The 'Glades

I could not believe that I was seeing mangroves!  I had only seen these strangely adapted trees on TV, but now I was seeing whole islands of them was we cruised by on a tour boat through a small section of Big Cypress National Preserve.  Our main goal was to look for manatees and dolphins, but my main goal was just to experience the Everglades (and to do a little bird watching).

The reason for this weekend vacation was to visit my sister who works for North Carolina Outward Bound, which is an organization that offers outdoor adventure courses to the public.  Basically, she goes out for up to 28 days at a time with clients and lives on flotilla of canoes.  When she is not "on course" she lives "on base," which is a small community of quaint beach-house like buildings only accessible by canoe.

Now you may be wondering why North Carolina Outward Bound has a base camp in South Florida, but just like many migratory birds, the North Carolina Outward Bound Company migrates south for the winter and returns to North Carolina to run programs in the summer. Not a bad gig.  As my final semester in graduate school gears up, I would be lying if I said I was not just a little bit jealous.

Back on the tour boat, we pass by one of these island of mangroves close enough to see that the roots are covered with thousands of tiny shells.  These living creatures are a testament to the key role mangroves play in the Everglades environment. For without the mangroves, these creatures would have no place to live.  What I am looking at are mangrove barnacles, tiny creatures in the phylum Arthropoda, the same phylum as all the insects.  Although this is not what many tourists have come to see, I find myself amazed at the adaptive ability of these tiny creatures.

When they are born, barnacle larvae are planktonic, meaning they are free-floating, drifting with the tides.  As they become mature, they cement their heads to a suitable surface, like mangrove roots, and begin encasing themselves in a calcium carbonate shell.  Location is imperative to the survival of an individual barnacle!  If the barnacle decides to cement his head at too high an altitude where the high tide only sometimes reaches, then she will dry up and die.  (Barnacles need to breath oxygen dissolved in water, just like fish.)   But, if she decides to glue her head to a place that is constantly submerged, then she has to compete with other creatures trying to make a living in shallow water, not to mention increased exposure to predators.  Luckily, barnacles have adapted to live in what is known as the intertidal zone, or space between high tide and low tide.

But how can these little creatures who stay in one spot their entire adult lives be able to spend roughly have their day out of water when they require water to breathe?  The answer lies in their shell.  Not only is their shell built in such a way as to deflect wave energy as the tides move up and down, but also, their shell acts as water storage for when they exposed to air.  As the water retreats during low tide, barnacles close up their shell and hold enough water in there to breathe until the tide returns.  Thus, these little guys are able to persist in an environment that is underwater have the day, and exposed to the atmosphere half the day. In this constantly changing environment, most creatures, including us humans, would perish.

Plus, since their heads are cemented to mangrove roots, they have to reach out of their shells and grab food with their legs.  And if you are grabbing food with you legs, and your head is stuck to a mangrove root, where do you put the food you just grabbed?  That's right, in your butt!  Ha!

Oh and check out this YouTube video for the more intimate aspects of barnacle natural history.

That's probably more than anyone wants to know about barnacles.  Barnacles are cool.

The mutualism between the barnacle and the mangrove is just one of many that exists in the 'Glades, and although barnacles are by no mean endangered, the habitat they live in is. On top of the multitudes of invasive exotic plants and animals that are encroaching, the Everglades are shrinking, and this is in large part to land-use changes that have resulted in decreased flow of freshwater from the surrounding area.  In fact, the Everglades is less that 1/3 it's original size, and a plan to increase water flow to the Evergaldes has been put on hold.

Luckily, there is an organized group of concerned citizens advocating  the Comprehensive Everglades Restoration Program in the face of such setback.  On their website you can view the plan, and they have a bunch of ways for you to get involved.  So get out there and save the barnacles! (and the millions of other species that call the Everglades their home)

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