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
