The largest species of ray in the world, these magnificent beasts (often called "devilfish") can grow as large as 25 feet across and have the largest brain-to-body ratio of all sharks, rays and skates. They are gigantic, smart and probably the last thing you want to see emerge from the deep while you're swimming in clear tropical waters on vacation.
In reality, though, manta rays are gentle giants. Like many other mammoth fish in the sea, they are filter feeders that eat the smallest of prey. Unlike stingrays, manta rays don't have a stinger, so divers have nothing to fear.