Most of the applications of wireless sensor networks require the continuous coverage of a region of interest. The irregular deployment of the nodes, or their failure, could result in holes in the coverage, thus jeopardizing such requirement. Methods to recover the sensing capabilities usually demand the availability of redundant full-fledged nodes, whose relocation should heal the holes. These solutions, however, do not consider the high cost of obtaining redundant, typically complex, devices, nor that they could in turn fail. In this work, we propose a bio-inspired and emergent approach toward hole detection and healing using a swarm of resource-constrained agents with reduced sensing capabilities, whose behavior draws inspiration from the concepts underlying blood coagulation. The swarm follows three rules: activation, adhesion, and cohesion, adapted from the behavior exhibited by platelets during the human healing process. Relying only on local and relative information, the mobile agents can detect the holes border and place themselves in locally optimal positions to temporarily restore the service. To validate the algorithm, we have developed a distributed, multi-process simulator. Experimental results show that the proposed method efficiently detects and heals the holes, outperforming two state-of-the-art solutions. It also demonstrates good robustness and flexibility to agent failure.