DIVE DRY WITH DR. BILL #824: DON'T TRIGGER THESE FISH!
My video about the fish I saw in the Philippines is nearing completion. Looking over the 4+ hours of video I shot of them brings back many pleasant memories. However, one fish encounter was not to pleasant. I'm referring to the time(s) I've been attacked by the Titan triggerfish (Balistoides viridescens) or its relative, the yellow margin trigger (Pseudobalistes flavimarginatus).
When I dove in Tahiti years ago, I learned the Tahitians feared these fish more than sharks. I soon learned why! They form nests in the sandy bottom, but defend an ever-widening cone above the nest all the way to the surface. You could be swimming 20 feet above the nest and enter that cone, "triggering" an attack. And as you can see from the dried specimen I photographed in Puerto Galera, PI, their teeth are formidable! If you ever encounter one, swim horizontally to get out of the cone rather than toward the surface where the cone is largest.
It is good to be aware of the Titan's threat posture and potential pre-attack behavior. They will face a diver with their first dorsal spine erect. They may also roll on their side to get a better look at you. If so, my advice (sir) is to move on!
Titan triggers have large scales that appear cross-hatched on the body. Their dorsal and anal fins have black margins vs the yellow margins of the aptly named yellow margin trigger. Some call it the moustache trigger due to the dark band above the thick lips. The head region is lighter in color and slightly yellow. Toward the rear before the tail there is a white region. The tail is yellow with a dark band at the base and margin.
The Titan trigger is circumtropical. It may reach a length of nearly 30 inches, making it the second largest species of triggerfish. They feed on sea urchins and crustaceans such as crabs and molluscs. Occasionally they'll take a nip of a diver's fin... or a bit of flesh. However that is "merely" a defensive move rather than gustatorial. I guess we deserve it since triggers are sometimes caught and offered in markets either fresh or salted. However, its flesh may contain ciguatoxin which is a toxin produced by dinoflagellates but biomagnified up the food chain.
When I was attacked by Titans, they nipped at my fins. I tried to escape by back kicking as hard as possible, which seemed to aggravate them but also helped me escape the defense cone. Attacks by yellow margin triggers were similar, but often stopped short of actual contact. They would swim rapidly up close to me and then retreat back to their nest, often repeating this a number of times.
The yellow margin triggers look superficially similar to Titans. Only the keen eye of this trained marine biologist can tell the difference, especially when trying to escape an attack! This species lacks the Titan's moustache. The body past the pectoral fin has large scales similar to the Titan but they extend all the way to the base of the tail. The tail is dark and lacks the bright yellow color of the Titan's. As indicated by the name, their dorsal and ventral fins have yellow margins rather than black.
Yellow margin males apparently establish the nest in the sand at established spawning areas. The ladies get to choose their mate, perhaps on Sadie Hawkins Day. Hmmm, I wonder if that reference is too dated for my younger readers! Although both male and female will guard the nest, only the female tends the eggs. Fishbase stated that up to 430,000 eggs may be laid. I wonder who did the counting and how many times they were attacked while doing so!
© 2019 Dr. Bill Bushing. For the entire archived set of over 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Dried Titan triggerfish in Puerto Galera and Titan feeding; Titan being cleaned by wrasse and yellow margin trigger, attack by a yellow margin trigger.
My video about the fish I saw in the Philippines is nearing completion. Looking over the 4+ hours of video I shot of them brings back many pleasant memories. However, one fish encounter was not to pleasant. I'm referring to the time(s) I've been attacked by the Titan triggerfish (Balistoides viridescens) or its relative, the yellow margin trigger (Pseudobalistes flavimarginatus).
When I dove in Tahiti years ago, I learned the Tahitians feared these fish more than sharks. I soon learned why! They form nests in the sandy bottom, but defend an ever-widening cone above the nest all the way to the surface. You could be swimming 20 feet above the nest and enter that cone, "triggering" an attack. And as you can see from the dried specimen I photographed in Puerto Galera, PI, their teeth are formidable! If you ever encounter one, swim horizontally to get out of the cone rather than toward the surface where the cone is largest.
It is good to be aware of the Titan's threat posture and potential pre-attack behavior. They will face a diver with their first dorsal spine erect. They may also roll on their side to get a better look at you. If so, my advice (sir) is to move on!
Titan triggers have large scales that appear cross-hatched on the body. Their dorsal and anal fins have black margins vs the yellow margins of the aptly named yellow margin trigger. Some call it the moustache trigger due to the dark band above the thick lips. The head region is lighter in color and slightly yellow. Toward the rear before the tail there is a white region. The tail is yellow with a dark band at the base and margin.
The Titan trigger is circumtropical. It may reach a length of nearly 30 inches, making it the second largest species of triggerfish. They feed on sea urchins and crustaceans such as crabs and molluscs. Occasionally they'll take a nip of a diver's fin... or a bit of flesh. However that is "merely" a defensive move rather than gustatorial. I guess we deserve it since triggers are sometimes caught and offered in markets either fresh or salted. However, its flesh may contain ciguatoxin which is a toxin produced by dinoflagellates but biomagnified up the food chain.
When I was attacked by Titans, they nipped at my fins. I tried to escape by back kicking as hard as possible, which seemed to aggravate them but also helped me escape the defense cone. Attacks by yellow margin triggers were similar, but often stopped short of actual contact. They would swim rapidly up close to me and then retreat back to their nest, often repeating this a number of times.
The yellow margin triggers look superficially similar to Titans. Only the keen eye of this trained marine biologist can tell the difference, especially when trying to escape an attack! This species lacks the Titan's moustache. The body past the pectoral fin has large scales similar to the Titan but they extend all the way to the base of the tail. The tail is dark and lacks the bright yellow color of the Titan's. As indicated by the name, their dorsal and ventral fins have yellow margins rather than black.
Yellow margin males apparently establish the nest in the sand at established spawning areas. The ladies get to choose their mate, perhaps on Sadie Hawkins Day. Hmmm, I wonder if that reference is too dated for my younger readers! Although both male and female will guard the nest, only the female tends the eggs. Fishbase stated that up to 430,000 eggs may be laid. I wonder who did the counting and how many times they were attacked while doing so!
© 2019 Dr. Bill Bushing. For the entire archived set of over 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Dried Titan triggerfish in Puerto Galera and Titan feeding; Titan being cleaned by wrasse and yellow margin trigger, attack by a yellow margin trigger.
