anal fin

anal fin
the median ventral fin or fins behind the anus. Abbreviated as A, or A1 and A2 if there are two. Also called proctopterygium or proctal fin, it functions to maintain equilibrium against rolling

Dictionary of ichthyology. 2009.

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  • anal fin ray count — enumeration of the soft anal fin rays. In fishes where the smaller rays in front gradually grade into larger rays, these smaller anterior rays are included in the count, e.g. Ictaluridae, Esocidae, Gadidae. Where the first small rays abruptly… …   Dictionary of ichthyology

  • anal fin base length — the distance between the origin and the insertion of the anal fin, i.e. the length of that portion of the anal fin in contact with the body …   Dictionary of ichthyology

  • anal fin depressed length — the depressed length of the anal fin is the distance from the origin to the farthest posterior tip when the fin is flattened down …   Dictionary of ichthyology

  • anal fin — the median, unpaired fin on the ventral margin between the anus and the caudal fin in fishes. See diag. under fish. * * * …   Universalium

  • anal fin — /eɪnəl ˈfɪn/ (say aynuhl fin) noun (in fishes) the median ventral unpaired fin behind the anus …  

  • anal fin — noun in fishes : a median unpaired fin on the lower posterior part of the body behind the vent and sometimes confluent with the caudal fin see fish illustration …   Useful english dictionary

  • anal fin — noun A fin located on the underside of a fish behind the anus …   Wiktionary

  • anal fin — noun Zoology an unpaired fin located on the underside of a fish behind the anus …   English new terms dictionary

  • anal fin height — the distance from the origin to the tip of the longest ray. Sometimes taken as the greatest vertical height from the base …   Dictionary of ichthyology

  • Anal — A nal, a. [From {Anus}.] (Anat.) Pertaining to, or situated near, the anus; as, the anal fin or glands. [1913 Webster] …   The Collaborative International Dictionary of English

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