Current encryption systems face increasing challenges from ever more sophisticated attacks, motivating the exploration of alternative schemes that offer stronger security and higher performance. In this work, we propose a dynamic multimedia encryption system based on a lightweight predator-prey simulation combined with chaotic dynamics. Our scheme extends the group chase-and-escape environment, in which prey and predators interact on a closed grid governed by predation and reproduction. Each prey is associated with a chaotic map that can be captured by predators in an unpredictable manner. As a result, the entropy of the system does not rely on a single map, but on the dynamical evolution of the chaotic-map population. When the prey population reaches a minimum threshold, a reproduction mechanism introduces new maps, ensuring continuous extinction and renewal while hindering any direct traceability of the chaotic sources. This process increases the variability and complexity of the system while maintaining a low computational cost. Experimental results show high randomness, strong information diffusion, and high key sensitivity, supporting the robustness of the proposed algorithm. In addition, our implementation achieves competitive performance, reaching encryption speeds of up to 1716 Mb/s. These results suggest that the proposed predator-prey chaos-based cipher is a promising alternative for high-throughput multimedia encryption and compressed-domain transmission.