Dive Dry with Dr. Bill

#475: California Moray: All Munching, No Mating

Landlubber's imaginations run wild with fear at the thought of the unknown down deep in Davy Jones' Locker. Some think they will be swallowed up whole by a great white shark if they so much as dip their tootsie (not to be confused with Dustin Hoffman's "Tootsie") into the water. Others see the gaping mouth and sharp, conical teeth of a moray and fear their fingers will be amputated. But in my experience both "the landlord" and the "eel" are not really threats unless one is really stupid or has the luck of someone who on Friday the 13th opens his umbrella before walking out the door, sees a black cat cross his path then steps on a crack and walks under a ladder into a large mirror and shatters it. Get the picture?

Morays have long, slender, muscular bodies that are light to dark brown or green in color and mottled with yellow. Divers usually see individuals in the two to three foot range, but they can reach up to five feet. The skin's surface lacks scales and is protected by a coating of yellow mucus. Their dorsal and anal fins are long and continuous, merging with the caudal or tail fin. Unlike most fish they have neither pectoral nor pelvic fins. The lack of these fins, smooth mucus coating and their body shape make it easier for the moray to swim through the nooks and crannies, crevices and holes in the reef... either in forward or reverse!

Morays appear vicious because their mouths open and close to allow the passage of oxygenated water into the gill cavity. These fish lack the operculum found on other species. Instead there is a small, dark, round opening on each side of the head. Morays have a pair of tubular nostrils that protrude from the head, one pair at the front of the snout and the other above or in front of the eyes. Of course these are not used to "breathe" but to chemically sense the water to locate prey.

Although our local California moray (Gymnothorax mordax) has eyes rimmed in blue like Sinatra, they have notoriously poor sight. Since they use their chemical senses to hunt prey, they usually come out at night to munch on fish, sea urchins, octopus, shellfish and crustaceans including crabs, shrimp and lobster. I'd be happy to order a cioppino or bouillabaisse created from such tasty delicacies any day! However, on my night dives I've noticed that they seem to be very poor hunters. Many a blacksmith went home to his family at night after a moray missed its target. Heck, I even saw one moray try to take a garibaldi with several half-hearted attempts. I thought perhaps it realized the stiff fine for taking one of our State salt water fish.

Since I've covered munching, it's time to detail the other "M" word, mating. Sad to say there isn't much to write home about with this species. Scientists believe the morays that live in southern California do not reproduce. Most species have both a minimum survival temperature, below which they perish, and a minimum reproductive temperature, below which they are... um, celibate. I think I need to check the thermostat on my furnace! So why do we even see them here year after year? Scientists believe morays further south in the warmer waters off Baja are able to spawn in open water, releasing their sperm and egg that develop after fertilization into a pelagic larval form known as a leptocephalus. These larvae may drift with the ocean currents for up to a year and are therefore quite capable of reaching our waters. This dispersal may be accentuated when warm El Nino currents push further north than usual.

Now one way to spot morays even if their heads are not protruding from their holes is to look for the presence of the red rock cleaner shrimp, Lysmata californica, near crevices and holes in the rocky reef. These crustaceans, also known as lined or peppermint shrimp (at least to their close friends), have a mutualistic ecological relationship with the moray. In return for protection from the eel, the shrimp serve as cleaners removing dead skin, parasites and food particles from the moray. These rather brave critters may crawl right into the moray's mouth to remove excess food, pick at the nostrils or crush tiny copepod parasites with their claws before munching them down.

Until fairly recently it was believed that the only moray in our waters was the California species. However, back in October of 2003 diver Chris Menjou took pictures of another moray right here in the Casino Point Dive Park. Its coloration is quite different with white speckling on a background of black, and bright yellow eyes. This single individual was determined to be a specimen of the argus moray, Muraena argus. Chris' find represented the first time this species had been recorded north of Magdalena Bay in central Baja. It was thought to have come up here as a larval form during the 1997-98 El Nino.

I've now been diving off-and-on for 50 years, 42 of them with morays here in Catalina waters. Not once have I been bitten, or even threatened by one. In my experience their reputation is entirely unearned. However, be very careful when placing your hands in a hole to capture a lobster. Oh, and don't try to feed morays hot dogs with your bare fingers. They aren't on their menu, and one unlucky diver in Thailand lost a thumb to a nearsighted moray.

© 2011 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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California moray with gaping mouth open to breathe, red rock cleaner shrimp surrounding moray;
a shot of the copepod parasites by Kevin Lee and Chris Menjou's shot of the argus moray in Catalina's Dive Park.

This document maintained by Dr. Bill Bushing.
Material and images © 2011 Star Thrower Educational Multimedia