Seems pretty obvious: maximum surface area with minimum backpressure, the design becomes like "lungs" or "placenta" branching from "artery" down in steps to "bl

Seems pretty obvious: maximum surface area with minimum backpressure, the design becomes like "lungs" or "placenta" branching from "artery" down in steps to "blood vessels". It looks like some early jet turbine combustors. "Kidneys" and reverse osmosis cartridges OTOH appear to function for optimizing for different constraints involving liquids and pressure.