Toxic algae killing sharks, rays, crabs: "Like a horror movie for fish" / Fish use sharks as shields to ambush prey, study reveals / Cuttlefish ink has potential as natural repellent to keep sharks away from beaches / Surfboards with lights could deter shark attacks: "Invisibility cloak" / Tourist feared eaten by sharks in Indonesia after being swept out to sea / Protection of highly threatened sharks and rays inadequate, study finds