Ophidiidae, Rafinesque, 1810

Priede, Imants G. & Jamieson, Alan J., 2025, Backward swimming in elongated-bodied abyssal demersal fishes: Synaphobranchidae, Macrouridae, and Ophidiidae, Journal of Fish Biology 107 (1), pp. 52-62 : 56

3.3 | Ophidiidae : Bassozetus sp.

Four examples of backward swimming by the cusk-eel Bassozetus were recorded. At deployment 9, the fish was beneath the camera and retreated swimming backward into the center of the field of view (Video S9). The dorsal view along the body shows propagation of the propulsive wave forward along the body (Figure 4). Synchronous paddling of the pectoral fins alternating side to side could be seen when the whole fish came into view. Once it had retreated, it resumed forward swimming in a slightly different direction, avoiding the camera.

At deployment 10, the fish encountered the camera on its left side and swam backward away from the camera before turning by bending the body to swim forward in a new direction (Video S10). At deployment 11, the fish was close below the camera, moving backward with the aid of slow pectoral fin paddling before turning by bending the body (Video S11). At deployment 12, the fish was above the camera, and backward swimming motion was clear in the shadow cast on the seafloor. After seven tail beats, the fish came into the field of view and then bent the body to the left to swim forward in a new direction. The pectoral fins paddled alternating side to side in synchrony with the body propulsive wave (Video S12).