GILL. Found in many aquatic life forms, an organ which allows them to extract oxygen from water and pump out carbon dioxyde. Gills have the same function as lungs, but a fundamentally opposed structure. Gills are not dead-ended breath sacks like we have, but filtering pathways through which water runs. Fish cannot stay immobile while breathing: they need to keep water and blood flowing in the right direction for their gills to work. Keep moving, learn to swim, keep moving, keep breathing. Zoologists call gills branchiæ, imported from greek through latin: in ancient Greek, βρόγχος meant throat, in the sense of duct. Did the Greek think we had gills, or that fish had lungs ? In the game World of Warcraft is a species called Murlocs, half-human half-piranha in shape. They can breathe underwater, without gills. How ? Although it doesn’t prove that Murlocs aren’t real, it does prove we still have much to learn about the way fish breathe.