Titan triggerfish is a large species of triggerfish that belongs to the family of balistidae. Triggerfish are seen in the Indo-West and Central Pacific region, southwestern to north-western Western Australia, the central coast of New South Wales, and the Great Barrier Reef. This fish is easily found singly or in pairs protecting their areas over slopes of deep lagoons and seaward reefs. Juveniles are mainly found close to isolated patches of branching corals over protected shallow, sandy areas of reefs. The titan triggerfish is diurnal and solitary.
They are called mustache triggerfish as they have black markings above the mouth that look like a mustache. Its body is heavily scaled and is generally green to dark grey in color, with yellow or green fins with black tips, and a lower jaw, dark grey or purple in color. In Thailand, the fish are predominantly yellow in color.
Although it will sometimes eat smaller fish, the titan triggerfish is not solely a piscivore. Instead, its primary diet consists of several species of echinoderms, crustaceans, mollusks, tube worms, and living coral. They have powerful sharp teeth. The titan triggerfish uses its powerful bite to break pieces off and crush them to extract the meat. These are the workers of the reef, often busy turning over rocks, stirring up the sand, and biting off pieces of branching coral. This activity often stirs up nearby coral parts and small organisms, allowing other fish to feast on the leftovers.
While individuals have been observed in the wild eating juvenile crown-of-thorns starfish, sea urchins seem to be the favored target, including the various long-spined, somewhat venomous Diadema species. The titan gets past their defenses by seizing the tips of the spines in its mouth and flipping the urchin upside down. This exposes the relatively unprotected underside of the urchin so the titan triggerfish can dig the meat out of the spiny shell.
The diet of the titan triggerfish makes its impact on the reef rather neutral, for while it feeds on the corals and tube worms of the reef itself, it also feeds on other reef predators and helps to keep their populations in check.
They have independently rotating eyes, and their pelvic fins are fused into a single spine.
They have 2 dorsal fins, the first of which is comprised of 3 spines, and this is where the triggerfish derives its name. The spine is also held erect as a warning to other fish to stay away. If this warning is ignored, they are known to charge at anything and anyone. At night or when threatened, the fish will wedge itself into a coral crevasse and erect its dorsal fin wedging itself in tight. The first spine is locked in place by the second spine and once that's in place, the fish is virtually immovable, resulting in the titan triggerfish not being considered an easy meal. Although not much is known about what in particular preys on titans, one thing is for sure, they can defend themselves quite well.
The triggerfish search for mating partners and are known to do mating dances with the chosen one. Both sexes will vigorously protect the nesting area. While nesting or not, the male is usually aggressive and can attack unprovoked; a female guarding her nest can be equally aggressive. They will deftly defend the nest even against intruders much bigger than themselves. The territory around the nest is roughly cone-shaped and divers who accidentally enter it may be attacked. The threat posture includes the triggerfish facing the intruder while holding its first dorsal spine erect. It may also roll onto its side, allowing it a better look at the intruder. Their bites can cause serious infection as they contain a natural poison called Ciguatoxin. The titan triggerfish will not always bite but can swim at snorkelers and divers escorting them out of their territory.
Sexually distinctive, the titan triggerfish will lay eggs that are fertilized externally. Eggs are laid after some preparation of the nest. They create a depression in the sand of the chosen nesting area by fanning it with their caudal and dorsal fins. Titan triggerfish spawn for about 4 days a month. The male will guard the nest and blow water over the eggs, ensuring a good supply of fresh water and oxygen. Once the larvae hatch, they will swim away, presumably into the protection afforded by the coral reef. Early on in the life cycle, zooplankton will be the source of nourishment until such time as the juvenile has matured enough to take on other delicacies of the coral reef.
#Nature #CoralReef #CrownofthornsStarfish
5 ноя 2021
