A marine sea star was mistakenly placed in freshwater. A few hours later, you find the sea star is dead. What is the most likely explanation for its death?

Osmosis and its role within molecules.
Osmosis is a process during which water moves from a lower concentrated region to a highly concentrated region through a partially permeable membrane. When there is a difference in osmolarity between two solutions, water will flow from hypoosomic solution to hypersoomic solution by osmosis. It is a passive process where energy is not required. If the cytoplasm is in a hypotonic solution, water molecules will enter the cell. The high uptake of water by the cell will cause it to swell and eventually burst. However, if the cell is found in a hypertonic
Sea star can adjust its osmotic pressure in its environment as they both have the same concentration of salt. The concentration of freshwater is higher than in the sea star. Freshwater is hypotonic to the sea star cells where dissolved salts are present. During osmosis, water molecules will enter the cells of the sea star thus increasing the osmotic pressure. This will lead to cell function disruption where essential organs are dehydrated and are unable to metabolize. Therefore, the sea star is considered as a poor osmoregulator as it cannot adapt to different level of salinity. Osmosis is important to regulate water equilibrium allowing nutrients to be absorbed and wastes to be removed from
Osmoregulators are able to control the movement of solutes whether it is internal or external. Osmoconformers do not have this ability and are isosmotic with their surroundings. Marine stars are stenohaline, animals who cannot withstand changes in the external osmolarity. So if a sea star has a sudden influx of water, the cells within will shrink or shrivel causing their organelles and cell membranes to be damaged and eventually die. Osmoconformers are not able to regulate solutes in their body in different concentration because of the permeability of their bodies and the absence of organs such as kidneys that allow them to produce urine in multiple solute