“A growing number of creatures could disappear from the earth, with one-fifth of all vertebrates and as many as a third of all sharks and rays now facing the threat of extinction, according to a new survey assessing nearly 26,000 species across the globe. “In addition, forces such as habitat destruction, over-exploitation and invasive competitors move 52 species a category closer to extinction each year, according to the research, published online Tuesday by the journal Science …