Hawaiian Marine Life Profiles: Fish

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Common Name:


Hawaiian Name:

kala lolo

Scientific Name:

Naso unicornis

Found in Exhibit:

Open Ocean

An old Hawaiian saying, "he kalai'a i'oi ka hi'u" (kala fish with a sharp tail) is used as a compliment to describe someone who can defend himself. Kala, meaning rough in Hawaiian, is the general Hawaiian name for surgeonfish, which have sandpaper-like skin. Kala also possess sharp, protective spines that can inflict deep wounds. The common name surgeonfish reflects the fact that these spines are 'sharp as a surgeon's scalpel'. The spines of the kala are modified scales and are used for defense from predators and also to ward off other fish that are competing for food. Some surgeonfish have spines that are brightly colored, or distinct from the body color, to serve as additional warning.

All members of the surgeonfish family (sometimes called tangs) have at least one spine located at the base of the tail, on each side of the body. In true surgeonfish, this spine is hinged and is generally folded into the body. Unicornfish are identified by two spines on each side, which permanently project from the body. Some unicornfish also have a horn-like projection extending from the top of the head, hence the common name. In one of the biggest mysteries on the coral reef, the function of the unicorn horn is still unknown.

Surgeonfish were very popular with the early Hawaiians, most likely because of their abundance near the shore. Most surgeonfish were desirous as a food source and the tough, scale-less skin was also used for the tops of small coconut-shell knee drums. The early Hawaiians captured kala in basket traps called hina'i, which were likely the earliest form of 'nets' used by the Hawaiians. Some of the hina'i were large enough to fit three adults. These woven baskets were weighted with a large stone and often baited every day for up to a week. Once the basket became a source of food for several fish, a special funnel-shaped top was added to the basket, which allowed entrance, but no exit for the fish.

Most surgeonfish are herbivores, eating algae off rocks, coral, sand, and even turtle shells, therefore surgeonfish are generally found in shallow water, where algae is most abundant. Some species of surgeonfish form schools during feeding. This is intended to overwhelm territorial fish, such as damselfish, that also feed on benthic algae. Because surgeonfish scrape hard objects for algae, their eyes are located high on the head with a low mouth, which probably reduces damage to the eyes during feeding.

Surgeonfish are as abundant around Hawaii's coral reefs today as they were in the days of the early Hawaiians. Though no longer considered a main food source, they are well known by snorkelers and divers, some for their vibrant colors, and the unicornfish with their almost human-like profiles. Though surgeonfish are not considered aggressive, their spines are very sharp and can cause deep cuts. Therefore, it is important for snorkelers and divers to avoid harassing these fish, which can act defensively.

PDF: unicornfish.pdf