 With a more streamlined form than other nurse sharks , the tawny nurse shark is believed to be a less <unk> , more active swimmer . The characteristics of its body , head , fins , and teeth are comparable to other active reef sharks sharing its range , such as the <unk> lemon shark ( <unk> <unk> ) . Tawny nurse sharks are primarily nocturnal , though they are said to be active at all hours off Madagascar , and in captivity they will become <unk> active if presented with food . During the day , groups of two dozen or more sharks can be found resting inside caves and under ledges , often stacked atop one another . Individual sharks have small home ranges that they consistently return to each day . 
