Deep Tek Tahoe & Shell Wars

E.R. Cross

I enjoyed the interesting article on Lake Tahoe by Bruce Watkins in the June 99 Skin Diver. For me it was like a stroll down dive-memory lane. I agree with Bruce on at least one aspect of that beautiful lake: it's cold. However, there are some dissimilarities. In late 1948, I made a couple of commercial dives using an Mk-V helmet suit to a depth of 260 feet. As Bruce pointed out, the viz was shining with the clarity of gems. I don't know how deep Bruce penetrated, but as you descend into the lake, color becomes drastically fainter. And fish are larger at greater depth, too. I classed them all as very large trout. Like Bruce, I also found that the bottom was strewn with great slabs of rock rather than with boulders. The calm down there was so overwhelming I became uneasy. Perhaps it was the loneliness after all, the next closest diver was probably somewhere in San Francisco Bay. I worked in the area offshore of the Singer estate. I have never returned to Tahoe and doubt I'd recognize it if I did.
He Sells Sea Shells
Considering the stories of sailors and divers, there seems to be little doubt about the food choices of marine life. At nearly all depths, the big eat the small and the smaller eat the smallest. This is true only to a very limited extent. Some sea creatures are carnivorous, some are herbivorous while the un-picky omnivores don't care whether it's a plant or an animal. A close look at our underwater neighbors reveals that there are many food choices among the ocean's flora and fauna. I once photographed a Cassis cornuta (Helmet Shell) that was experiencing some prickly sensations it was eating an urchin when I carefully pried it off its intended meal. The Helmet Shell was carefully replaced on the spiny urchin. Three days later there was nothing but a row of spines.
In my several years of diving I have studied many other feeding events of marine life. On August 15, back in 1963, a three-inch-long Cymatium pyrum killed and ate two bivalves in three hours (one an inch long, the other an inch and a half). The next day Conus textile (a 21/2-inch cone shell) killed and ate a Bursa cruentata (a 3/4-inch gastropod) in two hours, but in early September, C. textile stung and ate the Cymatium pyruma face-saving measure on behalf of the bivalves.
Usually the mollusk known as Distorsio anus is found well-hidden beneath small to medium pieces of coral boulders in 60 to 100 feet of tropical water. On one occasion I found two specimens on a hard substrate out in the open at a depth of just over 100 feet. I collected these for study in my saltwater aquarium.
By October 12, the Distorsio anuses were doing well. One specimen had deposited an egg cluster on the side of the aquarium at the edge of the water. Next day, the second D. anus had also deposited an egg cluster near the first cluster of eggs. On October 16 Cymatium pileare was noted eating one egg cluster, and by the 18th, a sea urchin was noted eating the other. The sea urchin was removed from the eggs and placed on the opposite side of the aquarium. In two hours the urchin was back eating the eggs. The second time I moved the urchin it was back eating the eggs within three hours. Thus go the noshing habits of marine mollusks.
A reader recently wrote asking where information about diving-related marine industries could be found.
Besides Skin Diver, a good insight into the many aspects of diving can be found in the monthly Sea Technology (Compass Publications, Inc., Ste. 1000, 1117 N. 19th St., Arlington, VA 22209). Of particular help is their annual supplement Buyers Guide Directory. For example, Buyers has an extensive section on manufacturers and distributors of decompression chambers, ROVs (including AUVs and UUVs) and all manner of equipment for working divers.
A publication catering to a different set of diving needs would be Ocean News and Technology (Technology Systems Corp., P.O. Box 2174, Palm City, Florida, 34991-7174). These publications will keep interested rec (or wreck) divers up-to-date on developments in the industry, so write them directly for info.
A couple of Navy boys wanting to decorate their classroom and adjoining club room wrote me asking, Are there any established businesses that sell large (5 by 7 inches or larger) B/W or color prints or color transparencies of underwater and diving-related subjects? Ever since we began reading Skin Diver, we have closely followed the technical sections. We now want to complete our collection of specialized illustrations for reference and training material. Please advise CrossTalk, so I can help these swabbies out.