In a previous column I left you waiting in great anticipation for the completion of my tale about my dive buddy Gary Garibaldi's love life. Good thing you weren't waiting for my story as it would be a very long wait! I had written about the male garibaldi's gardening efforts to create a nest full of red algae, and then his advertising attempts to entice young ladies into it by swimming in circles, known as dipping. If he is successful, she swims into the nest and lays a portion of her eggs there while the male literally goes bananas. He darts in and spreads his milt to fertilize them, then usually exits and watches over her. He repeats this process as she lays more eggs.
The tiny eggs are only a silly millimeter by two, less than 1/10th of an inch and barely detected even by my high definition camera (and certainly not by my low definition eyes). They adhere to the nest thanks to tiny threads. It is easy to tell when fresh eggs have been laid in a male's nest due to their bright yellow to orange color. As they develop, the eggs turn a greenish-gray.
More than one female will lay eggs in a male's nest. However, the subsequent females may inspect a nest with greater care than the initial mate did. She apparently assess the age of the eggs already in the nest. If they are still yellow in color, she may be more receptive than if they are older and greenish-gray. There is a good reason for this as eggs in different stages of development need different care. If she really likes the nest and its owner, but all the eggs are older, she may lay hers in a different part of the nest so they are treated differently according to the Dr. Spock of Garibaldi baby care.
Males are known to munch on a bunch of the eggs in his nest if they are older, leaving patches of red visible. It is believed he eats his potential progeny to make the nest appear more attractive to females who visit it. This is known as filial cannibalism. I often see females attempt to take bites from the existing egg masses in a nest, but they are immediately driven off by the male when this happens. He begins nipping her on the tail and making his clicking sound. Apparently that low frequency sound serves both to attract the ladies into the nest, and to drive them out. When I serenade the ladies, it usually just drives them away.
I mentioned the fresh yellow eggs and the more developed greenish-gray ones require different types of care by the male. Eggs need oxygen just like juvenile and adult fish. To ensure that, the male fans a nest containing the fresher yellow eggs with his entire body during the rapid early stages of embryo development. Older eggs are usually fanned with just the male's pectoral fins. At night I've even seen males blowing water on the eggs with their mouths, a behavior later confirmed by communication with other scientists.
The actual time to hatch depends on water temperature, with higher temperature favoring faster development. Hatching occurs in the evening, within a few hours of sunset. I'll have to be more observant on my night dives this month so I can film it! Newly hatched larvae are attracted to light and swim towards the surface. I wonder if a full moon aids in this, although not all broods would hatch during this phase. The larvae are swept away by the currents and develop initially while drifting in the plankton, before they settle near their new homes between July and November. The young are largely iridescent blue with patches of orange, with the blue gradually disappearing as they age. It is said the different coloration prevents aggression towards the young, but I've seen a number of adults chase the youngsters away. Probably can't blame them, although I'd never chase my granddaughter Allison away (and never did my son Kevin either)!
The male will defend the nest from any potential egg predators during the two to three weeks each clutch of eggs takes to mature and hatch. Back in the 1970s Jean-Michel Cousteau showed me how a garibaldi will remove variable starfish from their nest so they don't eat the eggs. The male picks up the starfish by one of its arms, carries it away from the nest and drops it. I placed these sea stars in the nest of one garibaldi and watched as he took it further and further away with each appearance. You might think this doesn't happen without human intervention, but I've seen and filmed garibaldi removing these stars when there are no other divers in the vicinity.
I spend a good part of the summer diving after dark to film the changes in species and behavior seen during "the night shift." It certainly is as different as night and day! A few years ago I was surprised to see that the males do not aggressively defend their nests at night. I could approach very close and they would usually remain nearby in a hiding place. I don't remember ever seeing them fan their eggs at night either, although I'll keep a closer watch this summer to see if I've just missed it before. Hmmm... maybe my increased night diving during summer is one reason why I don't have anything to write home about concerning my own love life!
If you find the amorous exploits of the garibaldi to be exciting, I hope you will help support the efforts by diving legend Bob Meistrell of Dive N' Surf and Body Glove, the crew at SCUBA Luv and myself to place a web cam in the dive park so you can watch their behavior from the comfort of your easy chair with your laptop in front of you. Now that's what I call "diving dry!" No cold water or wetsuit required (unless it is by Body Glove).
© 2012 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. You can also watch these episodes in iPod format on YouTube through my channel there (drbillbushing). 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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Gary and Geraldine doing "the wild thing;" fresh yellow eggs centered in a red nest and Gary making his nest
more attractive by taking bites out of the older egg patches to reveal the underlying red.
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Dr. Bill Bushing.
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