Meeting Abstract

65.2  Jan. 7  Specializations for gill rigidity in ram ventilating teleosts WEGNER, N.C.*; SEPULVEDA, C.A.; GRAHAM, J.B.; Scripps Institution of Oceanography; Pfleger Institute of Environmental Research; Scripps Institution of Oceanography nwegner@ucsd.edu

For ram-gill ventilators such as tunas (family Scombridae) and marlins (family Istiophoridae), a rigid gill structure prevents filament and lamellar deformation by the fast, continuous ventilatory flow stream. Comparative studies of water-flow resistance imposed by fusions binding the gill filaments and lamellae are in progress. In tunas, lamellar fusions bind adjacent lamellae on the same filament to opposing lamellae of the neighboring filament. Examination of other scombroid genera reveals lamellar fusions in the bonitos and a previously undescribed inter-lamellar fusion in the wahoo (Acanthocybium solandri), striped marlin (Tetrapturus audax), and sailfish (Istiophorus platypterus). Unlike lamellar fusions, the inter-lamellar fusion binds juxtaposed lamellae on the same filament, but does not connect to the opposing lamellae of the adjacent filament. This shared character in the wahoo, striped marlin, and sailfish supports the phylogenic hypothesis of Johnson (1986) who proposed that the billfishes are sister group to Acanthocybium.