This video of a searobin using modified fins to move across the seafloor was collected during a 2017 American Samoa expedition dive within the Ta'u Unit of National Marine Sanctuary of American Samoa. It’s a fish out for a stroll!
Armored searobins are related to the searobins found in shallow water along the Atlantic and Gulf of Mexico coasts of the United States. They differ from shallow-water searobins by having four rows of bony plates along the body. Each plate has a thick, curved, short spine — hence the common name. They also have horn-like projections on each side of the snout and branched barbels (whiskers) on the bottom of the head, in front of the mouth. The branched barbels have taste buds and are used to sense food on the bottom.
The fan-like fins on each side of the body behind the head (pectoral fins) have stiffened rays. In searobins, including the armored searobin, the first few rays are free from the membranes of the rest of the fin and are very thick. The fish uses these thickened, stiff fin rays to "walk" along the bottom. That is the usual form of locomotion for searobins, instead of swimming like most other fishes.
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Video courtesy of NOAA Ocean Exploration, 2017 American Samoa.
Dive 02: Ta'u Unit of National Marine Sanctuary of American Samoa