Last month's article focused on sand: what it is and where it comes from. It is an interesting topic to know more about and is sure fun to think about when at the beach, ankle deep in the product of the parrotfish's hard work. The uhu, or parrotfish, is praised for being the proverbial sand factory, but it is worth mentioning that without one you may not have the other.
This family of primarily herbivorous fish when fully grown ranges in size from the 12-inch yellowbar parrotfish to the 28-inch ember parrotfish, the largest in Hawaii. The vibrant colors of the supermale (yes, that is what he is called) are stunning and their stocky figure makes them easy to spot.
Parrotfish live in harems so if you spot a vibrantly colored male, look at the fish close by. They will likely be the same shape but are smaller and noticeably less colorful. These are the females, initial phase males, and juveniles, which can be red, gray or a combination of both. Within each harem is a hierarchy and there is a dominant female.
All but the stareye parrotfish have fused teeth that form a beak perfect for scraping algae. When a parrotfish scrapes dead coral to get the algae growing on it, they clear an area for new, fresh coral growth.
KEOKI STENDER photo
When the supermale is eliminated from the group, the dominant female will undergo a transformation where she'll get larger and become vibrantly colored. She will change into a male capable of fertilizing the eggs of her now inherited harem. She will now be a supermale for the rest of his life! As amazing as that is, it is not the only interesting trait they have. Many species of parrotfish make a gelatinous cocoon each evening when they "go to bed." This cocoon could be a way to mask their scent from lurking predators like eels or could be a way to keep parasites from bothering them during rest.
All but the stareye parrotfish have fused teeth that form a beak perfect for scraping algae and in the case of some, like the bullethead, scraping for coral polyps. Excessive algae growth can blanket a healthy coral reef preventing any coral growth. Parrotfish, along with other reef fish families like surgeonfish, help keep algae from blanketing entire areas of the reef where they live. When a parrotfish scrapes dead coral to get the algae growing on it, they clear an area for new fresh coral growth. The sand that is ultimately created from this process provides refuge to other marine animals like garden eels and crabs, while others like the black sea cucumbers use it to cover their body as camouflage.
A study from the University of Hawaii reported that when a large parrotfish of 18 inches is left to graze, that single fish can produce about 700 pounds of sand in a year. In contrast, they reported that a single 12-inch fish will produce a mere 66 pounds in a year. This UH study also reported that traditionally it was common to see mature parrotfish that weighed 20 pounds but now we are considering 12 pounds as a large fish.
This is not an outcome that warms the hearts of anyone from snorkelers and divers to fishermen to conservationists. Hawaii is an impressive melting pot for human diversity that enriches everybody and because of this diversity there are many different viewpoints on what the ocean is and what to use it for.
The bottom line is that when you list everyone who uses the sand, from the fish and crabs to the sea turtles, monk seals and humans, you can begin to appreciate just how amazing and important the role of the parrotfish is.
* Erin Iberg is the community education manager at the Maui Ocean Center. "Ka Mo'olelo Moana," or "the Ocean Story," is a monthly column submitted by the Maui Ocean Center, which is open from 9 a.m. to 5 p.m. daily in Maalaea. For more information, call 270-7000.