Triggerfish Temporal range: | |
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Lagoon triggerfish | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Tetraodontiformes |
Family: | Balistidae A. Risso, 1810 |
Genera [1] | |
Abalistes Contents |
Triggerfish are about 40 species of often brightly colored fish of the family Balistidae. Often marked by lines and spots, they inhabit tropical and subtropical oceans throughout the world, with the greatest species richness in the Indo-Pacific. Most are found in relatively shallow, coastal habitats, especially at coral reefs, but a few, such as the oceanic triggerfish (Canthidermis maculata), are pelagic. While several species from this family are popular in the marine aquarium trade, they are often notoriously ill-tempered. [2] [3]
The largest member of the family, the stone triggerfish (Pseudobalistes naufragium) reaches 1 m (3.3 ft), [4] but most species have a maximum length between 20 and 50 cm (8–20 in). [2]
Triggerfish have an oval-shaped, highly compressed body. The head is large, terminating in a small but strong-jawed mouth with teeth adapted for crushing shells. The eyes are small, set far back from the mouth, at the top of the head. The anterior dorsal fin is reduced to a set of three spines. The first spine is stout and by far the longest. All three are normally retracted into a groove. Characteristic of the order Tetraodontiformes, the anal and posterior dorsal fins are capable of undulating from side to side to provide slow movement and comprise their primary mode of propulsion. The sickle-shaped caudal fin is used only to escape predators.
The two pelvic fins are overlaid by skin for most of their length and fused to form a single spine, terminated by very short rays, their only external evidence. Gill plates (opercula), although present, are also not visible, overlaid by the tough skin, covered with rough, rhomboid scales that form a stout armor on their bodies. The only gill opening is a vertical slit, directly above the pectoral fins. This peculiar covering of the gill plates is shared with other members of the Tetradontae. Each jaw contains a row of four teeth on either side, while the upper jaw contains an additional set of six plate-like pharyngeal teeth.
As a protection against predators, triggerfish can erect the first two dorsal spines: The first (anterior) spine is locked in place by erection of the short second spine, and can be unlocked only by depressing the second, "trigger" spine, hence the family name "triggerfish".
With the exception of a few species from the genus Xanthichthys , the sexes of all species in this family are similar in appearance.
The anatomy of the triggerfish reflects its typical diet of slow-moving, bottom dwelling crustaceans, mollusks, sea urchins and other echinoderms, generally creatures with protective shells and spines. Many will also take small fishes and some, notably the members of the genus Melichthys , feed on algae. [2] A few, for example the redtoothed triggerfish (Odonus niger), mainly feed on plankton. [2] They are known to exhibit a high level of intelligence for a fish, and have the ability to learn from previous experiences. [3] [5]
Some triggerfish species can be quite aggressive when guarding their eggs. Both the Picasso (Rhinecanthus aculeatus) and titan triggerfish (Balistoides viridescens) viciously defend their nests against intruders, including scuba divers and snorkelers. Their territory extends in a cone from the nest toward the surface, so swimming upwards can put a diver further into the fishes' territory; a horizontal swim away from the nest site is best when confronted by an angry triggerfish. Unlike the relatively small Picasso triggerfish, the titan triggerfish poses a serious threat to inattentive divers due to its large size and powerful teeth. [6]
Triggerfish males migrate to their traditional spawning sites prior to mating and establish territories. Some male species (i.e. Balistes carolinensis and Pseudobalistes flavimarginatus ) build hollow nests within their territories. [7] Triggerfish males are fierce in guarding their territories as having a territory is essential for reproduction. A male's territory is used for spawning and parental care. Most male territories are located over a sandy sea bottom or on a rocky reef. A single territory usually includes more than one female, and the male mates with all of the females residing in or visiting his territory (polygyny). In Hachijojima, Izu Islands, Japan, one male crosshatch triggerfish ( Xanthichthys mento ) has up to three females in his territory at the same time, and mates with them in pairs. Each male red-toothed triggerfish ( Odonus niger ) mates with more than 10 females in his territory on the same day. [8] Yellow margin triggerfish ( Pseudobalistes flavimarginatus ) also exhibit polygyny.
Triggerfish spawning is timed in relation to lunar cycles, tides, and time of changeover of tides. In relation to lunar cycles, eggs are observed 2–6 days before the full moon and 3–5 days before the new moon. In relation to tides, spawning happens 1–5 days before the spring tide. In relation to timing of tides, eggs are observed on days when high tides take place around sunset. [9]
Male and female triggerfish perform certain prespawning behaviors: blowing and touching. [8] A male and female blow water on the sandy bottom (usually in the same spot at the same time) and set up their egg site. They touch their abdomens on the bottom as if they are spawning. During actual spawning, eggs are laid on the sandy sea bottom (triggerfish are demersal spawners despite their large size). Eggs are scattered and attached to sand particles. Triggerfish eggs are usually very small (diameter of 0.5–0.6 mm) [9] [10] and are easily spread by waves. After spawning, both the male and female participate in caring for the fertilized eggs (biparental egg care). A female triggerfish stays near the spawning ground, around 5 m off the bottom, and guards the eggs within her territory against intruders. Some common intruders include Parupeneus multifasciatus, Zanclus cornutus, Prionurus scalprum , and conspecifics. Besides guarding, females roll, fan, and blow water on eggs to provide oxygen to the embryos, thereby inducing hatching. [11] This behavior of female triggerfish is called "tending", and males rarely perform this behavior. A male triggerfish stays farther above the eggs and guards all the females and eggs in his territory. Males exhibit aggressive behaviors against conspecific males near the boundaries of their territories.
In crosshatch triggerfish ( Xanthichthys mento ) and yellow margin triggerfish ( Pseudobalistes flavimarginatus ), eggs are spawned in the morning and they hatch after the sunset on the same day. After hatching of embryos, the female crosshatch triggerfish leaves the male's territory. This mating system is an example of male-territory-visiting polygamy. Triggerfishes exhibit other types of mating systems, as well, such as a nonterritorial-female (NTF) polygyny and territorial-female (TF) polygyny. In NTF polygyny, nonterritorial females stay in the male's territory and reproduce. In TF polygyny, a female owns territory within a male's territory and will spawn in her territory. [8]
Triggerfish lay their demersal eggs in a small hole dug in the sea bottom. Off Florida, juveniles of some species of triggerfishes are found in floating Sargassum , where they feed on the small shrimp, crabs, and mollusks found there. [12]
Some species of triggerfish, such as the titan triggerfish, may be ciguatoxic and should be avoided. [2] Others, however, such as the grey triggerfish (Balistes capriscus), are edible. [13]
Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising more than 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than 10 cm (3.9 in) in length, and the family includes some of the smallest vertebrates in the world, such as Trimmatom nanus and Pandaka pygmaea, Trimmatom nanus are under 1 cm long when fully grown, then Pandaka pygmaea standard length are 9 mm (0.35 in), maximum known standard length are 11 mm (0.43 in). Some large gobies can reach over 30 cm (0.98 ft) in length, but that is exceptional. Generally, they are benthic or bottom-dwellers. Although few are important as food fish for humans, they are of great significance as prey species for other commercially important fish such as cod, haddock, sea bass and flatfish. Several gobiids are also of interest as aquarium fish, such as the dartfish of the genus Ptereleotris. Phylogenetic relationships of gobiids have been studied using molecular data.
The clown triggerfish, also known as the bigspotted triggerfish, is a demersal marine fish belonging to the family Balistidae, or commonly called triggerfish.
The Redtoothed triggerfish is a triggerfish of the tropical Indo-Pacific area, and the sole member of its genus. Some other common names include blue triggerfish, redfang triggerfish, redtoothed filefish, and Niger triggerfish.
The yellowmargin triggerfish, pineapple trigger, yellowface triggerfish or yellow-face triggerfish is a marine fish in the family Balistidae. It is found in coastal tropical waters and reefs of the Indo-Pacific from the Red Sea south to Natal, South Africa and east from southern Japan south to Indonesia, Philippines and Samoa, at water depths from 2–50 m (6.6–164.0 ft).
Pseudobalistes fuscus is a fish belonging to the family Balistidae.
The lagoon triggerfish, also known as the blackbar triggerfish, the Picasso triggerfish, or the Picassofish, is a triggerfish, up to 30 cm in length, found on reefs in the Indo-Pacific region.
The filefish (Monacanthidae) are a diverse family of tropical to subtropical tetraodontiform marine fish, which are also known as foolfish, leatherjackets or shingles. They live in the Atlantic, Pacific and Indian Oceans. Filefish are closely related to triggerfish, pufferfish and trunkfish.
The titan triggerfish, giant triggerfish or moustache triggerfish is a large species of triggerfish found in lagoons and at reefs to depths of 50 m (160 ft) in most of the Indo-Pacific, though it is absent from Hawaii. With a length of up to 75 centimetres (30 in), it is the largest species of triggerfish in its range.
The ocellaris clownfish, also known as the false percula clownfish or common clownfish, is a marine fish belonging to the family Pomacentridae, which includes clownfishes and damselfishes. Amphiprion ocellaris are found in different colors, depending on where they are located. For example, black Amphiprion ocellaris with white bands can be found near northern Australia, Southeast Asia, and Japan. Orange or red-brown Amphiprion ocellaris also exist with three similar white bands on the body and head. Amphiprion ocellaris can be distinguished from other Amphiprion species based on the number of pectoral rays and dorsal spines. Amphiprion ocellaris are known to grow about 110 mm long. Like many other fish species, females are, however, larger than males. The life cycle of Amphiprion ocellaris varies in whether they reside at the surface or bottom of the ocean. When they initially hatch, they reside near the surface. However, when Amphiprion ocellaris enter into the juvenile stage of life, they travel down to the bottom to find shelter in a host anemone. Once they find their anemone, they form a symbiotic relationship with them.
The orange-lined triggerfish is a demersal triggerfish. Although Balistapus is a monotypic genus, it is closely related to the genus Balistoides.
The Banggai cardinalfish is a small tropical cardinalfish in the family Apogonidae. It is the only member of its genus. This attractive fish is popular in the aquarium trade. It is among the relatively few marine fish to have been bred regularly in captivity, but significant numbers are still captured in the wild and it is now an endangered species. The detrimental impact of humans on its environment and certain fatal diseases threaten this species' numbers significantly. Iridovirus diseases are known to be significant reason for fish mortality.
The grey triggerfish, or gray triggerfish, is a species of ray-finned fish in the triggerfish family. The species is native to shallow parts of the western Atlantic from Nova Scotia to Argentina and also the eastern Atlantic, the Mediterranean Sea and off Angola on the west coast of Africa.
Although most species in the Red Sea pose no threat to humans, there are a few notable exceptions.
The leopard coral grouper, also known as the common coral trout, leopard coral trout, blue-dotted coral grouper or spotted coral grouper, is a species of marine ray-finned fish, a grouper from the subfamily Epinephelinae which is part of the family Serranidae, which also includes the anthias and sea basses. It is found in the Western Pacific Ocean.
Ophioblennius atlanticus, also known as the redlip blenny and the horseface blenny, is a species of combtooth blenny, family Blenniidae, found primarily in the western central Atlantic ocean. Redlip blennies can be found in coral crests and shallow fringing reefs. They are highly territorial and attack intruders with two long, sharp canine teeth. The adults are found at depths of 10 to 20 meters, and the eggs are benthic. The adults may reach up to four inches in length when fully grown, and they have large reddish lips, from which they attained their names. Redlip blennies largely feed on algae.
Xanthichthys mento, the redtail triggerfish, blue-throat triggerfish, or crosshatch triggerfish, is a species of triggerfish from the Pacific. It inhabits outer-reef areas at depths of 6–131 m (20–430 ft), and feeds on zooplankton. Xanthichthys mento grows to a size of 29 cm (11 in) in length and occasionally makes its way into the aquarium trade.
Sufflamen bursa, sometimes known as Lei Triggerfish, bursa triggerfish, scythe triggerfish or boomerang triggerfish, is a triggerfish from the Indo-Pacific. Its name is derived from the two markings behind its eyes that wrap around the fish similar to a Hawaiian Lei. The color of these markings changes depending on the fish's mood, in which case the colors may alter from yellow, dark brown, and black. It is a species of reef fish found in reef ecosystems in the Indo-Pacific, including Japan, Australia, and Hawaii. It occasionally makes its way into the aquarium trade.
Rhinecanthus lunula, commonly known as the halfmoon picassofish, is a species of balistid triggerfish first described by John E. Randall and Roger C. Steene in 1983. It belongs to the Indo-Pacific triggerfish genus Rhinecanthus.
Cirrhilabrus finifenmaa, also known by its common name rose-veiled fairy wrasse, is a rainbow-colored wrasse that is native to the reefs of the Maldives.