CHATTANOOGA, TN (WRCB) -- Nearly two-dozen turtle hatchling have been born at the Tennessee Aquarium since the start of July. The Aquarium's collection of more than 500 turtles, from 75 different species, keeps the herpetologists (one who studies amphibians) quite busy.

"In addition to all of the exhibits with turtles, we care for a large number of pairs off exhibit. So we stay busy throughout the year," said Aquarium senior herpetologist Bill Hughes. "While many species nest at specific times of the year, they don't choose specific times of the day to lay eggs. So, we really have to keep a close eye on all of the enclosures to make sure we collect the eggs in a timely fashion for incubation."

Hughes reports eight yellow-blotched map turtles, Graptemys flavimaculata, this year. A few more could hatch at the Aquarium before the season is over. This species of map turtle is endemic to the Pascagoula River and some of its tributaries in Mississippi. "They are declining in the wild because of habitat loss and are currently federally-protected," Hughes said. Success with species like the yellow-blotched map turtle helps provide offspring that can be placed at other institutions accredited by the Association of Zoos and Aquariums (AZA). "We're then able to reach guests with important conservation messages about rare or protected species that cannot, or should not, be removed from the wild," said Dave Collins, the Aquarium's curator of forests.

The sex of these hatchlings depends on the incubation temperature. Aquarium experts are able to manage the temperature carefully to get an even number of male and female yellow-blotched map turtles. This is critical for the long-term success of any turtle breeding program. "This builds assurance colonies. If these species should disappear in the wild, they won't become totally extinct," said Collins. Adult yellow-blotched map turtles can be seen in the Aquarium's Delta and Pascagoula River exhibits.

The red-headed Amazon River turtle, Podocnemis erythrocephala, is listed as Vulnerable by the International Union for Conservation of Nature and Natural Resources, IUCN, but the reality of their status could be much grimmer. "The most recent information is from 1996 so we don't really know how many are left in the wild," said Hughes. "It's difficult to believe their populations have increased significantly since the last report." There are now seven new baby red-headed Amazon River turtles at the Aquarium. "In the previous years combined, we have only hatched five of this species," Hughes said. "We still have one egg incubating that appears to be viable." Aquarium guests can see an adult male red-headed Amazon turtle in the Rivers of the World Gallery.

The four-eyed turtle, Sacalia quadriocellata, is listed as Endangered by IUCN. The Aquarium has three new four-eyed turtle hatchlings. This species gets its name from the false eye markings on their necks. Hughes said these most recent babies hatched from eggs laid in April. The Aquarium displays a hatchling from last year in the nursery exhibit in the River Journey Turtle Gallery. Baby four-eyed turtles from previous years have been placed at other AZA institutions. The majority of the U.S. population of these turtles is at the Tennessee Aquarium, the only zoo or aquarium currently breeding this species. "Critically endangered species, including many Asian species such as the four-eyed turtle, face a very real threat of disappearing in the wild," said Collins. Guests can also see four-eyed turtles in the Asian River exhibit.

Finally, two Florida chicken turtles, Deirochelys reticularia chrysea, joined the rest of this recent baby boom at the Aquarium. This pair hatched from eggs laid at the end of January. This species is not threatened or endangered in the wild in spite of their common name. They were once commonly sold in southern markets as food. The meat was said to "taste like chicken." Collins says breeding success among these rather abundant turtles can help other endangered species. "Chicken turtles have unusual reproductive strategies," said Collins. "They breed in winter and their eggs need to be cooled for several weeks before being warmed to begin developing. Research in zoos and aquariums helps uncover these details. And that can lead to successful breeding of rare species for conservation purposes." Aquarium guests can see chicken turtles in the Delta exhibit.