FaunaTag is a biologging platform designed to measure the behavior, acoustic environment, and physiology of free-swimming whales and dolphins. The tag integrates motion sensors, hydrophones, and environmental sensors to record movement, underwater sound, and habitat conditions experienced by the animal. FaunaTag tags attach using non-invasive suction cups and are designed for short-term deployments that collect high-resolution data while minimizing disturbance. We're using the FaunaTag v2 to study how cetaceans behave, communicate, and respond to environmental and human pressures such as ocean noise. Ongoing development of FaunaTag v3 adds multi-channel acoustic recording and next-gen physiological sensors.