THINK ABOUT THE MOST RELENTLESS HUNTERS THAT MIGHT BE SEEN ON THE REEF and most divers would probably envision menacing sharks, barracudas and moray eels.
But those are mere grandstanders in the predation game. High on the list would have to be a species of singular fishes that Caribbean divers encounter so frequently – and that appear so benign – that they’re likely to take them for granted and ignore them.
After all, the ever-present trumpetfishes (Aulostomus maculatus) seem to spend most of their day just swaying along with the surge, their most noticeable trait being an insistence on hovering head-down in crowded places, like stands of rope sponges and sea plumes. They pose no threat to divers and in fact seem oblivious to them.
ACTUALLY, THEY’RE COMPLICATED
For one thing, trumpetfishes are sneaky, efficient predators, pretty nearly always on the hunt while seeming to be hanging around doing nothing.
They appear in varying colors but they’re all members of a single species. They’re masters of camouflage, able to blend in with their surrounding – see sea plumes and rope sponges, above.
They’re closely related to seahorses and pipefish, and they share those species’ trait of the males holding onto and hatching the eggs that produce new, little fishes.
Trumpetfishes do have closer cousins in the form of cornetfishes, less-common denizens of the tropical Atlantic & Caribbean, and “Chinese trumpetfishes,” found in the Indo-Pacific basin.
LONG BODIES, REALLY BIG MOUTHS
While a trumpetfish’s most obvious characteristic is a compressed, elongated body (up to 3 feet or more, according to some sources, although typically smaller), its most compelling feature is its upturned, flexible mouth at the end of its long, exaggerated snout. A trumpetfish’s head, adorned with a small barbell on its chin, represents a third of its overall length.
Like many fishes, when they open their mouths in pursuit of prey, trumpetfishes create a suction that sweeps the target in. In the trumpetfish’s case, elastic tissues enable it to widen its jaw to the diameter of its body – some sources say wider. All this is good: despite their prominent mouths, trumpetfishes don’t have any teeth on their upper jaws and only tiny teeth on their lower jaws.
While their stock in trade prey includes shrimps, copepods and small fishes like gobies, blennies and chromis, trumpetfishes are known to prey on larger game: they’ve been observed swallowing French grunts, ocean surgeonfishes, tomtates and longspine squirrelfishes. Turnabout is fair play: trumpetfishes themselves are commonly preyed upon by fishes like coneys, yellowfin groupers, red hinds, schoolmasters and moray eels.
Not surprisingly, trumpetfishes’ scientific name – Aulostomus maculatus – reflects their anatomy; “auls” is taken from Greek for “flute,” “stoma” from the Greek for “mouth.” Maculatis is taken from a Latin word for “spot,” referring to its adornment with irregular black spots.
ONE SPECIES, MULTIPLE COLORS
Most commonly, trumpetfishes display a mottled, reddish brown color, with silver or bluish streaks and black or brown spots along their bodies. But it’s not unusual to see bright yellow, blue-gray or green specimens. They’re all the same species. And they’re experts at camouflage, with an ability to lighten or darken their colors and manipulate silver and blue streaks along their bodies and black bars or spots on their fins.
Trumpetfishes also use color alterations as part of their courtship ritual, which involve elaborate dance-like maneuvering. Like their seahorse and pipefish cousins, they reproduce in a singular way: following their courtship dance high in the water column, the female transfers eggs to a pouch in the male’s body, in which he fertilizes and carries them until they are born (Note: one source contradicts this, asserting broadcast spawning near the surface, but several others agree on the pouch phenomenon).
HEAD DOWN, CUNNING
Trumpetfishes are often seen hovering head down in the water column, often lined up with masses of sea rods and plumes and rope sponges, often swaying in the current the way those structures do, seeking to blend in with the scenery. Sometimes they’re just head-down in open areas. They may seem indifferent – but they’re watching and waiting. When vulnerable small fish or crustacean is spotted, the trumpet-like jaws come into action, vacuuming the prey in.
Often, trumpetfishes are seen engaging in “shadow feeding,” disguising their shapes by swimming with herbaceous animals like princess parrotfishes, ready to strike any prey of opportunity. While trumpetfishes’ small fins don’t make them great long-distance swimmers, they can coil their bodies above their proxies and strike quickly.
At night, trumpetfishes tend to sleep in a vertical position, often lining themselves up with upright structures like sponges and gorgonians – and pier pilings.
Atlantic trumpetfishes are in the same order as seahorses and pipefishes – Order Syngnathiformes (which just means “conjoined jaws”) – but have closer relatives in the cornetfish and the “Chinese trumpetfish.” Worldwide, there are four species of cornetfish in the genus Fistularia. The Chinese trumpetfish is found throughout the Indo-Pacific basin. Atlantic trumpetfishes apparently evolved from their Pacific cousins about two million years ago, after the Isthmus of Panama arose to join North and South America together and created separate populations in the Atlantic and Pacific realms.
In the Pacific, the Chinese trumpetfish is known to be a predator of juvenile lionfishes, and some authorities express the hope that trumpetfishes in the Atlantic will adapt to this behavior and provide yet another bulwark against the invasive lionfish species.
Principal Sources: “Trumpetfish,” Florida Museum of Natural History, Ichthyology Department; “Trumpetfishes,” MarineBio.org; “Trumpetfish,” Lamar University Biology Department; “Trumpetfish,” “Cornetfish,” “Chinese Trumpetfish,” fishbase.org; “Trumpetfish,” oceana.org; “Trumpetfish,” Humann & DeLoach, “Reef Fish Identification.”