|Fearsome or fascinating? The California moray eel (Gymnothorax mordax) belongs to the family Muraenidae. It is often seen in its "classic" pose: head protruding from a rock crevice, mouth slowly opening and closing while displaying jagged teeth. They stare out with large, blue eyes, almost daring a diver to get closer while saying, "This is my corner of the reef!" They seem unafraid, sliding out of their lairs like undersea serpents to investigate diver's activity. When I started diving in California, my first encounter with a California moray brought back memories from Hollywood movies. The Deep, that 1970s underwater thriller, featured a giant, man-eating moray eel. I wondered if the California moray eel was as fearsome is its reputation.
What I've learned over the years is that the California moray is far from fearsome. They can grow to five feet long, but average only two-three feet. Like many other California marine fish, the moray is long lived... as long as 30 years. Little is known about their early life, but is commonly believed that even the smallest eels found are 15 or more years old. In 25 years of diving, I've only encountered one "fingerling" sized eel. Though I never saw its full length, it was no bigger around than my thumb!
Presumably due to cooler temperatures, the California moray is not believed to reproduce in southern California. Only eels living in warmer waters off the coast of Mexico mate and lay eggs that hatch into larvae called leptocehalus. Larvae drift with ocean currents for up to a year before settling and maturing into juvenile eels. Since moray eels do not migrate, northerly currents are the only route for leptocehalus to reach the California coast. Some even label the California moray in our local waters mere "visitors," living on our reefs but not reproducing.
Despite its snake-like body and lack of any fins, the California moray is a fish. Unlike other fish, the moray lacks the ability to use only its gills to draw in water. It must open and close its mouth, creating a current of water across its gills, to breathe. A moray has a modified lateral line, used to sense vibration, near the front part of its head. The California moray has poor eyesight, but a sharp sense of smell. Knowing all of this, that "classic" pose makes sense. Rather than daring anyone to come near, the moray is merely sensing what swims by while opening and closing its mouth.
The combination of poor eyesight, sharp sense of smell, and an interest in vibrations contributes to its "fearsome" reputation. Morays occasionally emerge from underwater holes to investigate activities such as spearfishing and lobster hunting, startling unsuspecting divers. In reality, the California moray is simply another fish looking for an easy meal.
Since they often hunt in tight crevices and cannot "suck" in prey like other predatory fishes, moray eels have evolved a fascinating way of capturing prey. In 2007, researchers discovered that the moray eel uses a secondary jaw to pull prey down into its throat. Yes, much like those hideous monsters from the Alien series of movies, moray eels have a second set of jaws. When the moray bites down on prey with its main jaws, the second set of jaws slides up from the back of the throat and grabs on, dragging the food in to be swallowed.
Despite their fearsome appearance and adaptations, the California moray actually has a symbiotic relationship with the red-rock shrimp (Lysmata californica). These tiny shrimp live with the eels and, instead of becoming an easy meal, carry out the typical cleaning service that many shrimp perform in exchange for protection from predators. The union of red-rock shrimp with the California moray is so common that I often locate eels by simply looking for dark crevices with red-rock shrimp hovering around the mouth.
California morays are most often found along the vertical crevices of large rock piles. I have found them alone, or in groups of two or more. They are great subjects for photographers since they seem fearless (or at least careless) around divers. They will readily eat the roe (eggs) out of a broken urchin or the leftovers from a cleaned scallop. As a scuba instructor, I used to delight new students by feeding urchin to eels during open water dives. Students quickly saw that the California moray was a timid and almost gentle feeder. But remember that poor eyesight! Sometimes a feeding moray has trouble telling the difference between food and a finger. Though it commands respect, I have always felt the California moray was better described as fascinating than fearsome.