Few animals make the move from saltwater to freshwater habitats; a slew of physiological and ecological barriers limits this. And for sharks, it's because. read more
Of the more than 1,000 species of Elasmobranchii (sharks, rays, and skates), only 5 percent can live in freshwater, and most of them do so part-time only. By comparison, Science explains, about 40 percent of bony fish (from goldfish to rainbow trout) live in freshwater. read more