Seashells are certainly diverse
and widespread. They are loved and enjoyed by many, and have been
for thousands of years. People around the world love collecting,
cleaning, and displaying these ocean treasures.
This article is intended to bring attention to something
treasured by many; seashells.
Seashells liter the shores of beaches around the world. They
serve as jewelry, currency, mementos, toys, decorations, cook
ware, and an abundance of other ways. In fact shells “have
stimulated the artistic, promoted ideas in design and
architecture, inspired musicians and poets, and have led to the
publication of some of the most beautiful books ever produced for
natural historians” (Oceana 2004). Seashells are made by
marine invertebrates. These invertebrates are typically in the
phylum Mollusca. There are seven extant (living) and in regards
to the molluscs about 3/4 of the species are contained in the
class Gastropoda (gastropods). With over 25,000 species of snails
(gastropods) and 10,000 species of bivalves (bivalvia) alone, the
phylum can most certainly be considered speciose (Oceana 2004).
Although other publications list gastropods having greater
diversity, near 2/3 of the phylum at approximately 50,000 living
species (Calfo & Fenner 2003).
So what are seashells? Well they are obviously the skeletal
remains of molluscs. These skeletal structures serve as
protective barriers for the animal’s soft fleshy body. They
are used for catching food, holding onto substrate, movement,
body shape, and protection. How did they come about? We don’t
Two main theories exist on the origin of seashells. Some
scientists like Sean Brennan of the US Geological Survey
postulate that incredibly high ocean calcium levels may have
favored organisms that could excrete calcium as a waste particle.
Of course, this waste particle being shell. This theory is
supported by geologist Tim Lowenstein of State University New
York. Lowenstein and colleagues have used x-rays to analyze water
pockets that are millions of years old. This group has speculated
that their findings of high calcium levels about 540 million
years ago may have been responsible for the “Cambrian
Explosion” of shelled organisms.
The second popular theory of shell origin is of course for
defense mechanisms. This theory is supported by Steven Stanley of
Johns Hopkins University. Looking at molluscs of today the
function of defense is undeniably existent. However the defensive
needs of early shell producers is unknown. Additionally, there
exist high costs involved in producing shells. If ridding calcium
were the only purpose than a precipitate crystal would be
excreted. The fact that animals invest energy into making and
maintaining these shell structures indicates that they are
receiving some sort of benefit from them.
While the debate continues on the origin of seashells, some
things are certain. By looking at the shells and the animals
which produce them we can certainly learn a lot about these
wonderful creatures. Weather used as decorations, clothing, or
currency, these items are continue to serve an important role in
societies around the world.
This article is dedicated to my wife, Marzena Blundell. She is
truly a lover of the sea and her appreciation for seashells is
unmatched. Raised at sea as a pirate, she has grown into a great
beachcombing conchologist and advocate for marine ecosystems. If
only everyone could enjoy the oceans as much as she.
This article would not have been possible without the help and
encouragement of Aric Blitch. His contributions with the
paleogeographic information were vital. My sincere thank you to
Aric for inspiring this project.
Additional appreciation is owed to the wonderful folks on
Blundell Street, London England; their publications foster
appreciation for all marine life.
Funding for this project was provided by the Aquatic &
Terrestrial Research Team.
Adam Blundell M.S. works in Marine Ecology, and in Pathology
for the University of Utah. He is also Director of The Aquatic
& Terrestrial Research Team, a group which utilizes research
projects to bring together hobbyists and scientists. His vision
is to see this type of collaboration lead to further advancements
in aquarium husbandry. While not in the lab he is the president
of one of the Nation’s largest hobbyist clubs, the Wasatch
Marine Aquarium Society
has earned a BS in Marine Biology and an MS in the Natural
Resource and Health fields. Adam can be found at
References and Readings
- Berger Foundation (2005), “The Birth of Venus-
- Calfo, A., Fenner, R. (2003), “Reef
Invertebrates”, Reading Trees & Wet Web Media
- Holland, J.S., (2004), “In Search of Shells’
Origins”, National Geographic, Vol 206 No 5, USA.
- Lowenstein, T.K. (2001), “Oscillation in Phanerozoic
Seawater Chemistry: evidence from fluid inclusions”,
Science, No 294, pg 1086-1088, USA.
- Oceana (2004), “Shells”, Quantum Publishing Ltd,
6 Blundell Street London, England.
- Whitfield, J., (2001), “Salt Hold Samples of Ancient
Seas”, Nature, USA.