All 54 Stingrays Of Chicago’s Brookfield Zoo Die At Once.

All 54 stingrays of Chicago’s Brookfield Zoo have died after the oxygen levels in their tank dropped to dangerous low levels on Friday.

The malfunction caused four southern stingrays and 50 cownose rays, all born in captivity, to die, the zoo wrote on its Facebook page.

The zoo said that staff responded immediately to raise oxygen levels back to normal and veterinarians quickly arrived at the scene to tend to affected animals, however none of the rays survived. (Scroll down for the video.)

1. All 54 stingrays in Brookfield Zoo’s Stingray Bay habitat died on Friday after oxygen levels in their tank fell to dangerous low levels (photo: Jim Schulz / Chicago Zoological Society).

All 54 Stingrays Of Chicago's Brookfield Zoo Die At Once.

Bill Zeigler, senior vice president of animal programs for the Chicago Zoological Society, which operates the zoo, said:

We are devastated by the tragic loss of these animals.

Our staff did everything possible to try and save the animals, but the situation could not be reversed.

Zoo officials are currently examining the life support system to figure out what caused the malfunction.

The Chicago Zoological Society has decided to keep the stingray exhibit closed for the time being. It has been operating since 2007.

2. The malfunction caused four southern stingrays and 50 cownose rays, all born in captivity, to die (photo: Jim Schulz / Chicago Zoological Society).

All 54 Stingrays Of Chicago's Brookfield Zoo Die At Once.

That wasn’t the first time there was a problem with the exhibit, nor were these 54 stingrays the first casualties. Speaking to CNN, spokeswoman Sondra Katzen said:

We had a malfunction of a different type back in 2008. It was a water temperature increase, and the exhibit temperature increased by about 10 degrees, and we lost about 16 stingrays in that.

Eight sharks and three horseshoe crabs were also living inside the tank at the time, but survived.

The system had been updated following that tragedy and a new automated system that checks levels was installed.

3. Dozens of stingrays killed in a zoo accident.

Read more: Facebook, CNN.

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