A scientist from the Groningen & Leiden University discovered that swordfish swim fast due to self-lubrication. The oil is produced by a giant gland situated in their heads, allowing them to glide through currents without experiencing any friction.
John Videler has been studying the mechanics of swimming his entire career. Swordfish presented a particular challenge seeing as they are among the fastest swimmers in the ocean. Commonly, a swordfish specimen can reach 62 miles per hours (100 kilometers per hour).
Back in 1994, the researcher was a diving instructor in Corsica. He then bought a swordfish bill from a local tradesperson and started experimenting with it.
When a swordfish reaches high speeds, lots of water layers flow along its bill. As the speed increases, the currents can break away, giving birth to turbulences that drag the fish.
Videler observed that a swordfish’s bill is rough. This limits the exposure to turbulences to a thin area located near the bill. This physical feature is also filled with interconnected holes which are meant to stop the formation of water pressure near the front end of the fish.
In order to learn more about the anatomy of the swordfish, Videler convinced Ben Szabo, the radiology head at the University of Groningen, to put a specimen in the MRI scanner.
The images thus obtained were heard to interpret. However, when Videler dissected the scanned specimens he noticed that they all had a large oily gland between their eyes.
Until 2005 when a student of his expressed an interest in the anatomy of swordfish, Videler forgot about the subject. This was mostly due to his frustration of not figuring out the reason that the gland served.
However, one night when he was photographing the said gland, he dropped a heated light bulb on it. When the heated object touched the gland, the researcher was able to see a web formed of minuscule blood vessels that connected the anatomic particularity to the skin of the animal.
Keeping the unconventional touch, Videler then brought a hair dryer and heated the dissected animal finding that the vessels opened out into the fish’s pores. He reached this conclusion after the previously congealed oil started oozing out of the fish’s pores.
The scientists then put two and two together and realized that swordfish swim fast due to self-lubrication, the gland playing an important part in keeping the animal hydrodynamic.
Image source: Wikipedia