Bumphead Parrotfish

This is also a picture I took during diving at Sipadan Island on the 13th December 2012. A group of Bumphead Parrotfish. 

Here, I write down a facts about this fish.

Family name: Scaridae
Order name: Perciformes 
Common name: Bumphead, Giant humphead, Green humphead, Double-headed parrotfish and other variations on these names 
Scientific name: Bolbometopon Muricatum

The humphead is the largest of the parrotfishes at 130 cm in length and weighing up to 46 kg. They are distinguished by beak-like teeth plates only partially covered by fleshy lips. Males and females look the same in this species. The juveniles start out a greenish brown colour with 5 bands of whitish spots arrayed vertically along their body. As the adults mature they develop a pronounced bump on their vertical head profile. When fully grown they range from olive or bluish-green to slate grey, with a yellowish to pink blaze down the front of their face.

Adult bumpheads are sometimes confused with the juvenile Napoleon wrasse, which can be differentiated by 2 black lines running behind its eye.

Behaviour: Gregarious by nature, bumphead parrotfish form shoals of 20 to 100 fish, resting in shallow, sandy lagoon flats, around caves and shipwrecks at night. During the day, the adults move to the seaward side as they scour the coral reef for food.

In areas where they are exposed to fishing pressure or high sea traffic, humpheads have become wary of reefs near human habitats. In marine protected areas these gentle giants are far more approachable and even indifferent to divers. You can often see them tearing around before your eyes and seemingly not paying you the slightest bit of notice.

Feeding Habit: Bumphead parrotfish are primarily corallivores. Feeding on benthic algae and live coral during the day, the school leaves the reef lagoon with the adults moving further afield, while the juveniles remain closer to home in seagrass beds. Humpheads truly live up to their name by occasionally bumping the coral with their heads, breaking it into smaller pieces that are more easily consumed.

They are equipped with pharyngeal teeth at the back of their throat to sufficiently grind the hard coral into a digestible paste. Any indigestible elements are passed out in the fish's faeces, creating vital sediment. As each fish consumes up to 5 tons of reef carbonates per year, they are important coral sand producers, positively affecting the resilience of the coral reef's ecosystem. Of course this fine white sand often ends up washing ashore, so think of that the next time you are on a soft powdery beach. You may be grateful that the earth beneath your feet had passed through some bumpheads' alimentary canal, although fish poop might not be a great conversation topic during a romantic stroll!

Life Cycle: The newly-hatched humphead larvae drift with the current, where they feed on algae until they can seek refuge in the shallows, preferring mangrove forest root systems and seagrass lagoons where they feed primarily on seaweed for up to 3 years before joining the adults in the reefs.

Slow to mature, bumphead parrotfish only begin reproduction late in their cycle, when no smaller than 60 cm in length. Considering they live up to 40 years and grow to 130 cm, this results in slow replenishment of the species.