Shark Blood Changes All The Time

Sharks change their blood volume depending on the saltiness of the water they're swimming in, according to new research. So sharks must continuously regulate their blood and other body-fluid volumes as water salinity changes. The paper, in the latest issue of the journal Comparative Biochemistry and Physiology, provides one of the most extensive looks at this phenomenon, and points out how massive ice melt triggered by warming could spell trouble for sharks. Although sharks absorb water through their gills, they may also drink seawater and expel shark urine to keep their systems in sync with their environment...