Earthsky Interviews
Private: Shell Collecting
02-21-2002 - Biodiversity
_JB:_ Shells are created by soft-bodied animals called mollusks. A tiny shell covers a newly-hatched mollusk. Calcium carbonate from their food or water is used to enlarge the shell as the mollusk grows. Many shells are beautifully curved and in gemstone colors. There are between 50 and 200 thousand different species of mollusks, depending on who’s counting. Each has a different kind of shell.
_DB:_ Maybe you’re saying, “studying shells sounds great, but I don’t live near the beach.” But mollusks are everywhere – in forests, grasslands and even deserts. Land snails may hide in leaf litter or on tree trunks – and mussels burrow into sand under streambeds.
_JB:_ Do be aware, though – in some coastal areas, shell collecting is banned, or limited to certain seasons. Other than that, it’s easy – and you don’t need a lot of expensive gear. You’ll want a notebook – so you can jot down where you collected each shell and the date. An old window screen is handy for sifting through beach sand, mud, or leaf litter. A magnifying glass or hand lens is useful. A collection of containers will keep your shells from being crushed when you carry them home. And a basic field guide can help you identify what you find.
_DB:_ For more, come to today’s show at earthsky.org. Thanks to the “U.S. Forest Service”:http://www.fs.fed.us/ and to the “National Fish and Wildlife Foundation”:http://www.nfwf.org/. We’re Block and Byrd for Earth and Sky.
The following individual was interviewed for today’s show. Our thanks to:
Dr. Timothy A. Pearce
Curator of Mollusks Delaware Museum of Natural History
Links and other info:
Delaware Museum of Natural History, “Mollusk Department”:http://www.delmnh.org/malnf.htm
“Website (hosted by the Philadelphia Academy of Natural Sciences) of the Conchologists of America,”:http://coa.acnatsci.org/conchnet/ “an international organization devoted to the interests of shell collectors.”
“The Bailey-Matthews Shell Museum on Sanibel Island in Florida”:http://www.shellmuseum.org/ (Sanibel is a popular shell-collecting destination)
Author’s notes:
There’s been much debate in the shell-collecting world about whether collecting is harmful to mollusk populations. Clearly, in some places, the answer is “Yes”; over-enthusiastic collecting of colorful tree snails in Hawaii and Florida has had a serious impact on these species. In the Solomon Islands, one tree snail became so valued by collectors, people were cutting down trees to get snails to sell. (The species is now protected under CITES and selling it is prohibited.)
Despite these examples, experts say that in general, the biggest threat to mollusks is not collecting but degradation and/ or loss of habitat. When coastal land is developed, for example, the load of silt washing off into the ocean often increases-and marine mollusks can”t cope. In the United States, many freshwater mussels are endangered because the rivers where they live are polluted, or because dams have changed the habitat, or because of dredging for navigation.