AZA News Releases

Shells and Scales: Three Animals You’d Never Notice Unless They Were Gone

Silver Spring, MD – They may not be as well-known by the 180 million people who visit Association of Zoos and Aquariums (AZA)-accredited zoos and aquariums each year, but desert pupfish, freshwater mussels, and Polynesian tree snails play important roles in their respective ecosystems. Additionally, if it had not been for the hard work of AZA-accredited zoos and aquariums and their conservation partners, some of these – and many other – animals would have already vanished from the earth.

“The 228 accredited members of the Association of Zoos and Aquariums continue to build upon their history and expertise of saving endangered species,” said AZA President & CEO Jim Maddy. “That tradition includes breeding programs that coordinate across many institutions to ensure healthy genetic and demographic diversity and partnerships with local, national, and international conservation organizations working on the recovery of these species.”

With a growing number of human-influenced threats confronting animals around the world, including poaching, deforestation, and an expanding population that already exceeds 7 billion people, we are facing what some scientists are calling the “Sixth Extinction.” However, with escalating engagement by AZA-accredited zoos and aquariums and their partners, there is good news in the face of this extinction crisis. From the Florida manatee to the California condor, the Hawaiian crow to the Puerto Rican crested toad, and the Chinese alligator to the American bison, AZA-accredited zoos and aquariums have been the leaders in putting efforts in place to protect these animals and dozens more.

Fish and mollusks are among some of the oldest groups of animals still alive today, pre-dating even the earliest insects.  Despite hundreds of millions of years of evolutionary success, many of these species are vulnerable to a variety of threats, and their future is uncertain.  AZA-accredited zoos and aquariums are doing everything they can to protect the most imperiled fish and mollusks from extinction. 

Over the next several months, AZA-accredited zoos and aquariums will be celebrating these initiatives and inviting the public to support efforts to save even more species.  In November, we gave thanks for the variety of birds that are being saved from extinction and through December, we’re spotlighting fish and mollusk species, including:           

Freshwater mussels – Found in the rivers and streams that traverse the North American continent, these bivalves are essentially living water filters, with some individuals capable of moving eight gallons of freshwater through their systems every single day.  Freshwater mussels prevent buildups of algae and bacteria and are in turn preyed upon by animals such as fish and birds.  Nearly 300 species live in the United States alone, many of which are threatened by pollution, damming, and competition from the invasive zebra mussel.  Scientists at the Columbus Zoo and Aquarium have collaborated with local wildlife agencies to establish the Freshwater Mussel Conservation and Research Center (FMCRC), one of only 10 freshwater mussel conservation facilities in North America, to assist in the propagation and conservation of highly endangered freshwater mussel species. Over a five-year period alone, the Center reintroduced 6,200 endangered northern riffleshell mussels to Ohio waterways, the largest reintroduction ever to occur in Ohio. The riffleshell mussels are tagged with microchips so that they can be identified during annual surveys, and thus far the survival rate of reintroduced mussels has been extremely high.           

Desert pupfish – You wouldn’t think to look for fish in the desert, but this hardy species thrives in super-salty ponds and streams scattered throughout the American southwest.  In fact, closely-related pupfish species found in isolated bodies of water offer evidence that a series of prehistoric desert lakes were once connected.  These days, the desert pupfish is threatened by human developments and invasive species that compete for the precious little aquatic habitat that remains.  Under the leadership of the Phoenix Zoo and The Living Desert, the desert pupfish is being bred in captivity and released into protected areas so that it can carry on the story of the desert’s history. With their abilities to live in some of the most extreme desert environments, these fish demonstrate the incredible range of adaptations found in healthy ecosystems.           

Polynesian tree snail (Partula nodosa) – Considered among the smallest of all endangered species, this species of partula snail is already extinct in the wild and would be gone completely were it not for the work of AZA-accredited zoos (Akron Zoo, Detroit Zoo, Disney's Animal Kingdom, Saint Louis Zoo, and Woodland Park Zoo) and international partners that are breeding these snails for reintroduction in their native range in the South Pacific.  Like so many other mollusks, the Polynesian tree snail declined from the introduction of an invasive species – in this case, a predatory snail that was introduced to control the population of yet another introduced snail. These snails were first described from specimens collected by the British explorer Captain James Cook, have been the subject of extensive field and laboratory research, are prominent in Polynesia’s cultural history, and play important roles in nutrient recycling and in the food chain of their native ecosystem.

For a list of AZA-accredited zoos and aquariums where you can see some of these incredible animals in person, please visit the AZA website:

About AZA

Founded in 1924, the Association of Zoos and Aquariums is a nonprofit organization dedicated to the advancement of zoos and aquariums in the areas of conservation, animal welfare, education, science, and recreation. AZA is the accrediting body for the top zoos and aquariums in the United States and six other countries. Look for the AZA accreditation logo whenever you visit a zoo or aquarium as your assurance that you are supporting a facility dedicated to providing excellent care for animals, a great experience for you, and a better future for all living things. The AZA is a leader in saving species and your link to helping animals all over the world. To learn more, visit

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