Footage of an angry gorilla smacking a window in front of surprised visitors at Dallas Zoo.

The video, captured on December 13, shows the gorilla suddenly standing upright before whacking a glass partition with its hand, surprising a mother and her young daughter Myers, who are nearby.

The filmer later wrote online: ''Myers and her mommy got a surprise when one of the gorillas at the Dallas Zoo smacked the window.''

''Myers instantly assumes it’s a game and taps back.''