Gremlin Pinza is a Gremlin who's caged in the Jungle Boat Ride. As Mickey is riding the boats toward the exit, he passes a small patch of land against the wall with a giant giraffe prop. Pinza is on this land under the giraffe's legs.
After he's free, Pinza helps Mickey at the end of the area by activating one of the cranks that opens the doors and drops the Sweepers into the Thinner. And if Mickey also frees Trigo, Habel, and Hyperion, he, along with them, repairs the last platform, allowing access to a Silver Pin.