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Wednesday, Nov. 12, 2008

ANIMAL TRACKER

Thread-sail filefish


* Japanese name: Kawahagi
* Scientific name: Stephanolepis cirrhifer
* Description: From the side, filefish appear almost circular, with a large eye located high on the head, pouting lips and an elongated tail. From the front, however, they almost disappear, so thin is the body. This is where the common English name filefish comes from — along with the fact that the scales of the fish are so rough that dried specimens were sometimes used to sand wood. They have pale bodies with camouflage mottles, and they resemble the more famous pufferfish, to which they are related. There is a spine on the top of the head, visible in this photo, that scuba divers may have noticed on the head of the notorious trigger fish (another relative). There are good reasons not to put your finger in the mouth of a filefish: in the upper jaw there are two rows of teeth, an inner and outer series; in the lower jaw, there is one row.
* Where to find them: In the Pacific, from Tokyo Bay south to Kyushu and Okinawa, and in warmer parts of the Japan Sea. Filefish are found in lagoons, bays and shallow water, up to about 30 meters. If you look carefully while snorkeling, you might see filefish drifting, head downward, in seaweed. They are also found in tanks in sushi shops, and they are typically served sliced wafer-thin so the design of the ceramic can be seen through the flesh of the fish.
* Food: Small, bottom-dwelling invertebrates, such as sea squirts, sea fans and jellyfishlike colonial animals. Also algae and seagrass.
* Special features: The trigger on the head is a mechanism that helps protect against predators. When erect, it stops a bigger fish swallowing the filefish whole; likewise, the filefish can use the trigger to wedge itself in between rocks and prevent itself being pulled out — not much use in a tank in a sushi shop, but handy out in Tokyo Bay. The pelvis of the filefish is also adapted for antipredator defense. When threatened, the pelvis is expanded to help the fish jam itself in crevices. Filefish males help build nests for the females to spawn in, and they help guard the developing eggs and fry.

PHOTO COURTESY OF BIO-IMAGE NET



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