Today it’s time for something a little different. So far in this series we have been looking at some of the species that we see on our dives but don’t really know much about. Now we have made it around the world’s oceans once, it’s about time we revisit some areas and look at some of the showstopper animals that can be found in these areas. You might already know something about some of these but hopefully I can tell you something new about them!Humphead wrasse
This edition’s fish is one of the most impressive and visually striking fish on the reef, the Humphead Wrasse, or as we used to call them in Australia, Wallies!
The Humphead Wrasse, also known as the Napoleon wrasse, the Napoleonfish or Maori wrasse, is the largest member of the Labridae family. The Wrasse family holds over 600 species and can be identified by the fact they then to swim with their pectoral fins rather than their tail fins.
The Humphead Wrasse
What’s in a name?
The Humphead wrasse gets its name from the hump like protrusion on its forehead this is also where is gets the name Napoleon from. The hump of its head kind of looks like the tricorn hat worn by Napoleon Bonaparte and other naval captains of that time. The name Maori wrasse however comes from the vivid blue lines on its face, resembling the tribal face tattoos of the Maori people. The scientific name come from two main words, ‘cheilos’ meaning lip and ‘undulatus’ meaning wavy or undulating. It is clear to see why both of these names were chosen, the fish is covered in wavy lines and has huge lips!
Habitat and distribution.
While these fish can be found from the Red Sea to the western Pacific, they are most common in the Red Sea and Australian waters. They are found in Asia but are much rarer due to over fishing in this region. As an adult and a juvenile they can be found in different parts of the reef. Juveniles are often found inshore and close to shallow reef areas, amongst the branching corals and in shallow lagoons with sandy bottoms. Adults however are found more offshore and in deeper waters, tending to prefer coral pinnacles and steep coral walls and slopes. They can be found up to 100m, with fully grown adults occasionally found down as far as 160m.
Looks that kill.
This fish goes through quite a change over its lifespan. When they are born their bodies are a creamy white with brown and black spots all down it. There are faint lines of black going through the eyes of the fish which maintain in some form throughout its life.
As they change from a fry into a juvenile the spots change into dark coloured scales on the same pale background. The tail fin also shows a bright yellow edge during this stage. On its face the dark lines are also now more visible but the lips are still small and thin.
Finally, as the fish grows into an adult its body becomes a dark greeny brown with its scales becoming dark and defined, it’s the yellow tail streak also becoming a pale white. This is where the lips start to become very large and the lump on its head starts to grow, giving the fish its distinctive look. The lines through its eyes are still visible, giving the fish a look like its smeared its eyeliner. During this phase is also when the intricate lines and patterns form on the face of the fish, appearing a bright orange or pink against the green background when photographed.
Usually this is how the fish will remain, a beautiful dark green, but some individuals can change again to show a deep electric blue face and a lime green body. These fish are the oldest and largest of Humphead wrasse and are referred to as supermales.
Humphead wrasse are protogynous hermaphrodites, like a few of the other fish we have talked about in this series. This means that they are all born one sex, in this case female, before changing sex in response to outside stimuli. What happens here is that there will be a few that change into males but if there are already male fish in the environment they will stay as females. It is not known as to why this change happens or why it goes female to male but one theory stands that as younger fish they want to be able to release eggs as quickly as possible, bolstering the population. The change to males happens when the fish is around 7 to 9 years old, however egg production costs a lot of energy so why they would produce eggs young rather than when they are mature is still a mystery.
After this sex change the lifespan of the male is reduced, possibly as a result of the energy cost to change. While Humphead wrasse are able to transition straight to males from fry, this is very rarely seen in the wild and those that are born male never become dominant alpha males.
The supermales are distinguished from the females by having the large lump on their heads and the blue/green colouration, the females remain smaller with a lighter, more juvenile colouration. They are broadcast spawners, releasing eggs and sperm into the water column, with breeding taking place in large groups of over 100 individuals. Spawning has been seen in most months of the year, albeit with some slight seasonal variation and it is believed to be linked to the lunar cycles.
Life on the reef.
You will find the Humphead wrasse in different places depending on how old it is. When they are small they like to hide in the branches of hard coral and amongst the cracks and crevices in the reef. This provides them with plenty of shelter as well as a place to find food. As they increase in size and outgrow their habitat they move to the edge of the reef and further down the slopes.
They are one of the biggest fish that you will see on the reef, with males reaching up to 2m and weighing over 180kg. Females generally are a little smaller, staying around 1m in length. It is also one of the oldest fish you can find, with females living over 50 years and males slightly less around 45 years. As they take around 5 to 7 years to reach maturity and 9 years to become males, these fish are very susceptible to overfishing.
These fish have very powerful jaws which allow them to eat all sort of different types of prey. They eat fish, molluscs, crustaceans and echinoderms like urchins. They are also immune to most toxins meaning they can eat the invasive Crown-of-Thorns starfish, music to the ears of biologists and dive guides!
I have been very lucky to see these fish in the Red Sea, the Philippines and Australia and each time I see them they make me smile. The smaller individuals tend to keep away from divers, either moving closer to the reef or deeper into the blue. Adult males however are quite a friendly fish, interacting with divers and checking them out. They allow divers to get very close to take photos and are happy to follow divers around on a dive. Sometimes you will see people touching or stroking them as they can seem tame, but this is a bad idea! Chemicals and oils on your hands can burn the bodies of the fish, so don’t touch!
When photographing them, try to go easy on the strobes as while they are friendly they do not have eyelids. Constant flashing in their eyes is bad for them, as I’m sure you can understand.
The bottom line.
The last time I saw these fish was in the Red Sea and you will have a great chance to see one on the St. Johns itinerary which we currently have on a special offer for the 21st of June. This trip will be on the Hurricane but we have plenty of other Red Sea trips you can see these fish on, such as the Wrecks and Reefs or the Simply the best. It is a real treat to see one of these giant fish cruise in out of the blue on the wall, I hope they come over and say hi!