The results revealed that the water-flow velocity increased with increasing swimming speed during the underwater dolphin-kick lower-limb action, generating a strong vortex during the kicking action.

According to the organization, the fish is a so-called "black seadevil" known by its scientific name Melanocetus johnsonii. They typically swim between 650 and 6,500 feet below the ocean's surface.

Tsukuba, Japan—When humans kick swim through water, vortices form around their legs, generating the force that propels them forward. However, the mechanisms underlying variations in the ...