Triggerfish

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Triggerfish
Titan triggerfish (Balistoides viridescens)
Titan triggerfish (Balistoides viridescens)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Tetraodontiformes
Family: Balistidae
Genera

See text.

Triggerfishes are brightly colored fish of the family Balistidae. Often marked by lines and spots, they inhabit warm coastal waters of the Atlantic, Mediterranean and the Indo-Pacific.

Contents

[edit] Anatomy and appearance

Their size varies from 30 to 75 cm (1 to 2½ ft).

Triggerfish have a roundish, laterally flat body with an anterior dorsal fin. They can erect the first two dorsal spines: the first one locks and the second one unlocks. This prevents predators from swallowing them or pulling them out of their holes. This locking and unlocking behaviour is why they are named 'triggerfish'.

They have a small pectoral fin, fused to one spine. Unlike the spine of a filefish, the spine of the triggerfish can be held in place by a second spine to make the fish more threatening to the predator. Their small eyes, situated on top of their large head, can be rotated independently. They have tough skin, covered with rough rhomboid-shaped scales that form a tough armour on their body. A big, angular-shaped head extends into a snout with strong jaws and sharp teeth, made for crushing shells. Each jaw contains a row of eight teeth, while the upper jaw contains another set of six plate-like teeth.

[edit] Behavior

Picasso triggerfish bite
Picasso triggerfish bite

Most are solitary and diurnal. They feed on hard-shelled invertebrates, a few feed on large zooplankton or algae. They lay their demersal eggs in a small hole, dug in the ground. Some species guard their eggs.

A few of the triggerfish species can be quite aggressive during reproduction season. In particular Picasso triggerfish and titan triggerfish viciously defend their circular nests against any intruders, including scuba divers and snorkelers. Their territory extends in a cone shape from the nest to the surface, so swimming upwards puts one further into the fishes' territory. A horizontal swim away from the nest site is the most sensible course of action when confronted by an angry triggerfish. In contrast to the relatively small Picasso triggerfish, the titan triggerfish poses a serious threat to inattentative divers due to its large size and powerful teeth.

Some species of triggerfish are known to make a sound akin to a grunt or snarl when taken out of the water.

[edit] Gallery

Queen triggerfish, Long Cay, Belize

Clown triggerfish, New Hanover Is., Papua New Guinea

Boomerang triggerfish, Kona, Hawaii

Lagoon triggerfish (Rhinecanthus aculeatus)

Redtoothed triggerfish (Odonus niger) feeding on plankton

Titan triggerfish (Balistoides viridescens) with orange-lined triggerfish (Balistapus undulatus) and moorish idols at the reef of Fihalhohi, Maldives

Orange-lined triggerfish (Balistapus undulatus)

Black triggerfish (Melichthys niger) and its reflection in the water surface

Halfmoon triggerfish

Pink tail triggerfish

Rhinecanthus rectangulus feeding on invertebrates in the sand

[edit] Genera

[edit] References

  • "Balistidae". FishBase. Ed. Rainer Froese and Daniel Pauly. December 2005 version. N.p.: FishBase, 2005.
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