dorsal fin

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dorsal fin

[′dȯr·səl ′fin]
(vertebrate zoology)
A median longitudinal vertical fin on the dorsal aspect of a fish or other aquatic vertebrate.

dorsal fin

dorsal fin
An additional fin surface along the top of the fuselage just in front of the main fin. Dorsal fins help increase directional stability, especially at high air speeds and Mach numbers.
References in periodicals archive ?
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.
affinis; dorsal fin rays ranging from 25 - 37 in S.
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.
Diagnosis: Caudal fin emarginate, lobes not filamentous; caudal concavity 6-17% SL; dorsal fin rays 16; 3rd to 10th dorsal fin spines subequal; anal fin pointed, rays 7-8; 2nd to 4th rays elongated; pectoral fins rounded, rays 17-18, pelvic fins angular, reaching just past anus; lateral line scales 43-47; scale rows from 5th dorsal fin spine to lateral line 3 or 4; circumpeduncular scales 26-28; head with small auxiliary scales; proximal half of median fins scaly, but spinous dorsal fin naked.
Diagnosis: Caudal fin emarginate in male, lobe tips bluntly pointed; rear margin slightly concave or slightly forked in female, caudal concavity 7-12% SL; dorsal fin rays 15-17; interspinous membranes slightly incised; no elongated spines; rear end of fin pointed; anal fin rays 6-8; fin of male enlarged and pointed from elongated middle rays; pectoral fins pointed, rays 16-19, middle rays longest reaching vertical at anus; pelvic fins rounded, reaching anus.
Diagnosis: Caudal fin crescentic; 29-36% SL; caudal concavity 12-29% SL; dorsal fin rays 15-17, no elongated spines or rays, but interspinous membranes produced as short filament behind tip of each spine; anal fin rays 7 (one of 15 fish with 6 anal fin rays); pectoral fin pointed, reaching 3rd anal fin spine, rays 17-19; pelvic fin 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.
Counts for dorsal fin rays (X or XI,21-23), anal fin rays (II,18-20), pectoral fin rays (15-17), gill rakers on the first branchial arch (4-6 + 11-12), pored lateral line scales (95-106), scales in lateral series (115-130), predorsal scales (33-40) and preopercle serrae (29-44) were generally similar and overlapping.
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.