VNS causes stimulation of the superior and recurrent laryngeal nerves and is associated with problems ranging from alteration of voice (66%), coughing (45%), pharyngitis (35%) and throat pain (28%) and hoarseness (very common) to frank laryngeal muscle spasm and upper airway obstruction (rare).
The giant manta is commonly found offshore, while the reef manta, as its name suggests, is found inshore near coral and rocky reefs. Manta rays live in the open ocean, swimming continuously through the water column instead of resting on the sea floor like other rays. Although much of their time is spent near the surface, they have been known to dive to depths of 100 feet.
2. Mainly large sharks, but in Hawaii the Manta Rays have adapted to the habitat by staying within 3 miles of the shoreline thereby, to some extent, limiting their exposure to predators (like deep water sharks e.g. Tiger Sharks, Hammerheads). Their unmatched maneuverability and speed makes them hard to prey on.