TUSCALOOSA, Ala. – Although nearly half of all the recorded extinctions of animal species during the past 500 years are nonmarine mollusks, such as freshwater clams and snails, their decline is largely ignored by the public and even most biologists, according to an article co-authored by a University of Alabama biologist and published in the latest issue of BioScience.

In the April 2004 issue of BioScience, a team of 16 experts from around the world report on the diversity and plight of what may be the world’s most endangered group of animals – nonmarine mollusks. Dr. Charles Lydeard, associate professor of biological sciences at UA, is the article’s lead author. Stephanie Clark, a post-doctoral research associate at UA, and Kathryn Perez, a UA graduate student, are among the article’s co-authors.

The World Conservation Union lists in the IUCN Red List of Threatened Species a total of 1,930 threatened nonmarine mollusks, which is nearly half the number of all known amphibian species, more than twice the number of shark and ray species, and nearly seven times the number of turtle species.

A staggering 42 percent of the 693 recorded extinctions of all animal species since the year 1500 are mollusks (260 gastropods and 31 bivalves), according to the article in the journal published by the American Institute of Biological Sciences.

Regrettably, nonmarine molluscan extinctions go largely unnoticed by the general public, most biologists, and by many conservation agencies, which focus their resources and energy on more charismatic vertebrate species, the authors state. The extraordinary decline of nonmarine mollusks is due directly to habitat destruction and disruption of natural ecosystem processes.

As an integral component of healthy ecosystems, molluscan diversity is valuable both for its own sake and as an indicator of conditions that may affect other species, including humans, the researchers say.

Nonmarine mollusks are members of the second most diverse group of animals, the phylum Mollusca, which includes snails, slugs, clams, and mussels and others. There are approximately 24,000 terrestrial and 7,000 freshwater mollusk species for which valid descriptions exist.

There are probably 11,000 to 40,000 undescribed terrestrial species and 3,000 to 10,000 undescribed freshwater species, according to the authors. Even the lower estimates exceed the number of all known species of birds, and the higher figures exceed the number of all known species of vertebrates.

BioScience publishes commentary and peer-reviewed articles covering a wide range of biological fields, including ecology. The journal has been published since 1964. The American Institute of Biological Sciences is an organization for professional scientific societies and organizations that are involved with biology. It represents 86 member societies and organizations with a combined membership of about 240,000.