What is the salinity of water that shark live in?

Sharks live in a wide variety of environments, from freshwater rivers to the deepest parts of the ocean. This means there's no single "salinity" that applies to all sharks. Here's a breakdown:

* Saltwater Sharks: The vast majority of shark species live in saltwater oceans, which have a salinity level of around 35 parts per thousand (ppt). This is considered "normal" ocean salinity.

* Freshwater Sharks: Some shark species have adapted to live in freshwater rivers and lakes. These sharks have a lower internal salt concentration than saltwater sharks and have evolved mechanisms to deal with the lower salinity. Freshwater salinity is typically less than 1 ppt.

* Brackish Water Sharks: A few shark species inhabit brackish water, which is a mix of freshwater and saltwater. This type of water has a salinity level between 1 and 35 ppt.

So, while there's no one-size-fits-all answer, most sharks live in saltwater with a salinity of around 35 ppt.