The intertidal area is where the land submerges under the ocean and the tidal zones begin. This complex marine ecosystem is found along coastlines worldwide with general similarities expressed by local diversity. It is a fascinating place to explore and appreciate, especially when accompanied by an understanding of the ecology that holds it together.
Imagine being plunged into a washing machine, filled with rocks and icy water, and setting it on the heavy wash cycle. After a few hours in these conditions, you are transferred to an asphalt surface during a heat wave. Repeat every 12 hours and 25 minutes, or so. For those remarkable organisms that call the intertidal zone home, this is similar to what they experience on a daily basis.
Along the coast of California, the intertidal zone spans a height of about 2.7 meters (9 feet), which is the extent between the highest high and the lowest low tide. Just 2.7 vertical meters! And yet this predictably precarious margin of damp rocks and turbulent surf is the only place on Earth that many organisms call home.
The boundary between surf and turf is a rich landscape, offering many rewards to those who are hearty enough to live there, but life here is not easy. In a matter of hours, a parched and baking landscape shifts to a seascape where frigid and unforgiving waves take control.
So, what does it take to live in such a wild location? It seems that most organisms interested in taking up residence take one of two approaches: be tough or be flexible.
The Tough Guys
When faced with battering surf, threats of dehydration and countless creatures looking for an easy lunch, a common adaptation in the intertidal zone is to be tough and don some armor. Many creatures take measures to protect their bodies by having a sturdy protective boundary in the form of an exoskeleton or shell: crabs, barnacles, urchins, snails, limpets, chitons and mussels.
Among the armor clad, one of the most steadfast is the mussel. These bivalves are currently being studied by medical researchers who are curious to know how they’re able to remain so firmly attached to the rocks, despite incredible pressure from wave action. It turns out that the mussels are always reinforcing their connection to the rock they call home. As the tide comes in and they’re covered by water the mussel will extend its foot and mend its connection to the rock by producing incredibly powerful strands of protein that appear to the casual tidepooler as hairs. The possibility of studying this remarkable adhesive power and using it for medical purposes is really quite exciting.