Landlubbers may not realize it, but this is the time of year when my frequent dive buddy and our state salt water fish, Gary Garibaldi (Hypsypops rubicundus) is feeling his oats. By the time he and his male friends reach the ripe old age of three to six years, they are ready to perform the duties of all individuals regardless of species... to ensure the continuity of their kind! Yes, I'm referring to the "mating" part of Munching and Mating. But don't worry mothers, your kids are safe today. I'm not going to go into the gory details.
Garibaldi are members of the damsel fish family. To me that's almost like naming a boy "Sue" (with apologies to Johnny Cash). And it seems to have had the same effect. Despite their "girlie" family name, damsels are often rather pugnacious and will fight off much larger species if they intrude into their territory. This is especially true during mating season. Many an innocent diver has wandered too close to a male's brood and been charged relentlessly as the garibaldi tries to drive them off. I've had them grab my camera and shake it, bite my fingers til they bled and at least one diver I know had her ear bitten. Imagine the hormones coursing through their orange bodies that drive them to risk life and limb (er, fin) against much larger critters!
When water temperature reaches a balmy 59 F, "the urge" strikes Gary and he will begin the process of creating a nest for his young 'uns by turning into a gardener. Using his mouth, all species of algae and marine life with the exception of a few types of red algae are carefully weeded out of a somewhat circular patch on the rock that may be a foot across... or five to six feet in diameter for those on steroids. Since red light is filtered out in the upper layers of the water column, this nest often appears like a dark patch on the reef unless it is very sunny. When a diver turns their lights on, the bright red color stands out. It does offer a fair degree of contrast between the other brown and green algae on the rocks.
The garibaldi tends this nest religiously. Foreign objects that fall onto it are quickly removed by the male and transported away from the nest. This includes potential egg predators as well. Back in the 70s Jean-Michel Cousteau showed me that when a variable starfish comes close to the red bullseye, the garibaldi will pick it up by one of its arms using its mouth and banish it. One day I was feeling especially playful, and kept placing a variable star on the nest of one poor male. Each time he would pick it up and carry it off, taking it farther and farther away. The last time the garibaldi dropped it in midwater about 20 yards away. For those who feel this may be a contrived behavior, I have actually seen these fish carrying these sea stars off in their mouths when no other divers have been in the dive park.
Defense of the nest intensifies when the male actually entices a female into his lair, and gets her to deposit her eggs there. He does this by swimming in tight circles or ovals near the nest, making a clicking noise as he darts about. This is referred to as dipping. If the lady passing by is suitably impressed, she comes over to check out his "garden." If she finds it suitable, she will lay her eggs within it and the male will dart in over them to spread his milt. One particularly virile male seemed to have a different lady in his nest each time I passed by. On one occasion, I dropped to my knees and filmed the mating. I thought I might have taken 7-8 min of footage, but when I got back home I had nearly 15 min of "action." And that was only the portion of the tryst where I had the camera rolling!
At some point the male usually drives the female off, sometimes by biting her tail. Then he resumes his act, trying to entice more ladies into his nest. That's right! These damsels must have read the Book of Mormon and practice polygamy (which apparently is not illegal down under... and I'm not talking about Australia!). They may engage in a number of such breeding cycles during the course of their mating season. Newly laid eggs are a bright yellow, contrasting nicely with the red algae. A single female may lay as many as 15,-18,000 of them. Females will sometimes take big mouthfuls of the eggs of their predecessors, which causes the male to forcefully drive them off. Woman can be so jealous! But we love them, right Gary?
Once eggs are deposited in the nest, the male aggressively cares for and defends them. He weeds the nest, removes potential egg predators from it and keeps other fish (and divers) at bay. As the eggs develop, they turn a greenish gray. Nests will often contain eggs in various stages of development due to the multiple trysts a male engages in over the 5-10 day breeding period. You may see both yellow and gray eggs in a single nest. Eggs in different stages of development require slightly different care by the stay-at-home dad. New, yellow eggs are aerated by fanning the nest with the entire body and tail fin. More mature gray eggs are fanned with the fish's pectoral fins. Apparently females understand this and new potential mates are discouraged when they see only older eggs in a gray nest.
Gary has come up with a "brilliant" strategy to ensure additional romantic encounters. If his nest is full of maturing gray eggs, he will occasionally gulp down a few mouthfuls of the older ones. This exposes the red color of the underlying nest, making it more attractive for his new lady friends. Scientists refer to this as filial cannibalism. As a scientist myself, I must admit that I do not understand why a father would destroy entire batches of his potential offspring just to ensure a new "generation" is created. Just what is the evolutionary advantage of starting the process all over, entailing more days of hard work tending them. Could it be that their hormones just get the better of the boys and they can't help themselves?
NOTE: My Uwatec Tec 2G and Dive Rite Nitek Duo dive computers are still among the "missing." I am offering a reward for their safe return, no questions asked. Or you may turn them in to one of the dive shops in town. Replacing them will be a big "hit" out of my divebum budget.
© 2011 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. 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 with his newly weeded garden... er nest, and watching one of his many mates lay her eggs;
yellow eggs in nest with bite marks (perhaps from jealous females), and older gray eggs
in nest with bite marks (most likely by Gary himself due to an overdose of hormones).
This document maintained by
Dr. Bill Bushing.
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