More often than not, I dont pay much attention to individual goatfish. Seeing large schools of yellow goatfish at a place like Snapper Ledge always makes for a great dive.
Photographing a spotted goatfish at night with its bright colors on display is also a favorite goatfish observation.
But a goatfish here and there with its barbels flailing away creating a cloud of sand and debris is not my preferred set up for a clear image.
My dismay with their debris cloud, however, is misplaced. Goatfish have an important role on the reef, and undergo a metamorphosis that transpires in a matter of hours, not days or weeks.
Their sediment cloud creation activity actually feeds many other fish. According to a study by a group of scientists in Brazil, spotted goatfish have more groupies than any other fish. They counted seventeen species that follow goatfish around to benefit from their barbel-based foraging technique.
Classified as a nuclear species, goatfish truly play a leadership role. Other species are attracted to the substratum-disturbing foraging. And when several goatfish are involved in the fray, the groupies increase in number and diversity.
Single goatfish usually have up to three follower species at a time. Goatfish groups attract up to six follower species. These are primarily benthic carnivores. When critical mass is reached, the crowd includes herbivores that swoop in for the algae present in the cloud. There were no documented instances of herbivores following a single nuclear goatfish - they stated it only occurred in a group setting of eight or more goatfish.
The top five followers in the Brazilian study were puddingwife, coney, yellow jack, horse-eye jack and red parrotfish. I dont ever recall (basically because I never really paid that much attention) seeing that particular mix of species hanging out with a goatfish. In the Keys, I have seen them with yellowhead wrasse quite often. Ill pay more attention now if it helps me get closer to a puddingwife. In my experience, they are typically shy and difficult to approach, but the colors are terrific if you can get close enough to illuminate them.
I have zeroed in on a single spotted goatfish foraging, accompanied by a yellowhead wrasse. There was a little bit of current, so the cloud cleared rather quickly and I was able to get some good shots. While the goatfish was sticking its barbels and head in the soft bottom, the wrasse just hung around, and every now and then popped in for a morsel. There is always entertainment on the reef, wherever you look.
Even more interesting was the statement that while many of the follower species eat the same food, the goatfish dont seem to mind, and the followers and the goatfish dont fight over the prey items raised in the cloud.
The foraging also has anti-predatory benefits to the follower. As we know, there is safety in numbers. Using the cloud as a smoke screen for potential predators while gorging on the smorgasbord works pretty well. Life is good on the reef, just find a goatfish, and get protected and fed.
Spotted goatfish are far and away the stars of the nuclear group, accounting for 50 percent of the nuclear/follower activity out of the thirty nuclear species studied.
Go to this link to see the research: http://rd.springer.com/article/10.1007/s10641-006-9123-3
Dr. Mark McCormick of James Cook University, Australia, has studied the goatfish metamorphosis extensively. During the change from a pelagic larvae to a juvenile goatfish, the eyes change dramatically and the barbels sprout.
While in its pelagic larval form, goatfish school and stay in the top twenty feet of the water column, feeding on plankton. Their eyes have two layers of sensory cone cells for maximum efficiency, since they feed by sight. With the change to a juvenile, these layers merge into one, and their vision adjusts to life as a benthic carnivore.
The barbels fully develop upon settlement. In the larval stage, the barbels are tucked up under the chin and quite small. The metamorphosis comes when they settle on the reef. The barbels grow over fifty percent in six to twelve hours. A lot of that change is accounted for by a tremendous increase in the size of taste buds.
At that point, the barbels morph to the size they need to be to become fully functional. The development of barbels is one of the most rapid transformations on the reef. Its much faster than the migration of the eye in a flounder or the development of lateral lines in other species. As its vision changes to acclimate to new lighting conditions, the barbels become the main feeding mechanism of the juvenile as it settles in its benthic environment.
The size of the barbels can vary depending on the feeding behavior during the larval stage and the time of metamorphosis.
The barbels consist of a layer of taste buds wrapped around a central core of bone and cartilage.
In an experiment studying the metamorphosis from larvae to juvenile, the importance of the new barbel was demonstrated by cauterizing the nose tissues. With no sense of smell, the goatfish continued to forage and eat regularly. The other side of the experiment (barbels removed), left the goatfish essentially helpless to feed.
You can see one of Dr. McCormicks research papers here: http://link.springer.com/article/10.1007/BF00004634
The next time I see a goatfish raising a cloud Ill have a different perspective. I guess Im changing, too.
Tim Grollimund is a freelance photographer and PADI divemaster based in Key Largo. He can be reached at firstname.lastname@example.org or through his web site at www.timgimages.com. Tim is actively involved with the Coral Restoration Foundation and the Aquarius Foundation.