JoJo, Brookfield Zoo’s silverback western lowland gorilla, suffered a fatal cardiac arrest Sunday during an emergency procedure. He had an acute illness, according to a post from the zoo on Facebook. “JoJo was very smart and learned new behaviors quickly during husbandry training sessions,” a @brookfieldzoo representative wrote in the post. “He was known for keeping order in the gorilla group by quickly breaking up squabbles and often showed his gentler and patient side when interacting with his offspring,” it continued. The 42-year-old gorilla was considered “geriatric,” the zoo wrote. He lived 10 years beyond the typical life span of a male gorilla in managed care. JoJo was brought to Brookfield in 2012 as a part of a breeding program aimed at bolstering the species. He moved into the Tropic World habitat and quickly got to work. The animal sired three gorillas: Nora in 2013, Zachary in 2015, and Ali in 2018. He fathered two more gorillas before he came to the park, including one at Lincoln Park Zoo and another at the Louisville Zoo. The offspring were consequential: Western lowland gorillas are critically endangered, the World Wildlife Foundation says. The species’ central African native populations have been hit hard by poaching and disease in the last 20 years, the WWF said. “The loss of JoJo is great, but his legacy will live on in the overall zoo population for this critically endangered species,” according to the post. Chicagoans responded to the news of JoJo’s passing by posting dozens of their own photos of the lionized gorilla on the zoo’s Facebook page, offering one last glimpse at the awe the animal inspired. Click the link in our bio for more. (Chuck Berman / Chicago Tribune)