Dive Dry with Dr. Bill

#342: Working on My Night Moves

I rarely do night dives here in our cool temperate waters. In the past it was due to two things. First, I used to carry all my dive gear on a hand cart and it was a LONG and cold walk up the hill to my house after a dive. Second, night is the time when one should be cuddling up with their sweetie, or out dancing close and slow. Since I now have the Dr. Bill Mobile and have no one to do any cuddling with, I no longer have any excuse not to!

Last weekend I decided I would do my first night dive in the park in several years. The last time was with my nephew David. During our dive he kept pointing his dive light out towards the deep. When we got back to shore, I asked why. He responded that he was looking for the great white sharks. He'll soon be in South Africa cage diving with them (can I carry your dive gear?). I thought it was well past time to do another dive to film some footage for my upcoming DVD on the damsels of southern California (the fishy kind mind you, not the lovely lady-go divers).

I met Elena Rodriguez and her class from Pacific Wilderness at the park about 7:00 pm. There was a wedding party having their pictures taken by the stairs, which I found unusual. I just hope the bug the groom caught wasn't contagious! I set up my gear but, as usual, I got to talking with other dive instructors I knew as Elena descended the stairs with her class. I finally followed, but ended up solo because I had no idea which group of lights they were.

As I headed out towards the Cousteau memorial, I sensed something coming in from behind and to the left. I looked up in time to see a giant sea bass swimming past. When I turned to film it, the beam from my video lights hit its body and it took off. A short time later I saw another giant sea bass. Very cool... my first ones in the park this season, and the first I've ever seen on a night dive.

My mission on this dive was to film the nocturnal critters. As darkness falls, some like the blacksmith and sheephead retreat into shelter holes to sleep. Here they are safe from their predators and can get some rest for the next day's "munching" and "mating." With the sheephead safe in their crevices, their prey such as black sea urchins can come out in the open to forage. Lobster also appear outside their holes for a night of munching, making it far easier to film them. Horn sharks wander out to feed after sleeping in their caves during the day. The five I saw were still a bit drowsy and not yet out of their shelter holes. As I filmed one resting on the bottom, I noticed a moray swim behind it, and followed the moray with my camera as it went looking for blacksmith to crunch on.

The blacksmith, the closest local damsel relatives of the garibaldi, were just beginning to settle down for the night. I had an opportunity to film one's hostile behavior towards another blacksmith who tried to enter its shelter holes. These may have been males defending their hidden nests from other blacksmith, as I also saw a number of pairs cuddling together (sigh). Yes, blacksmith males get stuck with the child rearing duties just like their more colorful cousins, the garibaldi.

Speaking of garibaldi, I had been told by another diver on Friday that garibaldi could reverse gender several times in their life. I had never heard that, and questioned it although I knew their relatives (including Nemo, the clownfish) could. I researched the Internet and found several web sites that stated this, including Wikipedia. However, they were all derivative sites using the Wikipedia information. None of the scientific papers I read mentioned this. I decided it was time to contact Dr. Paul Sikkel, who did his PhD research on the garibaldi out at Two Harbors a few decades ago. Paul confirmed that this was not true, as did Dr. Milton Love... so yet another example of why you can't always trust the Internet (especially my site!).

My most significant observations on this night dive focused on the garibaldi. The first thing I noticed was that the males looked rather lethargic at night compared to their usual high levels of aggressiveness when they defend their nests from egg predators (or divers) during the day. In fact, they looked like they were napping just like their blacksmith brothers and sisters. None of them attempted to defend their nests as I filmed. They just looked at me, seeming to say "whatever" (in garibaldi language, of course). I e-mailed Paul Sikkel again the next morning and he confirmed that they do not actively defend the nests at night, but try to get a little shuteye.

The other observation that intrigued me was when I filmed a male which I thought was eating the older eggs in his own nest. Now males are known to do this with older eggs to create a nest that looks fresher and more enticing to females wanting to lay new clutches. Females will also eat the eggs laid in the nests, although I believe they eat those other females have laid rather than their own. When I edited the footage Sunday morning, I saw that the male was actually blowing streams of water onto the eggs, probably to pass oxygen-rich water over them. I was surprised to see and film this. It would be much more efficient to fan the eggs with their pectoral fins, which is the usual method for older egg clutches. Once again, Paul confirmed he had observed this as well. The footage I took will be quite useful in my "Damsels of Southern California DVD."

I thoroughly enjoyed this night dive, and the camaraderie of a number of instructor friends and their classes. After about 1,200 dives in the dive park alone this decade, it opened new perspectives on my familiar surroundings. Now that I have no excuse not to dive after dark, I think I'll be doing a lot more of it this summer. Oh, and David... not a single great white shark that night. You'll have to send me the pictures of the ones you see from the cage off Capetown, South Africa. I'm so jealous!

© 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!

Moray swimming behind horn shark in cave, lobbie or "bug" out in the open (and out of season);
sleepy male garibaldi making no effort to defend his nest blacksmith preventing
another from entering its shelter.

This document maintained by Dr. Bill Bushing.
Material and images © 2008 Star Thrower Educational Multimedia