Marine Osmoregulation — Salt & Water Balance in Fish (2D)

This 2D companion to the 3D osmoregulation simulator cuts straight through a fish at the gill membrane so the actual water and ion traffic is easier to read at a glance. Pick a marine bony fish, a freshwater bony fish, or a urea-retaining shark, tune ambient salinity and temperature, and watch blue water-molecule particles cross the membrane in the direction — and at the speed — the real van 't Hoff osmotic-gradient model dictates, gold ion-pump particles work against that gradient whenever active transport is switched on, and a light-blue drinking stream appears for a marine fish compensating for water loss. A scrolling three-channel strip chart tracks the live osmotic gradient, net water flux and ATP cost underneath, and the cross-section itself can be panned and zoomed for a closer look at the membrane.