Chattanooga Zoo Hatches Hellbender Eggs

The Chattanooga Zoo is pleased to announce the successful hatching of a group of Hellbender eggs collected from the wild in East Tennessee. This is the first Hellbender hatching on Chattanooga Zoo grounds.

The Chattanooga Zoo has been working on Hellbender conservation on-site and infield since 2009. Due to catastrophic population collapse across the state, the Chattanooga Zoo teamed up with the Nashville Zoo’s Ectotherm department to collect eggs and begin setting up a head start program for east and middle Tennessee.

Working in partnership with the Tennessee Wildlife Resource Agency, the Nashville Zoo, The University of Tennessee, and Lee University, the Zoo will rear this group of juvenile Hellbenders for several years, until they are mature enough to monitor in the wild. Once they reach maturity, they will be released into a suitable stream in East Tennessee where species sightings no longer occur.

Creating head start programs for this species will give each individual animal a better chance of survival. Because they will be larger when released into the wild, they are easier to study, either by traditional methods or radio transmitters, which is essential for gathering data.

“Without human intervention of field research, head start programs, habitat protect and restoration, and animal reintroductions, we will lose the species to extinction. Our Ectotherm department and partners work diligently to better understand these animals in efforts to save and protect them for years to come,” David Hedrick, Chattanooga Zoo Ectotherm Keeper III.

Photo Credits: Chattanooga Zoo

Formerly found in streams throughout middle and east Tennessee, Hellbenders have experienced a steep decline throughout the state over the past thirty years. Declining populations are due to degraded water quality, sedimentation, pollution, and habitat loss from dams and other developments. A decade of field research has recently verified only six remaining streams that have healthy, self-sustaining populations in Tennessee. The Chattanooga Zoo hopes, through conservation efforts, public education, and partnerships, to be able to help reverse this trend of population decline in Tennessee Hellbenders.

The Hellbender (Cryptobranchus alleganiensis), also known as the Hellbender Salamander, is a species of Giant Salamander endemic to eastern North America. A member of the Cryptobranchidae family, Hellbenders are the only members of the Cryptobranchus genus, and are joined only by one other genus of salamanders (Andrias, which contains the Japanese and Chinese Giant Salamanders) at the family level.

The Hellbender is the largest aquatic salamander in the United States and grows to an average size of 12-15 inches, but they can be as long as 29 inches. They are nocturnal and exist on a diet of: crayfish, small fish, tadpoles, toads, and water snakes. They absorb oxygen from the water through their skin and can be found slowly crawling across the bottoms of clear, silt-free mountain streams.

The species is classified as “Near Threatened” on the IUCN Red List of Threatened Species. The Ozark Hellbender is particularly imperiled; drastic population declines were documented in the late 1980s and 1990s. It is listed as “Endangered” in Missouri and may soon be listed as Endangered federally.

Hellbenders are present in a number of Eastern US states, from southern New York to northern Georgia, including parts of Ohio, Pennsylvania, Maryland, West Virginia, Virginia, Kentucky, Illinois, Indiana, Tennessee, North Carolina, South Carolina, Alabama, Mississippi, Arkansas, Missouri, and even a small bit of Oklahoma and Kansas.

Vernacular names for the Hellbender include: snot otter, devil dog, mud-devil, grampus, Allegheny alligator, mud dog, water dog, and leverian water newt.

*The Chattanooga Zoo would like to express their gratitude for the financial assistance of local conservation partners in the effort to save the Hellbender: Terminal Brewhouse, and Mohawk Canoes.

Hellbender Salamander Hatches at Nashville Zoo

On October 11, 2015, the Nashville Zoo was successful in hatching an Eastern Hellbender that was the result of an egg being artificially fertilized with cryopreserved sperm; an achievement that had only been successful once before in an internal fertilizing Tiger Salamander in 2014. Moreover, this Hellbender is the first externally fertilizing salamander to be produced utilizing cryopreserved sperm.

“It’s a pretty big deal for the conservation of this species and all amphibians,” said Dale McGinnity, Ectotherm Curator. “This accomplishment means we can collect and preserve milt (seminal fluid containing sperm) from wild populations without removing Hellbenders from their environment. Cryopreserved sperm may remain viable for hundreds to thousands of years when kept at ultra-low temperatures with liquid nitrogen. ”

Many of the world’s amphibian species are disappearing from the planet due to pollution, habitat loss, and emerging diseases. Hellbenders, along with their close cousins the Japanese and Chinese Giant Salamanders, are the largest amphibians in the world; they are evolutionarily distinct and have remained relatively unchanged since the age of the dinosaurs. All three species are now in decline and may be threatened with extinction unless conservation programs are developed.

Photo Credits: Nashville Zoo and Sherri Reinsch

The St. Louis Zoo reproduced Ozark Hellbenders naturally in an artificial stream system for the first time in 2011. The following year, Nashville Zoo successfully hatched two Hellbenders using artificial fertilization. The latest accomplishment is one more step in developing assisted reproductive technology (ART) for captive Hellbenders.

Once ART is fully developed, milt collected and cryopreserved from specimens may be used to fertilize eggs to create a genetically diverse group to boost isolated wild populations. In the future, cryopreserved sperm may be utilized to fertilize eggs to repopulate extinct populations. Nashville Zoo staff has already cryopreserved milt from 4 watersheds, which is believed to be the first gene bank developed for any salamander species.

“We really could not have done this alone,” said McGinnity. “Our Zoo’s Amphibian Specialist, Sherri Reinsch, and our Veterinary staff made the project possible. This success would not have been possible without the collaboration other researchers including Dr. Robert Browne, an Australian cryobiologist; Dr. Vance Trudeau, a Canadian endocrinologist; Dr. Joe Greathouse; Dr. Michael Freake; Dr. Brian Miller; Dr. Dalen Agnew; Dr. Carla Carleton; and Dr. Sally Nofs. A special thanks goes to Bill Reeves, the Chief of Biodiversity for the Tennessee Wildlife Resources Agency for the State Wildlife Grant that helped to fund this work which also included statewide surveys, gene banking, disease testing, and genetic work for hellbenders in Tennessee.”

Nashville Zoo Makes History with First Captive Breeding of Eastern Hellbenders!

Nashville Zoo is pleased to announce the captive breeding of Eastern Hellbenders for the first time as well as the first controlled breeding of any Hellbenders using biotechnology. The two Hellbenders were successfully hatched from eggs produced and artificially fertilized from the Zoo’s long-term captive animals.

“The successful hatching of the two Hellbenders is a result of a long-term collaborative project with a group of international researchers dedicated to saving this species,” said Dale McGinnity, ectotherm curator at Nashville Zoo. “This is an important first step and is in line with the Zoo’s commitment to the conservation and propagation of rare species.”

 An adult Ozark Hellbender, one of the world's largest Salamanders...

One of Nashville Zoo's adult Hellbenders...

Learn more about Nashville Zoo's Hellbender breeding efforts in the video below.

The two offspring were produced from a group of four Hellbenders living in an off-exhibit facility at the Zoo. 

“It has taken five years to develop assisted reproductive technologies for captive hellbenders,” said McGinnity. “We hope that with further refinement over the next few years, this species can be reliably reproduced using these techniques. This technology may then be used with a gene bank of cryopreserved sperm for Eastern hellbenders housed at the Nashville Zoo, to produce genetically diverse and fit offspring to suit various conservation needs.”

So small... for now... Photo credit: 1 & 4; Aimee Stubbs / Nashville Zoo, 2; U.S. Fish & Wildlife, 3; Christian Sperka / Nashville Zoo.