On October 11, 2025, visitors at the San Diego Zoo witnessed an astonishing—and unnerving—scene. A 10-year-old western lowland gorilla named Denny charged full speed into the viewing barrier, herculean in force, and left a massive crack sprawling across the enclosure’s tempered glass. The moment was captured on video, prompting gasps, trembling frames, and comparisons by onlookers to an earthquake. Though no one was injured—neither Denny nor another gorilla in the habitat—the incident sparked questions about gorilla behavior, enclosure safety, and the emotional impact on zoo visitors.
This dramatic event offers more than a viral snippet—it gives us a window into primate psychology, zoo safety protocols, and the delicate balance between captive animal welfare and public viewing. Below, we examine the incident in detail, explore possible causes, assess the zoo’s response, and reflect on what this says about our relationship with animals in human care.
The Incident: What Happened
According to the San Diego Zoo Wildlife Alliance, Denny collided with one of three layered tempered glass panels in the gorilla habitat, fracturing the first layer. People.com The crack was extensive, spider-webbing across the surface, and startled guests described the impact as “earthquake-like.” People.com Witnesses reported that the gorilla appeared to take a running start, then leapt into the barrier. One visitor, Katya Sutil, estimated the crack spanned about six feet. People.com+1 She also recalled falling back in shock as the glass shuddered.
While the crowd reacted in alarm, zoo officials confirmed that both gorillas present were unharmed. People.com They immediately closed off the gorilla viewing habitat and relocated Denny and his companion to behind-the-scenes enclosures until the damaged panel could be safely replaced.
Why Did Denny Do That? Behavioral Context
The San Diego Zoo Wildlife Alliance statement noted that such behavior, though dramatic, is not necessarily abnormal—especially in adolescent male gorillas. Young males often display bursts of energy: charging, dragging objects, running laterally, or otherwise showing off strength or testing boundaries are part of their natural behavioral repertoire. People.com In captivity, these expressions sometimes manifest more forcefully, especially when environmental—or social—conditions prompt frustration or stimulation…