There might be a tendency to overlook the saddle wrasse (thalassoma duperrey) simply because it is one of the most commonly seen fish swimming over the reef. However, like many other wrasse species, it provides an interesting study in coloration changes, mating habits and behaviors.

This endemic fish, known as hinalea lau-wili in Hawaiian, shares a unique swimming pattern that is a characteristic feature of the wrasse family. The saddle wrasse swims by flapping its pectoral fins up and down like a bird, giving it the appearance of flying through water. This form of swimming is called labriform locomotion, named after the labridae/wrasse family. They are constantly on the move, scanning the reef as they swim high, low, back and forth. It takes a steady hand and a great deal of patience for the underwater photographer to snap a shot of this wrasse.

Saddle wrasses are carnivorous fish, feeding primarily on benthic, or ocean floor, animals. Crustaceans are a favorite meal along with mollusks, urchins, brittle stars and other invertebrates. They are opportunistic feeders and will consume whatever becomes available as they search for prey. Saddle wrasses are specially equipped with canine teeth and pharyngeal bones near their gills, which help to crush the shells of prey. During the juvenile stage, saddle wrasses can behave like cleaner wrasses, providing cleaning services to larger fish while feeding on their parasites.

These wrasses inhabit shallow coastal areas to outer reefs, 5 to 30 meters (16 to 98 feet) deep, and prefer areas with rocks, rubble, and plenty of pukas (holes) to hide in. At night, saddle wrasses are often found resting on sandy substrate as they will burrow into the sand if the need to hide arises. Despite being collected for the home aquarium trade, populations are steady. During surveys of various reef habitats, saddle wrasses were found to be present in 95-100 percent of the locations surveyed, which is a testament to their far reaching presence in Hawaii.

Adult saddle wrasses reach lengths of up to 11 inches. During the juvenile stage, saddle wrasses bear no resemblance to their adult counterparts as they lack the distinct saddle and blue-green coloration of an adult. Juveniles have a white stripe from the tip of their snout to the base of their tail, a dark band along their lateral line, and tan to orange coloration on the dorsal (top) and ventral (bottom) sides.

Although most saddle wrasses are born female, there are primary males (born male) and secondary males (females that transformed into males) whose coloration is similar but brighter than those of the initial phase females. Saddle wrasses exhibit protogynous hermaphroditism, which is a fancy way to say that they can transform from female to male. This process typically correlates with the needs within the social structure of their home range, depending on the presence of larger or smaller saddle wrasses in a given area. They will mate across overlapping home ranges rather than in harems, which may contribute to their stable populations. Therefore, the chances of continuing to see the common sight of this not-so-common fish are quite good.

Maui Ocean Center currently exhibits the saddle wrasse. Due to the constant rotation of animals back to the ocean, the presence of any specific animal cannot be guaranteed.

* Colleen Foster is director of education at 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.