Presence of repeating hyperostotic bones in dorsal pterygiophores of the oarfish, Regalecus russellii

Abstract

Hyperostosis, excessive bone growth along bone that stems from bone, periosteum or articular or epiphyseal cartilage, occurs in at least 22 families of fishes most of which are tropical or subtropical marine species. While the presence of hyperostosis is well documented in fishes, the mechanism driving the development of the excessive bone growth is unclear. This study documented hyperostosis along the dorsal pterygiophores in both sexes of oarfish, Regalecus russellii; however, it was not present in all specimens examined. This is the second lampridiform fish with hyperostoses and the first case documented in a deeper-water, epi-mesopelagic fish. In oarfish, the majority of the dorsal pterygiophores tissues are poorly mineralized, anosteocytic bones with some fish displaying localized stiffened, hyperostotic growths near the distal edge. Oarfish lack a swim bladder so they must continuously beat their bi-directional dorsal fin to maintain position within the water column while engaged in locomotory behavior. These fishes have areas of localized, hyperostotic skeletal elements along the dorsal pterygiophores that, presumably, function as a stiffened lever system to support fin undulation. It was noted that hyperossification was not present in all fish examined and was only documented in fish with total lengths greater than 3 m.

The effect of feeding commercial diets on the development of juvenile crucian carp (Carassius carassius, L.). Part 1: Skeletal deformations

“…Anomalous pterygiophores were found in connection with a variety of disorders, including hyperostosis (Paig‐Tran, Barrios, & Ferry, ) or parasitic infection (Cunningham, Markle, Watral, Kent, & Curtis, ). However, they appear most frequently in cases of the “saddleback syndrome,” which is a partial or total absence of the dorsal or anal fin (Fragkoulis et al., ; Koumoundouros, Divanach, & Kentouri, ).…”

The phylogenetic origin and evolution of acellular bone in teleost fishes: insights into osteocyte function in bone metabolism

“…However these results are seemingly contradicted by more recent data (Sire & Meunier, 2017): at least in the case of Sparus aurata these tubules do not appear to contain osteocyte nuclei. In the second case, osteocytes were described within areas of hyperostosis in the cleithrum of the jack Caranx latus (Smith-Vaniz et al, 1995) and in dorsal pterygiophores of the oarfish Regalecus russellii (Paig-Tran, Barrios & Ferry, 2016), two acanthomorphs that otherwise have acellular bone. However, such osteocytes do not appear to be present systematically in acanthomorph hyperostotic bone: they are absent from the hyperostoses of the scabbardfish Trichiurus lepturus, the jack mackerel Trachurus trachurus, the sicklefish Drepane africana, the grunt Pomadasys kaakan and the searobin Prionotus stephanophrys (Desse et al, 1981;Meunier & Desse, 1994;Meunier, Béarez & Francillon-Vieillot, 1999;Meunier, Gaudant & Bonelli, 2010).…”

“…5A, E). Within lampridiforms, acellular bone has been described in the ribbonfishes Trachipterus trachypterus and Zu cristatus (Kölliker, 1859), in the oarfish Regalecus russelii (Paig-Tran et al, 2016) and in the veliferid Velifer hypselopterus (Davesne et al, 2018). Our SRµCT data show that the veliferid Metavelifer multiradiatus also lacks osteocytes (Table 1), and veliferids are probably sister to all other lampridiforms (Olney, Johnson & Baldwin, 1993;Wiley, Johnson & Dimmick, 1998;Davesne et al, 2014).…”

The phylogenetic origin and evolution of acellular bone in teleost fishes: insights into osteocyte function in bone metabolism

“…In the second case, osteocytes were described within areas of hyperostosis in the cleithrum of the jack Caranx latus (Smith‐Vaniz et al , ) and in dorsal pterygiophores of the oarfish Regalecus russellii (Paig‐Tran et al , ), two acanthomorphs that otherwise have acellular bone. However, such osteocytes do not appear to be present systematically in acanthomorph hyperostotic bone: they are absent from the hyperostoses of the scabbardfish Trichiurus lepturus , the jack mackerel Trachurus trachurus , the sicklefish Drepane africana , the grunt Pomadasys kaakan and the searobin Prionotus stephanophrys (Desse et al , ; Meunier & Desse, ; Meunier, Béarez & Francillon‐Vieillot, ; Meunier, Gaudant & Bonelli, ).…”

“…Within lampridiforms, acellular bone has been described in the ribbonfishes Trachipterus trachypterus and Zu cristatus (Kölliker, ), in the oarfish Regalecus russelii (Paig‐Tran et al , ) and in the veliferid Velifer hypselopterus (Davesne et al , ). Our SRμCT data show that the veliferid Metavelifer multiradiatus also lacks osteocytes (Table ), and veliferids are probably sister to all other lampridiforms (Olney, Johnson & Baldwin, ; Wiley, Johnson & Dimmick, ; Davesne et al , 2014).…”