National Geographic : 1995 Dec
On its daily commute through the inlets and channels around the Yap Islands, a manta pauses over certain rocks and hangs, barely fluttering, to bal ance in the current. Suddenly wrasses about three inches long dart from the coral below and head for the manta (bottom). The creature then opens its enormous mouth, and a wrasse enters the white cave, picking be tween the gill arches that sup port the gills (left). I also watch a jack swim ming with a manta as it slowly unfurls its "horns," or cephalic fins (far left). The extended fins no longer resemble horns but have become soft and pli able. The jack appears to be riding the giant's invisible body wave like an underwater surfer. It picks at bits of loose manta skin or uses the bulk of its companion as cover before making quick raids into the reefs for prey. For mantas, being cleaned is more than just a soothing act of grooming; it may be critical to life itself. Excessive marine growth such as algae can start a chain reaction of infection that could ultimately lead to death. Sometimes manta rays will leap entirely out of the water, possibly to clear them selves of parasites. Adult mantas face few natu ral predators: perhaps only large sharks and killer whales.