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COLLECTING SHELLS

Tools and Collecting Tips by Dr. Gary Rosenberg
A well-equipped field collector makes use of many different tools depending on the habitat being investigated. Screens are good for sorting shells out of sand and mud, the size of the screen and its mesh depending on the size of the mollusks the collector is interested in finding. Nested sets of brass-framed screens with graduated mesh sizes are available from geology supply houses. Collectors can also make their own screens with wooden or plexiglass frames. Promising areas for screening on sand and mud flats sometimes can be recognized by the presence of snail trails and bivalve burrows. When snorkeling or scuba diving, some collectors use a sieve to sift sand from under rocks and coral slabs and in sandy pockets on the reef. In grass flats and other areas where sediment cannot easily be scooped into a screen or sieve, it can be fanned in with the hand or a small board. Screening can be an excellent way of finding small specimens that would otherwise escape notice.

Rocks and coral blocks cast up on shore often show the tell-tale circular or oval openings of the burrows of boring bivalves such as piddocks and date mussels. The shells can be collected by carefully excavating the burrows with hammer and chisel, although inevitably some specimens are smashed by an over-enthusiastic blow or an ill-timed slip. Other bivalves, such as false angel wings can be found boring in peat, and the shipworms bore in wood. When collecting shipworms, be careful to dissect the whole animal, which can be quite long, from the wood, because the shell valves are at the anterior end, and the calcareous pallets, which are essential for identification, are at the posterior end.

In reef areas, the best collecting is found in areas of dead coral rubble. When overturning dead coral slabs, prudent collectors grab the far side and lift it toward them, to allow lurking eels and other nasties to escape. Before examining the underside of the slab, take a quick look at the substrate below for mollusks attempting to crawl away or bury themselves. Next, scan the bottom of the slab for movement--some gastropods avoid light, and will start crawling to seek shelter. Many mollusks are well camouflaged, and careful searching often reveals cryptic shells such as chitons and byssally attached bivalves overlooked at first. Small shells hiding in crevices can be removed with tweezers. To reach more inaccessible specimens, some collectors carry mechanical fingers, which are used by mechanics to retrieve parts dropped into engines. Make sure always to return rocks and coral slabs to their original positions, otherwise sessile organisms growing on them will die.

Algal washing is an excellent way of obtaining live specimens of small species that otherwise are found only as worn specimens in the drift-line or when screening sand. Handfuls of marine algae or grass are pulled apart in a bucket to which fresh water (not sea water) is then added. Most mollusks, except for byssally attached clams, will drop to the bottom. The algae is then rinsed and removed piece by piece, leaving a residue for sorting. By washing only one species of algae at a time, the persistent collector can accumulate valuable data on habitat preferences of micromollusks.

Some shell collectors maintain a notebook in which they record ecological data in the field while it is still fresh in their minds. A station number keys information about each locality to the specimens collected there. The notebook should be written in pencil or indelible ink as it is likely to get wet in the field. A plastic station number label is make with a hand-held label maker (available at most hardware stores) and stored with the specimens. One system for assigning station numbers is to use the collector's initials and the last two digits of the year, e.g. GR96-13, GR96-14, GR96-15.

Before collecting in a given area, collectors should familiarize themselves with rules and regulations that might affect them. For example, some jurisdictions ban shell collecting, and others require permits or have restricted seasons. Collecting in some areas can be hazardous. People snorkeling in tropical waters for the first time can get sunburnt all the way to their finger-tips because the ultraviolet rays of the strong tropical sun can penetrate several feet underwater. Some methods of collecting are hazardous, for example nocturnal collecting. People collect at night, using waterproof flashlights, because many mollusks that hide during the day crawl about actively at night. However, it is easy to lose one's bearings at night, so be sure to leave two lights on the shore to serve as landmarks. Keeping track of time and tides is also important for safety, as it is easy to be stranded on an offshore sandbar or reef by a returning tide when one is engrossed in hunting for shells. Many other tips for shell collectors can be found in M.K. Jacobson (ed.) How to Study and Collect Shells, 4th ed. American Malacological Union.

Increasingly, rather than collecting shells, hobbyists are photographing the living animals and documenting their habitats. Often it is necessary to collect a few specimens in order to confirm identifications, but with experience, field identification is possible for most species. Repeated collecting and observation in one area in different seasons over a period of years can lead to an intimate knowledge of a fauna, and can be an important way of monitoring environmental health. If the species composition changes and some species become locally extinct, that can be a sign of environmental degradation. This kind of baseline information is not available for most local faunas and represents a realm where the amateur can make an important contribution. If we don't know what the fauna of an area was before an oil spill, how can we assess faunal recovery in its aftermath? The dead shells found in an area can give some idea of its fauna, but dead shells can persist for hundreds of years, and may not give an accurate indication of the species currently living in an area. Perhaps someday shellers will maintain life lists of species observed in the wild, as birders have done for many years, and will contribute to environmental monitoring as birders do.

Although considerable concern has been expressed in recent years about the possibility of over-collecting shells, the main threat to populations of marine mollusks is habitat destruction. To date, no species of marine mollusk is known to have been driven extinct by human activities, although this is not true for land and freshwater species. A single storm can cast millions of mollusks to die on the beach and in contrast the activities of shell collectors must be regarded as inconsequential. As long as humans are careful not to damage habitats, their activities are likely to be no more threatening to mollusks populations than those of other predators, providing they take only a few specimens of each species for their own use, and leave any juveniles and egg masses they might encounter to stock the next generation. In a few places that are subjected to heavy collecting pressures, strict rules concerning collecting have been enacted to ensure maintenance of adequate population levels. In some parts of the world, such as the Philippines, commercial shell collecting has resulted in severe local environmental degradation and depletion of molluscan populations. This is cause for much greater concern than the activities of individual collectors.

The above material has been adapted from Dr. Rosenberg's The Encyclopedia of Seashells,
published by Dorset Press, New York, 1992. Dr. Rosenberg is Associate Curator of Malacology at the
Academy of Natural Sciences of Philadelphia

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