Trumpetfish adapt well to life on a shallow reef due to their ability to change color and pattern as well as their numerous hunting techniques. Its hunting methods allow it to be as close as possible to its prey and still escape detection. Divers can closely observe these fish while snorkeling.
Trumpetfish (Aulostomus maculatus) are some of the coral reef’s most frequently encountered residents. They are fascinating to study, owing to their remarkable behavior and color changes. Thefishes’ odd shaped bodies, two to three feet long, are one of nature’s most successful adaptations for life on a shallow reef. Their behavior and interaction with other fish may seem confused or comical – but you are observing some of the reef’s most effective predators.
During a snorkeling expedition, you will usually find the slender, thin bodied Trumpetfish in three different places: hiding among gorgonians or seawhips, usually head down; swimming alone or just above and parallel to larger fish, such as groupers; or swimming in a school of smaller fish, such as Blue Tangs or Surgeonfish.
Trumpetfish have the ability to change color and pattern to blend into their surroundings, whether this is a stand of gorgonians or a school of fish. You will see Trumpetfish in a range of hues – reddish browns, with pale silver lines and small black dots; purple/deep blues; brilliant yellows; and a few colors in between. These fish eat small fish and shrimp. Trumpetfish are ambush predators, sneaking up on their prey and darting in at the last minute.
The elongated snout of the Trumpetfish (the reason for its name) appears narrow but is capable of great expansion, giving it the capability of ingesting three to four inch wide fish. When the jaw opens, it creates a vacuum, literally sucking the prey in! This action takes place very quickly but, if you’re patient and stay about four to five feet away, you can easily observe the sharp, darting motion, which indicates another successful catch for this predator.
The Trumpetfish’s hunting techniques get it as close as possible to its prey without being detected. When hovering vertically in the seafans, searods and other gorgonians, it is either waiting in ambush for unsuspecting shrimp or hiding from predators. Indeed, if a snorkeler swims too close or approaches too quickly, the Trumpetfish will usually find the nearest gorgonian and hide. If hovering horizontally over the reef, in a small school of fish (always herbivores, so its prey is unsuspecting) or riding “piggyback” above a larger fish (some people mistakenly think the fish are courting), it’s usually hunting.
All residents of coral reefs have developed elaborate defense mechanisms to ensure their survival. Their eyes easily differentiate color and always identify the fish that approach their territories. Indeed, the elaborate coloration of reef fish and the unbelievable colors of the coral reef are all part of a grand, evolutionary plan. Small reef fish instinctively know they have nothing to fear from Blue Tangs, Doctorfish and Ocean Surgeonfish, owing to their herbivorous nature. If the Trumpetfish was to approach its prey alone, it would be recognized and the fish would disappear into coral nooks where the Trumpetfish can’t get at them. But, among a school of Blue Tangs the Trumpetfish can select its meal and make its move – a fascinating process that is easy to watch!
Trumpetfish reproduction occurs at dusk, as with most reef fish, but has not been widely studied. Dr. Ron Thresher, in Reproduction In Reef Fishes, reports an incident involving a female with distended abdomen being chased at dusk by two males. After a short period, the female made her selection, rose off the reef and began to deposit her eggs in open water. The chosen male followed and fertilized the eggs, which would then drift for several days before hatching. This is fairly typical of all reef fish; dusk is the time to observe both mating and reproduction on a coral reef.
Trumpetfish, although often viewed as reef comics and confused suitors, are actually highly effective predators. With an outstanding ability to change color and many different methods of hunting, they are uniquely adapted to the world they inhabit. Trumpetfish are among the easiest fish to closely observe while snorkeling. And, they will open your eyes to the complexity of life on a shallow reef.