taxonID	type	description	language	source
03D287D3FFA1FFB80E4AFADBFF2FB9B0.taxon	description	Four examples of backward swimming were observed (Table 1; Figure 2). At deployment 1, the eel was feeding on the seafloor with its head beneath the bait support arm of the lander whereupon it escaped backward over approximately two body lengths (Video S 1). It then turned to its left by bending the body and swam forward away from the lander. Figure 2 shows one cycle of the backward swimming wave propagating forward from the tail. The head oscillates from side to side over a large amplitude as exemplified by comparison of the image at 0.60 s with the start (0.00 s) and end (1.44 s) positions. At deployment 2, an individual reversed off the seafloor near the lander for four tail beats before bending its body toward the left to swim forward away from the lander (Video S 2). At deployment 3, after attempting to feed on the bait, the eel swam backward, ascending out of view of the camera (Video S 3). Possibly, a second species was observed at deployment 4, feeding at the bait and then departing backward for approximately two tail beats before turning by bending Ref Station Latitude Longitude Depth (m) Family Species Period (s) Hz λ (L) 1 TP 2 _ CR 6 _ 4500 0.818 144.303 4500 Synaphobranchidae Ilyophis robinsae 1.44 0.69 0.6 2 TP 2 _ MA 6 _ 4500 0.8005 144.299 4484 Synaphobranchidae I. robinsae 1.05 0.95 0.7 3 TP 2 _ OM 7 _ 4500 3.9307 144.032 4573 Synaphobranchidae I. robinsae - - 0.75 4 TP 3 _ OM 5 _ 4600 6.6435 156.932 4816 Synaphobranchidae Synaphobranchid 1.97 0.51 0.75 5 TP 1 _ OM 4 _ 5600 32.0665 148.769 5568 Macrouridae Coryphaenoides yaquinae 1.914 0.52 ≤ 0.5 6 TP 2 _ CR 7 _ 4500 3.925 144.014 4588 Macrouridae C. yaquinae 2.81 0.36 0.7 7 TP 2 _ MA 5 _ 4900 4.4823 145.883 4937 Macrouridae C. yaquinae 3.46 0.29 0.5 8 TP 4 _ OM 2 _ 5400 20.7042 146.272 5445 Macrouridae C. yaquinae 4.85 0.21 0.7 9 BH _ CL 4 _ 6300 25.142 136.395 6328 Ophidiidae Bassozetus sp. 5.55 0.18 ≤ 0.5 10 TP 2 _ CR 7 _ 4500 3.925 144.014 4588 Ophidiidae Bassozetus sp. - - ≤ 0.5 11 TP 2 _ OM 5 _ 4900 4.4873 145.866 4944 Ophidiidae Bassozetus sp. 11 0.09 - 12 TP 6 _ CR 5 _ 4500 4.6162 146.773 4465 Ophidiidae Bassozetus sp. 2.26 0.44 ≤ 0.5 13 TP 2 _ CR 6 _ 4500 0.818 144.303 4500 Ophidiidae Barathrites iris 3.27 0.31 0.7 14 TP 2 _ CR 6 _ 4500 0.818 144.303 4500 Ophidiidae B. iris 1.98 0.5 0.6 Note: Period, Hz, and λ refer to the observed backward swimming wave, where λ = wavelength expressed in terms of body length L. Abbreviations: Ref, reference number of the video; station, lander deployment code. its body in a C shape to the left and swimming away in a forward direction (Video S 4). Except in deployment 3, where the fish moved out of the field of view, the backward swimming was a short escape or departure maneuver over about two body lengths before the individual turned to swim forward away from the lander. With λ values of approximately 0.7, a complete propulsive wave was evident within the length of the fish.	en	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): 52-62, DOI: 10.1111/jfb.16049, URL: https://doi.org/10.1111/jfb.16049
03D287D3FFA0FFBF0D02F896FE28B99D.taxon	description	Four examples of backward swimming by C. yaquinae were observed. At deployment 5 (Figure 3) the nose of the fish was above the camera, and it swam backward for five tail beats, presenting a view of its ventral surface to the camera as it moved away into the center of the field of view (Video S 5). The pectoral fins executed a backward paddling motion, where the left and right fins were 180 out of phase with one another but in synchrony with tail beats (Figure 3). In contrast to the eel I. robinsae the head did not oscillate from side to side; in Figure 3, the tip of the nose follows the line marking the straight track between the start and end positions. After the backward escape maneuver, the fish turned to its right by bending the body in an arc and aided by a power stroke of the left pectoral fin continued swimming forward away from the lander. At deployment 6, the fish was below the camera and moved backward using both reverse body undulations and pectoral-fin motions, presenting its dorsal surface to the camera. Having completed the move away from the camera, it then began forward swimming toward the camera but used its pectoral fins as hydroplanes to ascend and pass safely above the camera (Video S 6). At deployment 7, the fish was trapped, upside down on the sediment beneath the bait retaining bars of the lander. It extricated itself by backward swimming with combined reverse body undulations and pectoral-fin paddling at the sediment interface. It then righted itself by bending the body in a tight “ C ” shape and, aided by movement of the pectoral fins, turned and straightened its body to swim forward away from the lander (Video S 7). At deployment 8, the fish was observed moving slowly backward aided by the bottom current passing waves along its body and paddling with the pectoral fins. After this backward excursion, it began swimming forward against the current (Video S 8). In all four cases, the macrourid used a reversed propulsive wave of the body and tail together with alternating paddling motions of the pectoral fins to swim backward away from the lander.	en	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): 52-62, DOI: 10.1111/jfb.16049, URL: https://doi.org/10.1111/jfb.16049
03D287D3FFA7FFBE0E4AF896FF06B9D7.taxon	description	Two instances of backward swimming were recorded. At deployment 13, the nose of the fish was under the bait from where it retreated by swimming backward for three tail beats, with synchronous movements of the pectoral fins before swimming forward after it had avoided the obstruction (Video S 13). At deployment 14, the fish swam backward, ascending from the seafloor using pectoral fin sculling and passing waves along the body (Figure 5) for three tail beats (Video S 14). Having completed its ascent, the fish resumed forward swimming. At 1.62 s (Figure 5) or 4 s into Video S 14, there was a possible suction feeding event, with movements of the jaws and opercular apparatus.	en	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): 52-62, DOI: 10.1111/jfb.16049, URL: https://doi.org/10.1111/jfb.16049
