Meet the Mighty Wrasse
Published August 24, 2015
Winding patterns, watchful eyes and a mysterious bump on its head aren’t this reef-dwelling behemoth’s only oddities.
The first thing you notice is a set of bright-blue bulbous lips. A stark-white roving eye wanders into view before your focus shifts to the large lump jutting from the humphead wrasse’s forehead.
Ornate patterns adorn this fish’s shimmering blue-green skin, and if all of that’s not enough to divert your attention, its size alone is likely to catch your eye.
The humphead wrasse is what some might call a charismatic megafauna, a species with widespread appeal. And once you’ve seen him, you’d have a difficult time arguing otherwise. He’s one of the heftiest reef fish, and distinct features set him apart from the crowd.
Father of Fishes
Tangaroa, or Tang for short, is a humphead wrasse you can see in the National Aquarium’s Blacktip Reef exhibit.
A common name for the humhead wrasse is the Maori wrasse, most likely because the markings are similar of the Maori, an indigenous Polynesian group in New Zealand where the wrasse is found. Tangaroa is the Maori god of the sea and father of fishes, so the name was a natural fit.
The wrasse’s other common name, humphead, is a nod to one of its most defining features: the bump on its head. Scientists don’t know the exact reason males grow this protrusion, but they posit it is to attract mates.
A Taste for Danger
Humphead wrasses happen to be one of the few species that can feed on toxic animals, such as the crown-of-thorns sea star, which makes them important predators in a reef environment. Crown-of-thorns sea stars prey on coral, and the humphead wrasse helps keep their population in check, ensuring the ecosystem stays in equilibrium.
The female wrasse is easily distinguished from the male, differing in pattern, color and size. Juveniles are small and almost white, turning a burnt sienna as they age. Two distinctive dark lines radiate from their eyes.
All humphead wrasses start out this way, because they’re all born females. Humphead wrasses are protogynous hermaphrodites, meaning that as they grow, some transition from female to male. And in the world of wrasses, that’s actually pretty common.
It’s true for other fish as well, but scientists aren’t sure what environmental cues trigger that transformation for the humphead wrasse. For some other species, the female is the terminal developer. Clownfish, for example, begin life as males with some individuals later transitioning to female.