Glossary

dorsal-fin

Median, rayed, unpaired fin located on the dorsal surface (back) of most fishes. Its main purpose is to prevent the animal rolling and enable it to turn sharply. Some species possess more than one dorsal fin, in which case the anterior one is referred to as the first.

Used in 870 species profiles

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Related terms

adipose-fin
A small, fleshy, rayless fin present in certain fishes and located behind the dorsal fin.
anterior
Located near or towards the head; forward in position.
body depth
The vertical distance between the dorsal and ventral margins of the body measured at the base of the pectoral fin where it joins the body. In most icthyological works the greatest dimension, normally anterior to the dorsal fin, is taken but in some cases body depth is measured at the origin of pectoral, pelvic and first anal. Fins or fin bases are not included in the measurement, however.
dorsum
The upper surface of the head, body or part.
interdorsal
In species possessing more than a single dorsal fin, the space between the first and second fins.
medial
Relating to, situated on or in, or extending towards the middle; median. Opposite of lateral.
nape
In fishes, the part of the dorsal surface between the posterior edge of the skull and dorsal fin insertion.
postdorsal
Located posterior to the dorsal fin.
postdorsal length
The distance between the dorsal fin insertion/origin and caudal fin base.
predorsal
Area or region anterior to the first dorsal fin.
predorsal length
Distance between the tip of the upper jaw and inseryion/origin of first dorsal fin..
predorsal scale
Any of the scales lying on the dorsal midline between the back of the skull and insertion/origin of the dorsal fin.

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