Why is The Shelling So Darn Good?

Sanibel and Captiva are shaped like a boomerang and have an east-west orientation rather than the usual north-south barrier island positioning. Sanibel sticks out in the gulf and acts like a giant scoop for shells moved to the North by coastal winds and currents from the South. Ocean’s Reach is desirably located at the elbow of the boomerang which offers a treasure trove of shelling possibilities for Ocean’s Reach guests.

Shallow seas extend well into the gulf. Miles offshore the water is less than 40 feet deep. By comparison, in the Florida Keys, miles offshore, the depth of the water could be as much as 300 to 800 feet. The gradual slope of the Gulf bottom acts like a ramp that allows large numbers of shells to make it to the beach, especially when propelled by storms from the northwest. These storms commonly occur in December and January when a cold front passes through Florida.

Far offshore, beds of live shells build up for extended periods of time. As strong, sustained winds produce underwater currents; these shells are washed up on the beaches. More than 300 species of shells can be found in the shallow water surrounding the islands.

Shells are much more prevalent on Florida’s West Coast beaches than on the East Coast. There are steep drop-offs on the East Coast. This creates a wall-like barrier that traps shells and the abrupt change in the depth of the water creates pounding surf, damaging shells before they can reach the shoreline.

Beaches can be thought of as the restless battlegrounds between ocean and land. The shifting sands are controlled by winds, tides, currents, and the angle of beach slope. The beach is a graveyard for offshore species up-rooted by stormy seas.

Live shelled animals can be thrown onto the beach by storms but can’t survive for long on dry sand and only a few species, like coquinas, live on wet sand. The rest live under water and wash ashore after they die. Generally, shells found on the beach are the hard external remains of these sea creatures.

The broad beaches on the Gulf of Mexico are pounded by strong waves, while on the lagoon and bay side of barrier islands the quiet beaches are narrow and mixed with fine mud. Beaches constantly are being changed in size and nature by the moods of the seas.

In general, winter storms bring shells into shore and summer calms take them away.

There are billions of living shells offshore along Florida’s 80-mile wide continental shelf that extends for thousands of miles from Alabama to the Lower Florida Keys. A small fraction of them reach our shores, particularly after storms. Miles off the coast of Sanibel the water is less than 40 feet deep. In comparison, in the Florida Keys the depth could be as much as 300 – 800 feet. The gradual slope of the Gulf bottom off Sanibel’s coast acts like a ramp and allows large numbers of shells to roll onto the beach. The gentle slope also assures that many shells arrive in undamaged condition.

Sanibel juts out into the Gulf of Mexico in a westerly direction instead of hugging the coast line in a north/south direction like most barrier islands. When cold winter winds from the north or northwest blow across the island they push the surface waters away from the land. Bottom currents are set up in the direction of the land to replace the surface waters. This uproots live shells and brings them ashore, often in vast numbers. These storms are common in December and January when cold fronts pass through the state.

During times of southerly breezes, especially in the summer and early fall, gentle surface currents pile up against the island. The extra water retreats in the form of bottom currents, taking beach shells and sand back out to sea. On rare occasions, violent summer thunderstorms from the north reverse this cycle.

Most live shells that wash up on shore are destined to end up as dead specimens. In time, they erode and crumble up into beach sand.

You can see more living mollusks at low tide and at night. Check the tide schedule with the Shell Museum, local newspapers, or the Internet and be sure to obey the local shell laws.