This paper considers the problem of maintaining the coverage degree of a wireless sensor network at an application specific level while keeping the sensing units of only a subset of sensor nodes active at any time to save energy. Two distributed coverage service protocols are proposed, namely, NCP (Neighbor-Based Coverage Protocol) and GCP (Grid-Based Coverage Protocol), which identify redundant sensor nodes for the desired degree of coverage to turn off their sensing units. NCP introduces a novel method for evaluation of the coverage degree of a node?s sensing region by its neighbors to determine its redundancy. GCP explores the idea of dividing the target area using a virtual hexagonal-grid during which all but one sensor node with the highest residual energy are identified as redundant for the coverage of the corresponding grid unit. Performance evaluations show that both protocols result in significant energy savings while providing differentiable coverage service in the wireless sensor network with low message and computational overhead.