The term “trumpet fish” refers to 3 species of extremely elongated and very similar fish, all belonging to the family Aulostomidae, in turn included in the order Syngnathiformes. Although they do not look very similar, trumpet fishes share a higher taxon with seahorses.
The very name of the genus Aulostomus gives us information about the characteristics of these fish, since aulas means flute in Greek and tomus (stoma) refers to its mouth. If you want to know more about this atypical group of acanthopterygians, read on.
Habitat of the trumpet fish
First of all, we must emphasize that the genus Aulostomus comprises 3 different species: Aulostomus chinensis, Aulostomus maculatus and Aulostomus strigosus. We are going to focus on the most common trumpetfish of all (Aulostomus maculatus), although we will also give some general information about the rest of the relatives.
As a genus, trumpetfishes are found in various tropical waters around the globe, although 2 species are distributed in the Atlantic (Aulostomus maculatus and Aulostomus strigosus) and the other inhabits the Indo-Pacific (Aulostomus chinensis). They can be found in the demersal zones of rocky reefs, near the bottom and sediment.
Aulostomus maculatus inhabits the salty tropical waters of the western Atlantic Ocean, from Florida to Brazil, including the Caribbean islands and the Gulf of Mexico. Its preferred ecosystem is shallow waters from 2 to 25 meters deep and areas rich in corals, especially those with an abundance of vertical structures.
All signatiforms fish are characterized by elongated bodies surrounded by bony rings and very striking tubular mouths. The trumpet fish is no exception to this rule, which is why it is known by this common name.
The species Aulostomus maculatus is quite large, as it can reach 91 centimeters in length in its adult stage, somewhat longer than the rest of its relatives. Its body is elongated and very compressed on the sides and has an extremely long mouth, with a mandibular opening at the end. At the tip of the mouthparts there is a mustache or chin.
The dorsal and anal fins are small, reduced and are located far away from the cephalic plane of the fish, giving it an almost snake-shaped appearance. In addition, their coloration varies according to the individual and the location, but 3 specific patterns can be distinguished: red-brown -the most common-, gray-blue and yellow-greenish.
Behavior of trumpet fish
Strangely enough, trumpetfishes do not use the means of locomotion common to the vast majority of actinopterygian fishes. It is very rare to see a specimen swimming horizontally, as this species is “carried” by the current while maintaining an almost vertical position. While swimming, it places its head upside down and performs minimal movements.
In addition, as indicated by the PHYSIS Journal of Marine Science, the behavior of the specimens varies according to their general coloration pattern. For example, bluish individuals are found in deeper areas than yellowish or brownish ones. Body size is also different according to the general coloration.
A king of camouflage
Trumpet fish can use their chromatophores – cells with pigments inside that reflect light – to vary their overall hue and better mimic their surroundings. They are even able to mimic the movements of drifting seaweed while maintaining their upright position so as not to be detected by potential predators.
As they swim very poorly, these animals are completely dependent on their camouflaging abilities.
Feeding of trumpet fish
Fish belonging to the family Aulostomidae are exclusively carnivorous. They feed on invertebrates and small fish, but do not hunt or chase their prey. Due to their ability to emulate a vertical beam of algae, they wait for their victims to pass in front of them and catch them by suction mechanisms.
Thanks to the elastic tissues that make up its mouthparts, the trumpetfish can open the diameter of its mouth beyond the width of its own body. The rapid opening of this sophisticated mechanism generates a suction effect in the fish’s surroundings, thus drawing prey into its jaws.
These animals also hide behind some species of herbivorous fish. Thus, their prey are not able to see them until it is too late.
Reproduction of trumpet fish
The exact reproductive mechanism of trumpetfishes has not yet been elucidated, although it is known that males use their chromatophores to change color and exhibit courtship signals. In addition, this species -and the rest of the sagitiformes- presents a very atypical parental care format in the animal kingdom.
In this species, it is the male that takes care of the offspring. After external fertilization of the eggs laid by the female, he guards them in a special “pouch” until they hatch, taking care of them at all times. This evolutionary strategy has also been adopted by water dragons (Physignathus cocincinus) and seahorses (Hippocampus).
State of conservation
As indicated in the Red List of the International Union for Conservation of Nature (IUCN), the trumpet fish Aulostomus maculatus is not endangered, as it is included in the category of “Least Concern (LC)”. However, its populations are reported to be declining.
The global decline of kelp beds and corals could make the species’ long-term survival difficult. In addition, the spread of the lionfish (Pterois volitans) is a threat to this and many other actinopterygians. This is an invasive and lethal species that feeds on trumpet fish pups, among many other victims.
Although this species is not common in the aquarium world, sporadic thefts of specimens from the environment for lucrative purposes have been detected.
As you can see, the trumpet fish is one of the most fascinating actinopterygians in the world. Its way of reproducing, its hunting techniques and its excellent mimicry leave no one indifferent. Unfortunately, if the destruction of marine ecosystems continues at the current rate, it could be threatened in the not too distant future.