Many of the dissolved ions are used by organisms in the ocean and are removed from the water...
The two ions that are present most often in seawater are chloride and sodium. These two make up over 90% of all dissolved ions in seawater.
The other ten percent are micronutrients that are also essential to life.
Most land animals have a skeleton not just to provide physical scaffolding to hang tissue on but because we need a store of calcium to mediate blood pH, something sea life doesn't require thanks to those minerals in the water. That's why you can have sharks which are mostly supported by cartilage with one set of bones: Their jaws.
The two ions that are present most often in seawater are chloride and sodium. These two make up over 90% of all dissolved ions in seawater.
The other ten percent are micronutrients that are also essential to life.
Most land animals have a skeleton not just to provide physical scaffolding to hang tissue on but because we need a store of calcium to mediate blood pH, something sea life doesn't require thanks to those minerals in the water. That's why you can have sharks which are mostly supported by cartilage with one set of bones: Their jaws.