Why does the membrane of a tube worm stop salt for getting into its body?

The membrane of a tube worm is selectively permeable, meaning it allows certain substances to pass while blocking others. This is primarily due to the lipid bilayer structure of the membrane and the presence of specialized proteins that can recognize and transport specific ions and molecules. In the case of salt, the worm's membrane prevents excessive sodium and chloride ions from entering, helping to maintain osmotic balance and protect its internal environment from the high salinity of seawater. This adaptation is crucial for the tube worm's survival in marine habitats.