For questions about the mechanical processes that allow organisms to live, including respiration, consumption, excretion. Focus on shapes of body parts and connections between parts.
Biomechanics are the processes (mechanics) by which biological organisms function. They includes some (but not all) of the essential life processes, including:
The study of these mechanics is biomechanology.
This tag should be used on questions about these processes, for example asking how one might viably alter the biomechanics of a species. Take care that your question is not pure biology, as it may be a better fit on the Biology Stack Exchange.