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Dive Dry with Dr. Bill #363:


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#1 drbill

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Posted 21 November 2009 - 12:22 PM

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!

Posted Image

Image caption: 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.

#2 Landlocked Dive Nut

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Posted 21 November 2009 - 01:54 PM

Another informative piece, delivered with your signature tongue-in-cheek humor! Thanks, Dr. Bill.

Bad eyesight or not, I'm still going to keep my fingers tucked when I'm around a moray. You never know which ones have been training on those hotdogs! :cool2:
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#3 dustbowl diver

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Posted 22 November 2009 - 07:41 AM

Thanks Dr B for sharing this read!!
"Yesterday's gone, tomorrow never knows, today will never be the same again!"-Jibe

#4 WreckWench

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Posted 22 November 2009 - 10:33 AM

Dr Bill I sooooooooooooo did not know any of that! How cool and very strange you have observed them to be bad hunters. I have been more fascinated with eels since my wedding band is a beautiful moray eel head to tail with just enough gap to allow the ring to separate in the event of being caught in machinery. It seems I am now drawn to these beautiful animals and can watch them for hours...(well at least 10+ minutes until the last of the group is so far ahead of me that I have to move to catch up with them!) :birthday:

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#5 drbill

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Posted 22 November 2009 - 10:46 AM

Another interesting fact about the California moray "common" here is that some scientists believe they are not capable of reproducing in our cooler waters. They believe that the larvae of morays from Baja California drift up into our region during warm water episodes, and are able to survive in our temperatures but not reproduce successfully. That could explain why we see what appear to be wide fluctuations in their populations.

#6 WreckWench

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Posted 22 November 2009 - 11:06 AM

Another interesting fact about the California moray "common" here is that some scientists believe they are not capable of reproducing in our cooler waters. They believe that the larvae of morays from Baja California drift up into our region during warm water episodes, and are able to survive in our temperatures but not reproduce successfully. That could explain why we see what appear to be wide fluctuations in their populations.


Very cool...er chilly eh???

That is also wild! I was wondering how you had them in the first place. But they certainly have not lost the instinct to 'mate'...just can't capitalize on it eh?

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#7 drbill

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Posted 23 November 2009 - 10:48 AM

That is also wild! I was wondering how you had them in the first place. But they certainly have not lost the instinct to 'mate'...just can't capitalize on it eh?


Yep, I think I have the same problem... tee hee

#8 WreckWench

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Posted 23 November 2009 - 11:04 AM

That is also wild! I was wondering how you had them in the first place. But they certainly have not lost the instinct to 'mate'...just can't capitalize on it eh?


Yep, I think I have the same problem... tee hee


Oh DrBill...you are too funny and its a good thing I'm already taken! :lmao:

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#9 gcbryan

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Posted 24 November 2009 - 12:44 PM

Interesting article as usual Bill! Our Wolf Eels have the same problem and they are not even true eels. I try not to feed the wildlife but I have feed a few both out in the wild and in the Seattle Aquarium. It's definitely a good idea to let go of the food a few seconds before they take it as their aim and eyesight isn't what I'd prefer it to be.

Maybe it's just depth perception due to the spacing of the eyes? In any event they seem to share this issue with your Morays.

#10 drbill

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Posted 25 November 2009 - 10:15 AM

We have wolfies down here, too, but they are one species I've never seen. Your comment about the placement of the eyes on the head may indeed be the reason for their poor depth perception.




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