The story revolves around Adam Lyon, a human. After a clerical error listed his surname as "Lion", Adam is forced to transfer from Chester Arthur Middle School to Charles Darwin Middle School, a school for local zoo animals. Shortly after his transfer, he is partnered with Jake Spidermonkey in gym (hence the title). While Jake enjoys having fun at the expense of others, he quickly becomes attached to Adam. The majority of the show's humor derives from Adam's attempts to reconcile his human limitations, as well as his outsider status, with the demands of an animal-centric school and social scene.
Much of Charles Darwin Middle School is modeled after specific habitats. There are fish tubes created so that the fish can breathe and swim around. There are also vines and bodies of water. Some animals like Bull Sharkowski use devices to allow them to live outside of their natural habitat. In Bull's case he uses what looks like headphones full of water that go around his gills. The main characters have been able to breathe in water in the early episodes for some mysterious reason.
Charles Darwin Middle School appears to be the only animal school around, as it is later explained in the episode "Uniformity." In the episode, there are high end east coast schools for animals. Also, there is a school for plants called Creeping Broad-Leaf Sedge Middle School (CBLSMS) where Jake is sent to due to a clerical error calling him a lion. The school competes against human schools in athletics and other events. In one episode where Adam signs up to return to his old school for a day transfer, all the teachers and staff seem to replicate their animal counterparts.
-  Australia
-  Chile
-  Latin America
- Cartoon Network (2006-2008,2009-present)(in Cartoon Pop / Cartoon Zaum)
-  North America
-  United Kingdom/Ireland
- Cartoon Network(2007-present)
-  Europe/Middle East/Africa/Asia
Two DVD volumes of the series have been released in Australia, the first on April 4, 2007 and the second on January 23, 2008. As of January 2010, there have been no further volumes released.