Sideways Swimming Is More Efficient for Hammerhead Sharks

The technique may not look very graceful, but hammerhead sharks have a good reason for swimming on their sides: When moving through the water at an angle, the sharks reduce their energy expenditure by about 10 percent, New Scientist reports.

For a study recently published in the journal Nature Communications [PDF], researchers compared the locomotion of hammerheads to other shark species. All sharks have one dorsal fin on their backs that acts as a rudder and two pectoral fins spanning out from their sides to keep them afloat. Hammerheads share these traits, but unlike other shark species, they use them a bit differently.

Most sharks have pectoral fins that are longer than their dorsal fins, but for hammerheads it’s the reverse. When they turn their bodies sideways their dorsal fin acts as a pectoral fin replacement, effectively elongating their “wingspan” and making them better swimmers.

The sharks can be seen taking advantage of this trick quite often. After attaching cameras and accelerometers to five hammerheads, the researchers found that they spent 90 percent of their time swimming at roll angles of 50° to 75°.

You can see some examples of the species’s goofy swimming style in the video below. For a look at the ocean from their tilted point of view, check out this Go-Pro footage recorded from the perspective of a hammerhead dorsal fin.

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