The papilla, in certain kinds of
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...
, particularly
rays,
shark
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...
s, and
catfish
Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive ...
, are small lumps of dermal tissue found in the mouth, where they are "distributed uniformly on the tongue, palate, and pharynx".
[B. G. Kapoor, H. E. Evans, E. A. Pevzner "The gustatory system in fish" in ''Advances in Marine Biology, Volume 13'' (1976), F. S. Russell, Maurice Yonge (eds).] They "project slightly above the surrounding multi-layered
epithelium", and the taste buds of the fish are "situated along the crest or at the apex of the papillae".
Unlike humans, fish have little or nothing in the way of a
tongue
The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by taste ...
, and those that have such an organ do not use it for tasting, but merely for cushioning the mouth and manipulating things within it. The papillae of the fish, and the taste buds found on them, are therefore located on the interior or exterior surfaces of the mouth.
[Robert Bentley Todd, ''The Cyclopaedia of Anatomy and Physiology: Volume 1'' (1836), p. 532.] Most typically, these are found on the floor of the mouth, or on the upper lip.
References
{{diversity of fish
Fish anatomy