by Rachael O'Neil | CBS 11By Staff

FORT WORTH (CBSDFW.COM) – The world’s first Houston toads produced by in vitro fertilization using frozen sperm are at the Fort Worth Zoo.

The zoo is trying to maximize their population since there are fewer than 400 remaining in the wild.

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“It’s very concerning. Amphibians are bio indicators for a healthy environment and when these animals start to decline or disappear, it’s a red flag for us,” explained Diane Barber, curator of ectotherms at The Fort Worth Zoo.

It’s also a major problem for the animal food chain.

The Houston toads are vital for predators who feed on them.

Houston toads (CBS 11)

Uri and Viola who were named after the winter storms were created by IVF and hatched in February – their siblings are in the wild.

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“The in vitro fertilization, we can select 200 to 300 eggs at a time from one female and then pair those eggs with sperm from a particular male and then we can repeat the process and use sperm from a different male,” said Carrie Vance, Associate Research Professor at Mississippi State University. “So females can produce many different cohorts each with a different male.”

From the time the sperm and eggs are mixed to the time they transform into Houston toads only takes about a month.

While lack of reproduction is a huge reason why the species is endangered, Vance says other factors play a part.

Houston toads (CBS 11)

“In the wild, there’s a lot of habitat loss. There’s also toxic poisons, climate change is a big one altering their ability to survive,” Vance said.

But with steady efforts, in the near future, herpetologists are hopeful Houston toads won’t face the threat of being extinct.

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The Fort Worth Zoo has been nominated again by USA Today’s North America’s 10 Best Zoos. To vote, click here. Staff