Something about Seashells

At a soiree some years ago, I had the pleasure of meeting R. Tucker Abbott, recently deceased, who is known to most of you as the author of a series of beautifully illustrated books about seashells. After the meeting we repaired to his hotel where I picked his brain about sea shells for about 2 ½ hours, while all the ladies except Sue Fish talked woman talk. Sue and I queried him about everything we always wanted to know about molluscs, but didnt have anyone to ask. Let me regale you with a few of the tidbits we learned.

Have you ever heard that the Chinese manufacture valuable wentletrap shells out of rice flour, so skillfully that most people, even conchologists (shell specialists), cannot tell by looking at them that they are synthetic! Well Tucker says it aint so. Just a good story that crops up every so often.

And how about the shells that coil clockwise in the Northern Hemisphere and counterclockwise south of the Equator? Joseph Conrad (I believe) says so in one of his books, and it is widely believed. Again, it isnt so!

While Coriolis Force operates on all moving things, including seashells as they grow, the term in the Coriolis Equation for velocity is so small for growing shells, that natural forces and genetic determinants make them coil the way their genes say. There are some clockwise coiling shells and some that coil counterclockwise, but few that coil both ways and none that he knows of that are directed by the location north or south of the Equator.

Rarely a shell that should normally coil in one direction will be discovered coiling in the wrong direction. Such shells are extremely valuable to a collector, but it will do no good to take larval shells to Australia to get opposite coiling. It doesnt work.

Tucker also told us the name of the most valuable shell in the world, but I've forgoten it. I'd always thought it was the Glory of the Seas Cone shell (Conus gloriamaris), but it isn't, at least not any more. Years ago, only a very few of these shells were known and each was worth a small fortune. Then more and more showed up and the price dropped. Natives of the Indo-Pacific region, who fish for shells for the souvenir and collectors markets, found that they could catch the Glory of the Seas Cone by spreading a fine mesh net on the bottom with bait in the center. The snails crawl up on the net, get their foot caught in the mesh and are captured. By the way, foot is the proper term for the part of a snail that carries the shell along! Thats why the scientific name pelecypod, for hatchet foot!

I asked him if our Atlantic cone shells were poisonous. I've caught Crown Cones in Florida and handled them very carefully. He said that all cone shells are poisonous; some much more than others. There are several in the Pacific that are so deadly that they can kill a strong man!! Fortunately our Atlantic cones are not so bad.

Several cases of stings by Crown Cones and other Atlantic cones have been described. They apparently feel like a bad bee sting. The stinger is one of the many possible modification of the snails foot. Some snails use a radula (file like part of the foot) to rasp holes in other snail shells, or in sea biscuits, so they can eat the insides. Others modify the radula into a harpoon like stinger. Ah, the wonders of my ocean!

Interestingly enough, long ago I spent some time on Johnson Island, in the north central Pacific. Our main recreations were diving, and watching the MATS planes that landed on our airstrip, to get a glimpse of a real live female stewardess. One day a boat pulled up to our dock as we were washing our dive gear, and a young man held up a cone shell about 6 inches long. Look at this beauty, he said. I looked and immediately knocked it from his hand and into the water. Good god, man, I said, dont you know that cone shells may be deadly? Read R. Tucker Abbotts books about shells sometime! He was livid, and said Tucker Abbott is my uncle. But he had not read the books and did not know the cones were poisonous. When I dove down and carefully retrieved the shell, it was dead and there was nobody home. He hadnt known it, tho, and could have died for his ignorance as is reported for a football player from Hawaii, who lasted almost two hours after being stung by a beautiful cone.

How does a spiny oyster (Spondylus americanus) build its long curved spines? And for that matter, the same question might be asked for many other similarly ornamented shells. Well, Tucker says there are shell secreting cells in the mantle of the spiny oyster (which is really a kind of scallop). When the animal decides to enlarge its home, these cells deposit a layer of calcium carbonate around the edge of the shell and make it bigger. Periodically it sticks a finger of mantle and shell secreting cells up into the water for two or three inches and starts to make new shell around this fleshy protuberance. As it deposits carbonate, the fleshy part slowly withdraws into the shell leaving a long beautiful spine behind.

I was glad to know this because I've wondered about it ever since I found my first spiny oyster in about 120 feet of water off SE Florida. He also said there is only one species of Spondylus locally. When it grows on a reef, the spines are usually poorly developed and the shell is more massive. Perhaps reef critters bump the fleshy spikes and they withdraw without completing the spines. On the sand and rubble flats in deeper water, the spinys grow long beautiful spines that make them worth $25 or more to the collectors and touristas.

Very often one find the spiny oysters growing on a small fragment of shell or coral in the deep water. They commonly are coated with an encrusting sponge which is quite distinctive. I look for the sponges to find the spinys, but only take one or two a year, so as not to rape the reef. Tucker tells of the Venus Cone, which has long thin spines situated in such a way as to form a cage around the foot. As the cone wanders along the bottom, the shell is held high by the extended foot, but if attacked, lowers the shell quickly so that the cage protects the vulnerable soft foot. Id often wondered what purpose such extreme ornamentation served.

Tucker did not say this, but I suspect the long spines on the spiny oyster and the Venus Cone, for example, may deter another mollusc, the octopus, from eating them. We learned a great deal more from Tucker Abbott, but there is a limit to what you can absorb in one sitting, so Ill save more stories for another time, or, better yet, get one of the R. Tucker Abbott shell books and learn for yourselves.

Anchoring a boat seems to be a problem for a good many people, considering the number of anchors we pick up on the reef, and the people we pick up, before we chase down their drifting boats. Accordingly, here are some hard won tips for you relatively new boaters and divers, and even for some old boaters who have been lucky!

First there are the parts of an anchor. The long straight portion, ending in some kind of ring for attachment, is the shank. On the end opposite from the point of attachment of the anchor line, which is properly called the anchor rode, are the flukes. They are the portions of the anchor which dig into or hook on the bottom to keep the boat from drifting. Typically they will be elongate triangles, but on old anchors, may be heart shaped. On some anchors, but not as much today as in the 19th Century and before, there is also a bar across the attachment end of the shank, the function of which is to keep one or both of the flukes pointed at the bottom so that they dig in.

The anchor works on the principle that the shank will be nearly parallel with the bottom, placing the flukes so that they dig in. Here lies the whole problem with most peoples anchoring technique. If the shank rises up to 45 or more degrees from the bottom, the flukes cannot get a good bite and the anchor pulls out, allowing the boat to drift away, or to drag, plowing the bottom up, but resulting in a dive on a spot not of your choosing, and often out in the sand. To hold the shank low to the bottom, two main techniques are used, often togeather.

The first is to add a length of chain between the shank and the anchor rode. The length and size of this chain is chosen to provide adequate weight on the shank to hold it down, and at the same time to keep the part of the anchor rode which is closest to the bottom from sawing thru on a coral head or rock ledge, a situation which you can avoid by anchoring in sand whenever possible. Do not succumb to the temptation to use small chain and only a short length. Better a little work weighing anchor than no boat when you come to the surface after a dive.

The second thing is to provide so much anchor rode that the catenary between the chain and the boat is gentle, and the pull on the chain and anchor is nearly parallel to the bottom. This means, not 110 feet of rode in 100 feet of water, but 250 to 300 feet-REALLY!! For anchoring where the boat must ride out rough conditions, untended, the U S Coast Guard recommends 500 feet of anchor rode. As divers, we sometimes set our anchors under a ledge of rock, since we dont often dive on bare sand. In the latter instance we make sure the anchor is digging in well. For a fisherman or surface boater, anchoring becomes important when the weather deteriorates and there is danger of either being blown onto the beach, or out to sea.

A prime example of the result of too short scope was a recent attempt to dive the REBEL, a deep wreck off Pompano Beach. The first two attempts, with a good anchor and 8 feet of heavy chain, resulted in our dragging across the bottom at a great rate. For our third attempt, we added another hundred feet of anchor rode, and got ready to go over immediately after dropping the anchor, before it had time to drag very far. It turned out that the flukes dug in very well with the extra rode and we had a nice dive. We tried the TRIO BRAVO in somewhat deeper water, and dragged badly, never finding the wreck.

Many boats that I have been on do not have additional anchor rode aboard. Many, indeed, have far too little to start with. Ive pulled in boats that couldnt anchor in 30 feet of water. Their anchor rode was about 30 feet long, and all their dock lines had been left at their berth. One man, whose life was saved by a Dutch tanker, far out in the Gulf Stream, at night, in the winter, lost an engine drifting over the Third Reef off S.E. Florida, and by the time he realized that he couldnt get started, he was in 150 or so feet of water. He, too, had too little anchor rode to do the job. It almost cost him his life.

On one occasion, I watched a sailboat trying to anchor in about twenty feet of water. They tried and tried just about 100 yards ahead of where we were diving. They were clearly frustrated. I finally yelled at them and found out that their anchor would not hold. When we pulled up close it was apparent why. The rode was straight up and down. The anchor was pounding the reef to pieces but in no way could it get a bite and hold the boat. They were offended when we suggested letting out more line!

Let me relate one very valuable trick which has twice saved a boat that I've been on, in very rough seas, in the surf zone, with waves breaking all around us. When we lost an engine, we threw over an anchor with all the scope we dared, until the breakers, eight or ten feet high, were breaking just astern of the boat. As we dragged astern, I realized that we would soon be on the beach, in pieces. I snapped a divers weight belt over the anchor rode and pushed in down the line. Fortunately it worked its way down the slanting line rather rapidly until it snagged the shackle on the chain. Here it provided the additional weight required to let the flukes dig into the bottom, and we hung there until we could get the engine repaired, and head straight out to sea, to safety. The exact same trick saved the other boat, with only slight differences in the details.

Another common problem is putting a screw pin shackle to hold the anchor ring to the chain, or the chain to the rode. Screwed in finger tight, the screw pin can vibrate loose as the current causes the line to vibrate or strum. One classic example was an anchor I found in 60 feet of water, on the reef, with the purchase price sticker still on it. Within a foot of it was a brand new screw pin shackle, minus pin. I just hoped that the people who lost the anchor were still aboard the boat when they noticed it. If they were diving and came up to find the boat gone, they had a long swim to the beach. The cure is simple. Mouse the shackle. That is, use a piece of maleable stainless or copper wire thru the eye in the screw pin (thats why its there), and around the leg of the shackle. Its nearly impossible to unscrew the pin, now, much less have it vibrate out.

For divers and fishermen, who anchor on the reefs, where it is not uncommon to get the tips of the flukes under a small ledge, or in a hole in the rock, I highly recommend an anchor which has a sliding ring attached to the chain. The ring, and hence the point of pull, can be at the extreme end of the shank, or can slide to the flukes end, depending on the direction of pull. It can almost always be removed by pulling in line till one is directly above or somewhat ahead of the anchor, then giving some slack to let the anchor ring slide to the fluke end. A slight tug at this time will pull the flukes out from under the ledge and the anchor is free. Solid shank anchors with the ring permanently fixed at the end, will stay caught. I have several good ones in my garage that were left that way, and picked up by divers.

Spend a little more for a good, recoverable anchor, put on a long stout chain, mouse both shackles, add more than enough line of sufficient diameter to take a little wear, and be sure to provide enough scope when anchoring. It also pays to examine your rode regularly, for fraying across the bow cleat will occur. Done routinely, these precautions will assure that your boat will always be there when you surface from your dive.

Gentle winds, flat seas and good visibility!!

Most coastal dive shops would love to think of a way to keep divers in the water year round and to stop the constant loss of certified divers, who, not having a boat, stop diving a few months after obtaining their C-cards. I have long wondered why they do not go back to the tried and true techniques of the early days of diving? With a little encouragement, I do believe that the paddleboard would catch on as a very satisfactory way to reach the reefs a mile or two offshore, which would take care of most of the diving from Baker's Haulover to Jupiter Inlet.

I never dove from a boat in my first two years of SCUBA diving except when we dove from the Scripps Institution of Oceanography or the Navy UDT. All my private, non-work dives in La Jolla were done from homemade paddleboards.

Paddleboards were basically big surf boards, usually made of plywood and aircraft cement. They were a tad smaller than a beginners Windsurfer. Each diver had his own and we went out in groups of two or more, for there was a buddy system even back in the early 50's. Let me describe the rig and see if it doesn't have a place in South Florida.

Take a beginners surfboard or sailboard. Remove any straps, centerboard, mast and sails. Place two inch-wide strips of innertube rubber around the board, roughly amidships. You will soon find exactly where you want it because, with a piece of netting tied to the innertube, you will have a storage area on your paddleboard.

In this storage net goes your mask, snorkle, tank and regulator, weight belt, lobster tickler or speargun, underwater camera, etc. You will also have a small killick or mushroom anchor, of about three or four pounds and enough 1/8th inch nylon to reach bottom plus a little extra scope. 200 feet on a small reel would be great for anywhere a normal diver would want to go. This completes your basic paddleboard.

Carry it to the beach on your cartop carrier, take it down to the beach wherever they permit diving from the beach, place your gear under the netting and launch it next to your buddy. Once out of the surf, put on your fins and laying on the rear of the board, paddle out to the reef. They move handily under one manpower. I'd guess you could breast a knot and a half or two knot current. At the dive site drop your killick which only needs a modest grip because the board has very little drag in a current. Put on your gear and down you go, pulling your board after you anywhere on the reef.

Of course you fly a large DIVER DOWN flag to alert other boaters that there is a diver below, but you never get far from the paddleboard, dramatically reducing the danger of being hit by a boat. On a modified sailboard the flag can go in the mast step or centerboard well.

When I had a dive shop on McNab Road, many years ago I tried to get my partners to carry a couple of old sailboards so we could set up a scenario. As a group gathered to go to a diveboat we would find out which reef they were headed for. We'd leave with the paddleboards as they headed for their diveboat. We'd launch and be waiting for them when they got to the reef they planned to dive. When done diving we'd head for the beach, put boards and equipment in our cars and wait for them back at the shop.

I never could get them to try it although we did get a design for a unit much like the jet-skis of today, with a small motor and a water jet for safe propulsion and with a well for a tank and backpack and other storage space. A naval architect at Chris Craft designed it for us but it was never built or we'd be millionaires with the first jet-skis of all time!

The SCUBA kayak is a version of the paddleboard but too expensive for many wouldbe year round divers who could procure and rig their own paddleboard for probably less than $500.

If they wish, the dive shops can purchase surfboard or sailboard blems, rig them in an hour and make a nice profit while keeping most divers diving year round. They will have their own paddleboard at small expense after the initial purchase, for lack of boats is one of the big problems with new divers, and a paddleboard is no more expensive than a good dive computer!

People often inquire of me how the ocean got salty. I usually tell them the tale of the king who had a magic salt grinder that not only turned out salt when the handle was turned, but also had a magic handle which turned itself. Now salt was very valuable in the olden days, for it preserved food and was vital to animals, including man, who got too little salt in their diet. Thus the king was very glad as the grinder piled up salt in his back 40, and even when it filled his royal warehouses. But when it buried his castle and family, he threw it into the sea, where it continued to grind out salt to this day.

The interesting part of this whole myth is that there is a salt grinder that is constantly working to make the sea more salty! This, then, is the story of that salt grinder, which we call the hydrologic cycle. It is the true story of the continued accumulation of salt in the sea, and goes like this.

Since the time when the first significant amount of water accumulated on the face of the earth, some 4 billion years ago, it did something which we all recognize. It dissolved a little bit of the rocks and minerals across and thru which it flowed. The result was what we call hard water; water with a little dissolved material in it. Not enough to see, and often not really enough to taste, but there nevertheless, as we see when water droplets dry on a clean glass surface, and leave the dissolved minerals behind.

Water is a near universal solvent. Given enough time it will take almost anything into solution, including glass, diamonds, gold, stainless steel, etc. The water flows thru the earth as ground water, and into creeks which flow into rivers which, in turn, flow into the sea. The dissolved minerals flow with it. The water eventually evaporates and returns to the land as rain, to go thru the entire cycle again and pick up another little load of material to transport to the ocean. Over millions, or billions, of years, a great deal of dissolved materials is carried to, and left in, the sea. Thus the sea gets salty.

There is more to it than that, tho. Every time a volcano erupts it emits gases into the atmosphere, Some of these gases are washed into the soil or the ocean by rain, and they, too, add their load to the ground water and sea!. Among the gases are water vapor, chlorine, bromine, fluorine and iodine, which are present primarily as ions, ie, as chloride, bromide, fluoride and iodide. Another part of the vapor is carbon in the form of carbon dioxide. This carbonates the rain water and ground water into a very dilute solution of Perrier water, better known as carbonic acid. It is dilute, to be sure, but very destructive to silicate minerals which make up much of our earth. Feldspars, amphiboles and pyroxenes all succumb to the attack of this acid and release a wide variety of ions to the waters. Granite yields to rainwater attack over hundreds of thousands of years.

By the mechanism of volcanic emanations we get 1) the chloride, which makes up about 54% of the saltiness of the seawater, 2) the sulfate, from sulfurous emanations of the volcanos, like sulfur dioxide, etc., and 3) bromide, 4) bicarbonate, 5) boric acid and 6) fluoride. Weathering of the rocks under the attack of the rain and groundwater gives us ions leached from the rocks, like 7) sodium, which makes up about 32% of the salts in the sea, and 8) magnesium which contributes about 6%. It also provides 9) calcium, 10) potassium, and 11) strontium. These 11 major ions make up all but a very tiny fraction of one percent of the salt in the sea. The remaining fraction is so small that people ask why we even bother with it. The answer follows! We bother because the thousandth of a percent left contains all the nutrients, gases, heavy metals, most of the radioactivity etc., in the ocean. Without that tiny fraction there would be no life in the sea!! But thats another story.

The result of the natural salt grinder is seawater with about 3.6 percent of inorganic salts dissolved in it, or as oceanographers say, 36 parts per thousand. If you evaporate it, table salt and magnesium sulfate (epsom salts) make up about 95 percent of the salts.

Another interesting discovery of the last several decades is that the ocean floor is being pulled apart at the mid ocean rifts, and salt water is creeping down to the hot magma (melted rock) under the rifts, where it is heated up and rises to the surface again. During this passage it dissolves a lot of ions from the hot rock it comes in contact with. As it comes out of the rifts thru vents which squirt the hot water into the sea, a lot of very valuable metal sulfides are deposited in huge masses along the rifts. Minerals like iron pyrite (fools gold), and like the ores being mined in many places on the earths surface, are being formed now. Indeed we believe that the enormous copper ore deposits, that have been mined on the Mediterranean island of Cyprus (Latin: cuprus = copper) for many centuries, were deposited in a midocean rift and uplifted to form Cyprus.

In addition to the great ore deposits, the hot rift waters must also add materials to the seawater, and are believed to be the reason that certain dissolved materials are not present in the amounts that we thought they should be, based upon the hydrologic cycle. The ocean doesnt seem to have gotten saltier in the last 500 million years and it must be because the interior of the earth released enough water, as it released the gases and lava, to keep the salts diluted to 36 parts per thousand. For each 964 parts of new or juvenile water released from volcanoes, 36 parts of the various salt ions were also released onto the earths surface.

Most folks dont realize that table salt was the real commodity that kept the Middle East in business at the time of Christ. Salt caravans kept the trails open and the Biblical story of Sodom and Gomorrah, with the pillars of salt playing such a prominent part, was because they were salt shipment, and probably salt production, cities. Somebody who doesn't do a good job is not worth his salt. A good person is the salt of the earth. You can probably come up with a dozen more such expressions in which salt plays a prominent part. Gold, frankincense and myrrh were thus way behind salt as the commodities of the trade caravans until large land deposits of salt were discovered. At that time the salt pans where sea water was evaporated in shallow basins along the eastern end of the Mediterranean Sea, were largely abandoned, altho even today salt is made from seawater in the San Francisco and San Diego areas, in the Bahamas, etc.

Since magnesium salts crystallize out of evaporating seawater after most of the tablesalt has formed, that is the time to stop the evaporation by dumping the rest of the brine, now bitter with the taste of the magnesium ions (remember how milk of magnesia or epsom salts taste?). They call this brine bittern. Otherwise the salt would be too bitter and a very effective laxative. And with a brief story about this property, Ill stop.

Some years ago as I was leaving the Palmetto Park launching ramp, where I'd gone to get my SCUBA tanks filled at FORCE-E Dive Shop, an old lady came up to me and said, "Boys", and I liked her right away, "Boys, will you get me a five gallon jug of seawater while you are out?" I allowed as how it could be but we didnt know when we would be coming back. She said she'd be watching so we took her jug and filled it way offshore to avoid any contamination from the sewers and inlets off the east coast of Florida.

She was there when we got back. Overcome by curiosity, I asked her if she kept a salt water aquarium. She said no. Then, "You'll laugh at me if I tell you what I do with it", she said. We promised not to laugh and she said she drank a half cup every morning. "It keeps me regular", she said.

I'll bet it did. She got a good stiff dose of epsom salts each morning and she should have been regular as clockwork. Hope she doesn't die of high blood pressure from all the salt tho! Oh, and by the way, we rolled on the ground laughing!!