Swordfish are some of the most notoriously fast creatures in the ocean. In fact, they can allegedly reach up to 60 miles per hour. Which, for a fish, is pretty darn impressive. But, although this is undoubtedly one of the most-recognizable fish, on menus and in the sea alike, parts of their being are still a bit alien to us.
Cue John Videler, of Leiden & Groningen University, who has studied the physics behind swimming fish for much of his career. Swordfish have always been of interest to him, not just because of their quickness, but also because they are great swimmers.
Their efficiency is largely due to the ingenious design of their bill. Basically, when swordfish swim layers of water flow along the surface of its bill. However, the faster it gets the currents that are made by these layer can create drag. The bill, once doused in oil, is also porous and rough to further limit turbulence and decrease drag.
What else did John Videler and other researchers discover? Well, that there is a baseball-sized gland in their heads with slathers lubricating oils all their heads to help further increase their speed and is another drag-reducing aspect of swordfish.
The oil production also explain another quirky feature of the swordfish - they are one of the only fish with a "concave hollow at the front of their heads an slight inward-curving bowl that, counter-intuitively, ought to increase drag," according to National Geographic writer, Ed Young. Videler believes that this hollow is in fact shaped so that the water that zips by is create an area of low pressure, allowing the oil to be sucked out of the gland and then coat the bill.
Although this is an interesting theory, it is important to note it is still a working theory. Videler intends to conduct more experiments to further prove this idea.
The above image is from Flickr User Jocelyn Kinghorn is not related to the story. It is licensed under creative commons 2.0.