of Florida there is a lot to see. But what you may not realize is that a very tiny creature that is beneath your feet plays an important role in the ecosystem of the beach. You may not always see them if you are not paying attention or looking for them. Introducing.... the conquina clam shell!
The coquina clam shells are very small, usually around 1/2" in length, come in a variety of colors, and can be found in abundance (if you are paying attention). The coquina clam is so important to the beach ecosystem because it is a filter feeder, thus cleaning the clarifying the water as it gets its nutrients. The coquina clam is a bivalve, meaning that it has two half shells that come together, is a mullusk, and is part of the donax genus.
If you look closely you will be able to see on some of the coquina shells that they have two small siphon tubes. One tube is used to bring oxygen and nutrients (e.g., phytoplankton, organic matter, bacteria) into the coquina clam, while the other is used for elimination. Some coquina have "hydroids," which look like tiny bushes that are attached to them. You can often see the hydroids stickig up out of the sand, even when you cannot see the rest of the coquina. When you just sit and watch the coquina for a while you notice that the tide uncovers them, but as the tide receeds they quickly burrow right back into the sand.
We've been on the beach on days where we don't see many coquina at all, and days when there are thousands along the beach. If you have kids, be sure to show them this delicate, but important marine animal. And please, teach them to respect them (live and let live). I've seen kids on the beach killing them for fun, picking them apart, etc.
Coquina was used in history as a building material. You can read more about that here, where some structures in St. Augustine were built with coquina.
Here are two videos that my daughter and I took this week of coquina on Daytona Beach. She was really proud to be my assistant in shooting this video and wanted me to make sure I mentioned it in the blog post. Check out the videos to see how the coquina burrow themselves back into sand once tides recede.