In this episode of “Take a Minute to Relax” we’d like to introduce you to a beautiful creature that goes by the Hawaiian name of Humuhumunukunukuāpuaʻa, or Humu-Humu for short. Although this may sound nice, roughly translated it means “triggerfish with a snout like a pig”. Outside of Hawaii though, most people probably know this fish as a black bar, lagoon, or Picasso triggerfish, whilst scientists call it Rhinecanthus aculeatus.
Take a Minute LII: The look
Triggerfish are of the Balistidae family, which get their name from their dorsal locking spine, which they can not only use to deter predators or to “lock” themselves into holes, crevices, and other hiding spots but can also be used as a means to communicate. This fish has a very sleek, oval-shaped body that can reach a length of around 30cm. They can be found in the Indo-Pacific region, as well as the Red Sea. Within this range, the Picasso triggerfish, like many other triggerfish species, prefer shallow, coastal marine waters where coral reefs often occur. Here, they can find sections of the reef to shelter in and sandy areas to form their nests.
Triggerfish: Diet and locomotion
The Triggerfish family as a whole use their powerful jaws to their advantage, feeding on a variety of hard prey such as crustaceans and molluscs. Sea urchins and other echinoderms can also quite often find themselves on the menu of Rhinecanthus. Although there are some species that prefer softer prey such as small fish, while others are vegetarian, feeding primarily on algae and/or plankton. Triggerfish can often be observed, flapping away debris and squirting water onto the sand with their mouths This way they get to the prey that is hiding underneath. Also, they knock over sea urchins to get to their soft(er) bellies.
Most of the swimming is done by using waving motions in their dorsal and anal fins, rather than by flexing their whole body like many other fish, allowing it to move more precisely. Using these fin movements, Rhinecanthus aculeatus can move forwards, backwards or simply hover in place above the reef. This means that it can more easily back out of crevices than other unidirectional fish.
Picasso Triggerfish (Rhinecanthus aculeatus)
The Picasso trigger’s reproductive behaviour is just as complex and interesting as its colouration. Aggressive, territorial polygamist and caring, protective parent, Picasso triggerfish are hard to categorise. Males guard their territories vigorously against any intruders and spawn with all females residing in that territory. After spawning, when the egg masses are attached to sand, coral rubble or algae, both sexes protect the vulnerable eggs from predators. With powerful jaws and sharp teeth, Picasso triggerfish are formidable guardians and have been known to nip at divers who intrude on their territory. Not only do they use their dorsal spine to let intruders know they’re not welcome, these fish take it one step further and use “grunting” noises to communicate with each other. This way they can alert their neighbours of dangerous predators roaming the area.
Its and our vision
Scientific research suggests that this species has trichromatic vision, like us humans. Meaning it can process three independent channels for conveying colour information, derived from the 3 different types of cone cells in the eye. No wonder they opted for such a beautiful colour pattern!
With our vision, we also mean the broader context. At the moment, we are restructuring and rebuilding our website to present our work and services as well as our vision in a new light (About us).
There is so much more to learn and discover
Art by nature: What a beautiful world we live in! This video was filmed during a night dive at Wakatobi Dive Resort (Indonesia). There are many more clips from our wonderful time as Dive Experience Managers in Wakatobi: Sulawesi Splendour.