Describe the first realization that a shark had entered the Matawan Creek.

On July 11, 1916, Renny Cartan, Jr., his cousin Johnson Cartan, and some other friends took off for the swimming hole at Matawan Creek. Renny jumped in the cool, dark waters but soon had a strange sensation tearing across his chest--something he had never experienced before or was able to identify. The splashing of the boys had drawn the shark, which bumped Renny, probably to get a sense of his size. Renny spotted something very large swimming near him and scrambled out of the water, bleeding from being scraped by the teeth-like covering on the shark's body.