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 species name is from the Latin flavus for yellow and lineatus, in reference to a line, for the most conspicuous colour marking, the yellow line passing from behind the eye to below the first dorsal fin.
Three broad vertical bands become apparent dorsally on the nape, below the center of the spinous dorsal fin and below the center of the soft dorsal fin by 13.
First dorsal-fin origin about equal with anal-fin origin; longest spines of first dorsal fin 1.
Caudal-fin base dark yellow, lobes hyaline; pectoral fin yellow with rays dark basally, pelvic fins hyaline, dorsal fin with dark bands extending on to rays, more pronounced on the tips.
Origin of first dorsal fin over inner base of pelvic fins, the predorsal length 3.
CP = caudal peduncle; horizontal distance from the posterior edge of the dorsal fin base to the posterior edge of the hypural plate.
First dorsal fin slightly shorter than second dorsal in adults and juveniles; depressed posterior rays of first dorsal fin extending slightly beyond origin of second dorsal fin in adults and about even with or just falling short of origin in specimens less than about 60 mm SL; depressed posterior rays of second dorsal fin extending about three-fourths length of caudal peduncle in large adults, but usually only half length of peduncle or less in smaller specimens; penultimate anal ray tallest, 16.
It is possible that some small dorsal fins may have been anal fins or second dorsal fins.
5 mm SL subadults); body depth at anus 10-11% SL; head length 30-33% SL; head width slightly greater than head depth; head depth 42-50% HL; snout length 25-30% HL; anterior and posterior nostrils absent; lower jaw slightly protruding; gill opening reaching anteroventrally to below between posterior half and end of preopercle; two curved canine tooth at mid-side of lower jaw; pelvic fins cup-like; pelvic frenum with anteriorly-facing pocket; caudal fin truncate; color in alcohol dull orange-red, grading to yellow posteriorly on caudal peduncle and base of caudal fin; snout and lips dull yellow; dorsal fins with whitish rays, transparent membranes, and yellow along the base; caudal and pectoral fins with light yellowish rays and translucent membranes.
reticulatus, by the position of the dorsal fin, which has its origin anterior to the origin of the anal fin in males, and by possessing the tips of both dorsal and anal-fins pointed in males, without elongated rays (vs.
The family Hemiscylliidae, commonly known as bamboo, epaulette, or walking sharks, contains small, slender sharks characterised by nasoral and perioral grooves, short barbels, a small transverse mouth below the eyes, two similar-sized dorsal fins, and a long slender tail.