dorsal fin

(redirected from Dorsal fin ray)
Also found in: Dictionary, Thesaurus, Encyclopedia.

dorsal fin

n.
One of one or more unpaired fins on the back of fishes and certain marine mammals.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

dorsal fin

any unpaired median fin on the backs of fishes and some other aquatic vertebrates. The fin maintains balance during locomotion.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Description: Dorsal fin rays IX, 11; anal fin rays 111,9; pectoral fin rays (including upper rudimentary ray) 14; pored lateral line scales 16 + 9 (one paratype with 15 + 6, and another with 16 + 7); scales above lateral line to origin of dorsal fin 2; scales below lateral line to origin of anal fin 6; median predorsal scales 5 (4-5); median preventral scales 6 (one paratype with 5); rows of scales on cheek 2; circumpeduncular scales 15 (15-16); gill rakers 13 (two paratypes with 14); pseudobranchs 13 (12-13).
octotaenia of the Red Sea, in having rounded dorsal, anal, and caudal fins, and lacking prolonged dorsal fin rays. The two species differ in total number of gill rakers on the first branchial arch (13-14 in P.
The present analysis also found differences in the mean numbers of dorsal fin rays, trunk rings and tail rings, as well as trunk and tail subdorsal rings, although the ranges of these counts always overlapped, in some cases greatly, between the two nominal taxa.
Diagnosis: Caudal fin deeply forked, lobes attenuate, filamentous, particularly in males; caudal concavity 23-32% SL; dorsal fin rays 16-18; dorsal fin origin anterior to upper end of gill opening; male with 2nd and 3rd dorsal fin spines elongated, flexible, with small fleshy tab at tip; 3rd dorsal fin spine elongated in adult female, rear end of fin rounded; anal fin angular, rays 7-8, 3rd to 5th rays elongated; pectoral fins rounded, rays 19-21, uppermost 1 or 2 rays unbranched; pelvic fins pointed.
Abbreviations in the table: SL = Standard length, BD = Depth at pelvic fins, PD = Predorsal length, PA = Preanal length, PP = Prepelvic length, CPL = Caudal peduncle length, CPD = Caudal peduncle depth, HL = Head length, SL = Snout length, ED = Eye diameter, D = number of dorsal fin rays, A = number of anal fin rays, LL = scales on lateral series.
Anal fin nearly uniform in height, rays slightly shorter than dorsal fin rays; base of anal fin 3.6 (3.3-3.6) in SL; origin of fin below base of first or second dorsal soft ray; two short anal spines, the first 1.4 (1.5-2.1) in length of second spine; all soft anal rays branched, becoming increasingly branched posteriorly, last ray branched at base; penultimate soft anal ray notably longer than adjacent rays, length 2.1 (1.7-2.2) in HL.
Dorsal fin rays with small melanophores (sometimes forming very thin continuous dark streak) along anterior and posterior margins of branched and unbranched portions, dorsal fin interradial margins otherwise without melanophores.

Full browser ?