Blue Season Bali Newsletter May 2010
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Ever wonder where that fine white sand that you love to feel between your toes comes from?
Normally travelling in schools and sounding like a marching army the bumphead parrotfish noisily crunch their way through acres of coral reef and excrete wafts of fine sand onto the ocean floor. Probably not a great topic for conversation during a romantic stroll!
To find yourself surrounded by a school of these large magnificent fish as they munch on the reef around you, is indeed an experience to remember as they will never win a beauty contest, but they do make great subjects for all photographers.
Courtship occurs during the early morning of a lunar cycle and starts with large gatherings of up to 100, tightly packed bump-heads. 2 fish will voluntarily rise, front-to-front, to approximately 1m below the surface, where they discharge a haze of sperm and eggs. The couple then returns to the shoal.
The newly-hatched bump-head larvae drift with the current, where they feed on algae until they can seek refuge in the shallows, preferring mangrove forest root systems and sea-grass lagoons where they feed primarily on seaweed for up to 3 years before joining the adults in the reefs. Both males and females look the same and the juveniles start out with 5 whitish vertical stripes on a background of greenish brown. As they mature they develop a pronounced bump on their vertical head profile and when fully grown they range in colour from olive or bluish-green to slate grey, with a yellowish to pink blaze down the front of their face.
Parrotfish are hermaphrodites, that is, both sex organs being found in every fish. They commonly begin life as females, and undergo physical and physiological changes to become males. Sex change typically happens when the resident male leaves, or dies, with the top female changing sex to replace him.
They are the largest of the parrotfish family at 130 cm in length and weighing up to 46 kg; each adult fish can ingests over 5 tons of structural reef carbonates per year they may ram their head against corals breaking it into smaller pieces that are more easily consumed and also contributing significantly to the bio-erosion of reefs.
They don’t get to be this size over night, they are slow growing and can live for up to 40 years, they sleep in caves and shipwrecks at night. If you take the night dive at Tulamben on the USAT Liberty shipwreck you will have a great chance to see this for yourself. However this does make them one of the most vulnerable species to fishing and spear fishing.
Juvenile Napoleon wrasse are sometimes confused with the bump-head, but can be differentiated by 2 black lines running behind its eye, and the Bump-head has beak-like teeth plates that are only partially covered by fleshy lips. Behind these plates 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, yes, that white sand between your toes.
Bump-heads form shoals of 20 to 100 fish, resting in shallow, sandy lagoon flats, around caves and shipwrecks at night (USAT Liberty shipwreck). During the day, the adults move to the seaward and can often be seen at the Drop Off in Tulamben as they scour the coral reef for food. These gentle giants are approachable and even indifferent to divers as it seems that divers do not seem to bother them in the slightest bit.
Contact us if you would like to see the fantastic diving in Bali.
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