Triggerfish

Picasso triggerfish ( Rhinecanthus aculeatus )

The triggerfish ( Balistidae ) are a family of the order of the pufferfish relatives ( Tetraodontiformes ). They inhabit tropical and subtropical areas of the Atlantic, Indian and Pacific Oceans, especially coral reefs. Only a few species live in pelagic open ocean. The gray triggerfish ( Balistes capriscus ) also occurs in the Mediterranean and is the only triggerfish Irrgast in the North Sea.

Features

Triggerfish are 16 centimeters to one meter long and have a powerful, high -built and laterally flattened body. They are often brightly colored and strikingly patterned. Your body is covered with a thick skin and small, non- overlapping scales. The scales often bear small spines. Triggerfish have only 18 vertebrae. The spatula, crescent - or lyriform caudal fin has twelve fin rays. The head with the high-lying and far back eyes that can move independently of each other, occupies a very large part - a body length - up to a third. The size of the Suspensoriums Hyomandibel and quadrate are unusual widely moved apart, but nevertheless firmly connected by the very large Präoperculum. Purpose of this striking design is to protect the eyes in the food supply. The mouth itself is very small, but equipped with strong, chisel- like teeth. In the upper jaw usually sit on each premaxilla four teeth in the first and three teeth in the second row, for a total of 14 teeth. Triggerfish swim mainly by undulating ( " flappende " ) movements of their symmetrically opposing soft-rayed second dorsal fin and the anal fin. What is striking is their often oblique swimming position. The tail acts as a rudder and is only used at higher speeds for propulsion ( balistiformes swimming).

The trigger mechanism

The hartstrahlige, first dorsal fin has three fin rays, the third can be very small or absent. The first and longest fin ray forms with the second fin ray the trigger mechanism, which the fish owe their German names. The first fin spine can be positioned and fixed by the second by this snaps in a V-shaped groove on the back of the first. Thus, for the first fin ray lay down again until the second is apportioned by muscle pull backwards. Is also the third dorsal spine is present, it must be allocated before the second. Together with the fused pelvic fins - which represent only a sawed, strong and consisting of coalesced radiation fin spine, which is connected to the pelvis by a hinge and a flexible skin - can the fish stall in columns of coral and rocky reefs and are difficult to capture by predators. In this position, the animals sleep well. They usually use the same place to sleep and change it only with increasing body size. When swimming, the hard jets are put back into a groove on the back and are then not visible. The same pusher mechanism also possess the closely related file fish.

Marriage was known to the handle mechanism, called the Balistiden because of the large, thick back spike horn fish - especially since the " horn " so close to the head lies ( " Horn " and " brain " are of the same origin - both belong to the head).

Lute

Triggerfish are among the fish that are able to produce clear vocal sounds. You can grind their teeth, rub parts of the shoulder girdle to the swim bladder and thus produce drumming sounds. Flip up their first dorsal fin ray up and down and let the second one and snap out, so you can hear a loud cracking.

Lifestyle and diet

Triggerfish live mainly near the ground and solitaire, Rhinecanthus species form flocks in their youth, the Redfang triggerfish and the Indian Triggerfish daytime form loose groups. The solitary species are revier forming. Your individual density in suitable habitats is often very high.

Trigger fish feed mainly on hard-shelled invertebrates such as crustaceans, mollusks, echinoderms but also corals, sponges, sea squirts, small fish, zooplankton, algae and seaweed are eaten by some species. In their search for prey they can lift their mouths with stones or coral or create a jet of water, which exposes their food on the ocean floor (hence so narrow gill slits ). Sea urchins are turned over by some trigger fish species with a jet of water, so that they lie with their vulnerable side up.

Reproductive and territorial behavior

Triggerfish show little gender differences, mostly the males are larger and a little more intense. Often the females have small territories within a larger one male belonging coalfield. Lay their eggs, most bottom-dwelling species into large funnel-shaped pits that they dig by blowing a jet of water in the sandy soil. Is spawned at dusk, often a day before new moon. The nest consists of tiny, stitched in a disk-shaped masses on the underground eggs and befächelt from the female, guarded and defended very aggressive. An enemy they warn of an attack by a headstand. Then they swim with great speed toward the opponent and turn off at the last moment. If the enemy still closer, ram or bite him in the next attack. Nest guarding giant triggerfish attack scuba divers, as they approach to less than ten meters. In the area of defense they drum.

The larvae hatch after 12 to 24 hours, then live very long in the open ocean pelagic and spread so far. In some species the young fish are already 15 inches long when they go to the ground level of life of the adult animals.

The pelagic species spawn in the open ocean and operate no brood care. Their eggs are pelagic.

Outer systematics

Triggerfish are one of the pufferfish relatives ( Tetraodontiformes ) and, together with its sister group, the filefish ( Balistidae ) the superfamily Balistoidea. In previous publications the file fish are often still counted as a subfamily Monacanthinae to trigger fish.

Species

There are twelve genera and 43 species:

• Abalistes ( Bloch & Schneider, 1801) Stars triggerfish ( Abalistes stellaris )

• Orange striped triggerfish ( Balistapus undulatus ) ( Park, 1797)

• Gray Triggerfish ( Balistes capriscus ) Gmelin, 1789
• Balistes ellioti
• Spinner triggerfish ( Balistes polylepis )
• Balistes punctatus
• Balistes rotundatus
• Queen triggerfish ( Balistes Vetula) Linnaeus, 1758
• Balistes willughbeii

• Leopard triggerfish ( Balistoides conspicillum ) ( Bloch & Schneider 1801)
• Giant Triggerfish ( Balistoides viridescens ) ( Bloch & Schneider 1801)

• Snowflakes triggerfish ( Canthidermis maculatus )
• Canthidermis macrolepis
• Canthidermis sufflamen

• Indian triggerfish ( Melichthys indicus)
• Black Triggerfish ( Melichthys niger) ( Bloch, 1786)
• Widows triggerfish ( Melichthys vidua )

• Redfang triggerfish ( Odonus niger) ( Rüppell, 1836)

• Gelbsaum triggerfish ( Pseudobalistes flavimarginatus ) ( Rüppell, 1829)
• Blue stripe Triggerfish ( Pseudobalistes fuscus ) ( Bloch & Schneider, 1801)
• Pseudobalistes naufragium

• Rhinecanthus abyssus
• Picasso triggerfish ( Rhinecanthus aculeatus ) (Linnaeus, 1758)
• Red sea Picasso triggerfish ( Rhinecanthus assasi ) ( Forsskål, 1775)
• Rhinecanthus cinereus
• Rhinecanthus lunula
• Diamond Picasso triggerfish ( Rhinecanthus rectangulus ) ( Bloch & Schneider, 1801)
• Belly spot - Picasso triggerfish ( Rhinecanthus verrucosus ) (Linnaeus, 1758)

• Sufflamen albicaudatum
• Boomerang triggerfish ( Sufflamen bursa ) ( Bloch & Schneider, 1801)
• White border triggerfish ( Sufflamen chrysopterum ) ( Bloch & Schneider, 1801)
• Sufflamen fraenatum
• Sufflamen verres

• Blue Throat Triggerfish ( Xanthichthys auromarginatus ) ( Bennett, 1832)
• Xanthichthys caeruleolineatus
• Xanthichthys greenei Pyle & Earle, 2013
• Xanthichthys lineopunctatus
• Xanthichthys mento
• Sargasso triggerfish ( Xanthichthys ringens ) (Linnaeus, 1758)

• Xenobalistes punctatus
• Xenobalistes tumidipectoris

Fossil record

With Oligobalistes robustus from the lower Oligocene of the North Caucasus also a fossil triggerfish is known.

Use

In contrast to many other pufferfish relatives triggerfish are not toxic, not even their innards, and be consumed by humans. However, the algae- eating species can trigger a ciguatera poisoning in humans. Especially colorful triggerfish species are captured alive also to aquarium purposes and exported to wealthy countries. However, they are usually too large for private aquariums and are snappy towards socialized fish. Even in large public aquariums, they are like shown.