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Below is the active list of scheduled boat dive trips. Be sure to contact the charter directly for confirmation, rates, booking and other info.
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Author |
: Bruce Watkins |
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Date |
: January 23, 2009 |
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The last time you swam along a rocky wall or pinnacle you may have noticed the rock grinning back at you with a vibrant red or green “smile.” Like a Cheshire cat, you see the smile—then it disappears. Unless you are very attentive, the smiling animal is so well camouflaged that you may never be able to locate it again. These are not mythical animals, but the lips of a sedentary invertebrate—the rock scallop.
Rock scallops were given the scientific name Crassedoma giganteum, but were previously called, Hinnites giganteus before the classification was redone some years ago. They are mollusks, non-segmented animals with (usually) a hard shell. The phylum Mollusca is the largest and most diverse phylum of animals next to arthropods, and comprises nearly 100,000 species. Mollusks can be found in nearly every ecosystem on earth, from mountains to grassy plains, lakes, rivers, and in all seas and oceans. Scallops are classified into the Class Bivalvia, having two shells, and the Subclass Pteriomorpha, the oysters and mussels. They are further classified in the Order Ostreoida, the true oysters, and then into the Family Pectinidae, the scallops. In total there are more than 30 genera and around 350 species of scallop. For reference clams are found in Subclass Heterodonta. Scallops; therefore, are more closely related to oysters and muscles than clams.
Rock Scallops may be found from British Colombia to Baja. They are common on rocky exposed outer coasts, and offshore pinnacles from low intertidal to over 150 feet and thrive on reefs that are subjected to strong currents. Scallops are filter feeders and rely on these currents to bring plankton to them. Rock scallops are almost always found out of direct sunlight and normally have a covering of marine growth that makes them nearly indistinguishable in with the surrounding rock.
All scallops are broadcast spawners—they release eggs and sperm into the water at the same time. In Central California rock scallops spawn in April. There are boy scallops and girl scallops—the boys have white gonads while the girls are red. Interestingly, they do not spend their entire lives as one sex, and may change back and forth several times in a lifetime. However, they exhibit the characteristics of only one sex at a time. The scallop larva are planktonic and drift at the mercy of the currents. As they grow larger they begin to lay down a hard shell and sink to the bottom, hopefully in a suitable habitat. At this time in their life, rock scallops look much like bay scallops with the common "Shell Oil Company" logo shape. They move around by jet propulsion by flapping their shells together.
Once they grow to about an inch or so in diameter, they then flap their way up into a rocky nook and begin to cement one shell to the rock. They accomplish this by extending their mantle and laying down shell material between their shell and the surrounding rock. When this material hardens they are stuck for good. Sedentary scallops grow very slowly and may take 25 years to reach 5 to 10 inches.
Scallops have many small eyes, each complete with a lens, cornea, and retina. The eyes are very sensitive to changes in light levels and they can detect a diver from many feet away. Scallops will then rapidly close and this movement is often what draws your attention to the scallop. They are also sensitive to vibration, so divers that swim off the reef will see more "smiles." They may also be recognized by their bright red or green mantle. It is not known what causes this color difference.
Rock scallops are also one of the most sought after shellfish by Californian divers. Divers who learn to spot and harvest these tasty morsels will be rewarded. In general it is risky to eat the entire animal. As planktonic feeders they may concentrate paralytic shellfish toxins in their liver and gonads. This usually occurs during “red tides” in late spring/summer. Divers should only eat the large abductor muscle, since it relatively free of toxins. Anyway, that is the best part.
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