Swordfish are among the fastest fish on Earth, propelling themselves at speeds exceeding 60 miles an hour. A study published in July 2016 in the Journal of Experimental Biology gives partial credit for swordfish swiftness to a newly discovered organ. As it turns out, a gland that pumps lubricating oil throughout the skin makes it easier for the iconic predator to glide through the water.
Located just behind the swordfish bill, this oil gland produces fatty acids that flow through pores and capillaries, creating a layer of oil that repels water as the fish swims. This creates a smooth, liquid-impregnated surface, reducing drag by up to 20 percent and increasing swimming speed. Swordfish do not survive in captivity and are hard to track in the open ocean. To conduct their study, researchers used MRI scans, locating the denticles around pore openings and capillaries that transported oil. They also injected ink into a fish they dissected to trace connections between capillaries and pores and stimulated the gland with heat to observe oil flow.
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Swordfish are opportunistic predators, feeding near the surface and in deep water on fish, squid, and cuttlefish. When they dive deep into cold water, a special cluster of tissue attached to their eye muscles acts as a heater, warming and insulating their brains. Because adult swordfish have no teeth, they eat their prey whole after striking or slashing it with their bills. The lubricating gland gives them an advantage, enabling them to swim faster than the prey that they hunt.
The leader of the swordfish study marveled that researchers took so long to discover such an amazing speed enhancer. This highlights the fact that there are many more surprises left in the natural world for diligent investigators. For another amazing fish story, watch this video to find out how fish manage to swim in harmony.Whizzco