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Dive Dry with Dr. Bill

#363: Blind as Amore... Er, A Moray

Morays have the largely unearned reputation of being dangerous. Their species name mordax does mean "prone to bite." Sure, they look pretty threatening while resting in their holes with their mouths open, displaying lots of needle sharp teeth. Even I have to respect the fact that their fangs far outclass my fairly pronounced canines. However, all they are doing is trying to breathe, just like you and me. The mouths are open to allow oxygen-bearing water in over the gills. Although divers are often startled when they see these fish swimming out in the open, they pose no real danger. Of course if you are hunting lobster, I don't recommend sticking your hand into dark holes at night. Just wouldn't be prudent.

Regular readers are familiar with my focus on night diving the past two months. I can barely remember the last time I descended during daylight, despite visibility of up to 80 feet during that period. My nocturnal descents have been undertaken to film the carnage that occurs in our dive park after the sun goes down. Fish like blacksmith, garibaldi, sheephead and other wrasses seek shelter then so they can rest without getting gobbled up. Their prey, including plankton, snails and sea urchins can wander out at night with reasonable safety. However, their predators don't aim to give them a good night's sleep! Large lunker kelp bass and morays are out on the prowl at night, along with harbor seals, looking for a tasty midnight snack.

I have written of the carnage caused by the large kelp bass as they hunt the sheltering blacksmith, and kelp surfperch still out in open water after sunset. These predators appear to have fairly good eyesight and often spot their prey at a distance, then sneak up on them. Surprisingly, the prey species often does not bolt until the kelp bass' mouth is within easy reach of them. Were I in their shoes (er, fins), I'd be hightailing it a lot earlier! This makes me wonder if their night vision is as bad as mine, or if my video lights momentary blind the prey.

Morays are a different story. I have heard tales of their relatively poor vision, yet I've never seen one at my optometrist's office. After observing them attempting to feed at night, they do seem to lack 20/20 vision. Perhaps I should loan them my "fish eyes." I have observed a moray watch a blacksmith swim very close to it, then lunge out to grab it... and miss. In fact, I have watched this far more times than I have watched one achieve success, and return to its hole with a late night meal. Some of the strikes are so far off, it is obvious they see not much more than a blur, or perhaps have horrible depth perception. Perhaps this is the reason Dr. Milton Love of UCSB says morays hunt primarily using their sense of smell.

On my night dives, I visit six different morays that seem to have specific shelter holes. I almost always find the fish in the vicinity of them. My favorite is a moray whose home territory is at the base of the finger reef closest to the Jacques-Yves Cousteau memorial plaque. His hiding place is at the base of an alcove-like hole in the reef, and I usually find him with his head and upper body stretching up out of the hole. Many a time I've seen him with several blacksmith swimming above him. Eventually he senses the motion (or the smell?) and either slowly reaches up towards them, or lunges at them. Inevitably he misses.

I've even seen him try to grab a garibaldi... and miss again! Good thing, since it would cost him a $500 fine to take our state salt water fish! In fact, I've only seen this individual take one blacksmith over dozens of dives. I had to wonder how he survives with such a poor success rate. However, he must have a great personality as I've seen him cuddling in his other hiding place with a lovely lady. Well, lovely to another moray anyway. Obviously this individual is more successful at mating than munching. Unfortunately his shelter hole filled in with sand and rocks recently, perhaps due to a careless diver, and I have not seen him there.

A while back there was a video out on the Internet that further illustrated the moray's poor vision, and how that could endanger a human being. A dive master in Thailand liked to feed hotdogs to morays. Now this is stupid in several ways. First, hotdogs aren't even proper food for human beings thanks to the nitrates, nitrites and other preservatives in them. Why is it we think that wildlife can be fed hot dogs, Cheez Whiz, Wheat Thins, chocolate or even peas and corn? I've never seen a fish or a marine invertebrate order these off a menu underwater. Second, hotdogs look a lot like human fingers and thumbs. You can probably guess what the moray bit off when the hotdogs ran out!

© 2009 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM 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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The "emaciated" moray sheltering with his sweetie (and singing a karaoke duet), the same moray in his night
time hole reaching for and missing his dinner, and my gift to him to ensure greater feeding success.

This document maintained by Dr. Bill Bushing.
Material and images © 2009 Star Thrower Educational Multimedia