Answer:
Specially developed kidneys, gills, and body functions help prevent the water from bringing harmful salts into the body, this can be used through process of osmosis. Marine creatures need to be able to absorb dissolved oxygen from the water, with which it uses to release the energy from food.
Step-by-step explanation:
Estuarine plants and animals need to be able to live in conditions of different levels of salinity, oxygen, and water level. Take the mangrove tree for instance, it's a plant that can grow in salty water. It's adaptation is it has an ultra filtration system in its roots. Other species may have specific adaption's to filter out salt, or maybe use the salt as nutrients. Others may need tough skin in order to survive the pressure of ocean depths.