DIVE DRY WITH DR. BILL #798: SCRIBBLED OR SCRAWLED?
When the harsh winter winds blow and the water turns icy cold during winter here in southern California, I prefer heading to the tropics to dive. I grew up in Chicago where one day it hit 81° F below zero with the wind chill. Ever since that day, I've avoided even going into my kitchen freezer for food. Why tolerate water in the low 50s when I can spend a fortune (in marine biologist dollars) to fly to Palau, the Philippines, or even the Caribbean? At one point I even considered pursuing the endless summer by buying a bungalow in Cairns, Australia (back when the exchange rate was well in our favor).
There are many species of fish who are equally intelligent. Some such as the subject of this week's column are wise to live only in the tropics. I'm speaking of the scribbled or scrawled filefish (Aluterus scriptus). It is also known as the broomtail filefish, scrolled filefish, tobaccofish and scribbled leatherjacket. However, if you are Filipino you may call them tiwarik and if you are Hawaiian you may prefer loulu.
They are found in the warmer waters of the Pacific, Atlantic and Indian Oceans and I have filmed them in several places around the world. Scrawled filefish tend to prefer lagoons and reefs. Although generally seen in shallower waters, they may descend to depths of nearly 400 feet. At that depth I'm not sure I'd consider the waters very "tropical!"
This species has an elongated, oval-shaped and laterally compressed olive-brown or grey body that averages about two feet in length but can reach nearly twice that. Blue lines and spots decorate the body along with black spots on the anterior end. They are capable of changing color, often to better match their surroundings. The forward dorsal fin is modified into a fairly long, thin spine that can be erected. When threatened, they hide in crevices and raise the spine to anchor themselves just like their relatives the triggerfish. The tail fin is fan-like and fairly large. The scales are small and have spines making the skin rough to the touch which is the reason for the name filefish.
The mouth is fairly small. They chow down on small crustaceans, molluscs, tunicates, coral, sea anemones and gorgonians adding a bit of algae or seagrass for a healthy diet. In turn they are eaten by larger fish predators such as the dolphinfish and bluefin tuna. Although some consider them gamefish, they are not particularly good to eat (especially if I'm doing the cooking). One Internet site suggested these filefish were highly toxic with a poison (palytoxin) 70 times worse than fugu, a pufferfish considered a delicacy in Japan (when properly prepared). However, there are no recorded deaths from eating them.
Although Wikipedia states they are solitary and rarely seen with others, I have filmed pairs of them foraging in Palau. Perhaps it was mating season. After all, it does take two to tangle! Actually according to my research, they breed in small groups consisting of a single male and up to five females. Now that's what I call "tangling." The eggs are laid on the bottom, often in a depression in the sand. The male then fertilizes them and both mamma and papa guard the nest. After the eggs hatch, the female protects the young.
So how does this species establish itself over such a wide geography? I did not read anything that suggested their larvae have a long pelagic existence. However, Fishbase.com stated that the juveniles may travel with "weed" (algae?) rafts for a long time and reach a large size. My field research back in the 60s and 70s illustrated that some of our local fish can disperse across the Channel and up-and-down the mainland coast by following drifting kelp "rafts" so this was no surprise.
© 2019 Dr. Bill Bushing. For the entire archived set of nearly 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Scrawled filefish showing two color variations.
When the harsh winter winds blow and the water turns icy cold during winter here in southern California, I prefer heading to the tropics to dive. I grew up in Chicago where one day it hit 81° F below zero with the wind chill. Ever since that day, I've avoided even going into my kitchen freezer for food. Why tolerate water in the low 50s when I can spend a fortune (in marine biologist dollars) to fly to Palau, the Philippines, or even the Caribbean? At one point I even considered pursuing the endless summer by buying a bungalow in Cairns, Australia (back when the exchange rate was well in our favor).
There are many species of fish who are equally intelligent. Some such as the subject of this week's column are wise to live only in the tropics. I'm speaking of the scribbled or scrawled filefish (Aluterus scriptus). It is also known as the broomtail filefish, scrolled filefish, tobaccofish and scribbled leatherjacket. However, if you are Filipino you may call them tiwarik and if you are Hawaiian you may prefer loulu.
They are found in the warmer waters of the Pacific, Atlantic and Indian Oceans and I have filmed them in several places around the world. Scrawled filefish tend to prefer lagoons and reefs. Although generally seen in shallower waters, they may descend to depths of nearly 400 feet. At that depth I'm not sure I'd consider the waters very "tropical!"
This species has an elongated, oval-shaped and laterally compressed olive-brown or grey body that averages about two feet in length but can reach nearly twice that. Blue lines and spots decorate the body along with black spots on the anterior end. They are capable of changing color, often to better match their surroundings. The forward dorsal fin is modified into a fairly long, thin spine that can be erected. When threatened, they hide in crevices and raise the spine to anchor themselves just like their relatives the triggerfish. The tail fin is fan-like and fairly large. The scales are small and have spines making the skin rough to the touch which is the reason for the name filefish.
The mouth is fairly small. They chow down on small crustaceans, molluscs, tunicates, coral, sea anemones and gorgonians adding a bit of algae or seagrass for a healthy diet. In turn they are eaten by larger fish predators such as the dolphinfish and bluefin tuna. Although some consider them gamefish, they are not particularly good to eat (especially if I'm doing the cooking). One Internet site suggested these filefish were highly toxic with a poison (palytoxin) 70 times worse than fugu, a pufferfish considered a delicacy in Japan (when properly prepared). However, there are no recorded deaths from eating them.
Although Wikipedia states they are solitary and rarely seen with others, I have filmed pairs of them foraging in Palau. Perhaps it was mating season. After all, it does take two to tangle! Actually according to my research, they breed in small groups consisting of a single male and up to five females. Now that's what I call "tangling." The eggs are laid on the bottom, often in a depression in the sand. The male then fertilizes them and both mamma and papa guard the nest. After the eggs hatch, the female protects the young.
So how does this species establish itself over such a wide geography? I did not read anything that suggested their larvae have a long pelagic existence. However, Fishbase.com stated that the juveniles may travel with "weed" (algae?) rafts for a long time and reach a large size. My field research back in the 60s and 70s illustrated that some of our local fish can disperse across the Channel and up-and-down the mainland coast by following drifting kelp "rafts" so this was no surprise.
© 2019 Dr. Bill Bushing. For the entire archived set of nearly 800 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Scrawled filefish showing two color variations.
