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December 20, 2021

More Than 1,000 Hellbenders Hatch at the Saint Louis Zoo in Fall 2021

The Saint Louis Zoo, the Missouri Department of Conservation (MDC) and U.S. Fish & Wildlife Service (USFWS) announce continuing achievement in hellbender conservation with the recent hatching of endangered hellbenders at the Zoo.

November marked the 10th anniversary of the world’s first successful zoo-bred Ozark hellbenders hatching

The Saint Louis Zoo, the Missouri Department of Conservation (MDC) and U.S. Fish & Wildlife Service (USFWS) announce continuing achievement in hellbender conservation with the recent hatching of endangered hellbenders at the Zoo.

From October through early December 2021, 750 Saint Louis Zoo-bred Ozark hellbenders hatched at the Charles H. Hoessle Herpetarium at the Zoo. In addition, 583 Ozark and eastern hellbenders hatched from eggs that MDC brought to the Zoo from Missouri river systems. A total of 1,333 newly hatched baby hellbenders are being cared for by experienced and dedicated herpetology keepers in a private area at the Herpetarium.

Notably, the Zoo-bred hatchlings are second-generation offspring of several males that 10 years ago, in November 2011, were among the world’s first successful zoo-bred Ozark hellbenders to hatch at the Saint Louis Zoo. The Zoo made conservation breeding history again in 2018 with the first-ever hatching of second-generation zoo-bred Ozark hellbenders. Propagation and head-starting of this species at the Zoo has resulted in over 12,000 successful hatchlings since 2011.

“Over the last decade, Zoo animal care professionals have continued to successfully care for and reproduce Ozark hellbenders,” said Lauren Augustine, Curator of Herpetology at the Zoo and Director of the Saint Louis Zoo WildCare Institute Ron Goellner Center for Hellbender Conservation. “Each year the keepers collect extensive data on the reproduction and growth of these amazing salamanders. It is the dedication and passion of these keepers that makes this conservation breeding program such a huge success that continues to improve and evolve each year.”

“It is such an amazing partnership with the Saint Louis Zoo to save an endangered amphibian,” said Jeff Briggler, Ph.D., State Herpetologist with the Missouri Department of Conservation. “Ten to 15 years ago, the future of hellbenders in Missouri was in doubt, but with the successful Saint Louis Zoo-breeding and rearing of the young, the future looks more promising.”

Hellbender Breeding and Conservation

The Saint Louis Zoo WildCare Institute Ron Goellner Center for Hellbender Conservation is a Saint Louis Zoo-based effort aimed at conserving native hellbender populations in Missouri.

The hellbender propagation facilities at the Zoo include two large outdoor streams that currently house breeding groups of Ozark hellbenders hatched at the Zoo in 2011. The streams have natural gravel, large rocks for hiding and artificial nest boxes for egg laying. A nearby building houses state-of-the-art life support equipment used to filter the water and maintain the streams at the proper temperature. In addition, four quarantined, climate-controlled rooms behind the scenes of the Herpetarium at the Zoo are the headquarters for the program.

“Thanks in part to the construction of efficient hellbender rearing systems, which provide the ideal environment for these animals to thrive, the Zoo is able to contribute to the recovery of hellbenders by managing a sustainable breeding population in human care,” said Augustine.

The facilities recreate hellbender habitat with closely monitored temperatures, pumps to maintain highly oxygenated water, and filtration systems to provide specific water quality parameters. The largest room includes a 32-foot simulated stream and houses a breeding group of adult eastern hellbenders.

The animal care team meticulously cares for these animals and systems. The Zoo’s Life Support Systems team plays a critical role in constructing and maintaining these systems that provide the ideal habitat for the hellbenders at the Zoo.

In addition to the breeding efforts, the Zoo also has been head-starting juvenile Ozark and eastern hellbenders, hatched from eggs collected in the wild, for future release. Currently, the Zoo has around 2,400 hellbenders, including the newest hatchlings, at the Herpetarium.

Hellbenders Released to Ozark Streams in Summer 2021

Once the Zoo-bred larvae are 2 to 8 years old, they can then be released into their natural habitat — the Ozark aquatic ecosystem.

Over 800 Ozark and eastern hellbenders raised from eggs at the Zoo were released into their native Missouri Ozark rivers in summer 2021 by MDC, in cooperation with the Zoo and USFWS. Since 2008, 9,476 Saint Louis Zoo-raised endangered hellbenders (8,599 Ozark and 877 eastern) have been reintroduced to the wild in Missouri. MDC biologists are monitoring the success of these released animals in the wild.

About Hellbenders — An Endangered Species

The official endangered species of the state of Missouri, hellbenders are the largest aquatic salamanders in North America. Missouri is the only state that has both subspecies — the Ozark hellbender (Cryptobranchus alleganiensis bishopi) and the eastern hellbender (Cryptobranchus alleganiensis alleganiensis). Both are listed as state endangered in Missouri, and the Ozark hellbender also is federally endangered by the USFWS.

Both Ozark and eastern hellbender populations in Missouri have declined more than 70 percent over the past 40 years. A population assessment indicated that all hellbender populations have a high risk of extinction (above 96%) over the next 75 years, unless populations are bolstered. Based upon these results, zoo propagation and head-starting were deemed essential to the long-term recovery of hellbenders in Missouri.

The Ozark hellbender can reach lengths up to 20 inches. Also known by the colloquial names of "snot otter" and "old lasagna sides," the adult hellbender is one of the largest species of salamanders in North America, with its closest relatives being the giant salamanders of China and Japan. It has a restricted range and is only found in the cold-water rivers of south-central Missouri and adjacent north-central Arkansas. Hellbenders have broad flat heads, small lidless eyes and pronounced skin folds on the sides of their body. They can live 25+ years, and their diet includes crayfish, fish, worms and snails. Large rocks on the river bottom provide refuge and nesting sites.

About the Partners

The Missouri Department of Conservation protects and manages the fish, forest and wildlife resources of the state of Missouri. The state agency facilitates citizens' participation in resource management, sustainable fishing and hunting, and provides opportunities to experience, enjoy and learn about nature. For more information, visit

Home to over 14,000 animals, representing nearly 500 species, the Saint Louis Zoo is recognized worldwide for its innovative approaches to animal care and management, wildlife conservation, research, and education. One of the few free zoos in the nation, the Saint Louis Zoo attracts approximately 3 million visitors annually and is the most-visited attraction in the region. Accredited by the Association of Zoos and Aquariums (AZA), the Saint Louis Zoo is part of an elite group of institutions that meet the highest standards in animal care as well as provide fun, safe and educational family experiences. The Saint Louis Zoo and the other AZA-accredited institutions collectively dedicate millions of dollars annually to support scientific research, conservation and education programs. For more information, visit

The mission of the U.S. Fish & Wildlife Service is to work with others to conserve, protect and enhance fish, wildlife, and plants and their habitats for the continuing benefit of the American people. For more information, visit