Anatomy of finfish and shellfish

Unit – 3 Study of oral region and Associated structures

3.3.2. Teeth
Outstanding among the obvious oral adaptation for feeding in fishes are the teeth. They are thought to have arisen from scales covering the lips, as represented in living sharks (squliformies) where the placoid scales of the skin visibly grade into teeth on the jaws.
In bony fishes (Osteichthyes) Teeth are of three kinds, based on where they are found Jaw, Mouth and Pharyngeal.
Jaw Teeth
Jaw teeth are variously those on the maxillary and premaxillary bones above and on the dentaries below.
In the roof of the oral cavity teeth are variously borne by the median vomer and by the palatine and ectopterygoid bones on each side. In the floor of the mouth the tongue often has teeth on it. Pharyngeal teeth occur as pads on various gill arch eolements in many species. In the carps (cyprinedae) and suckers (cjcatastromidae) the only teeth are those in deep in the pharynx (gut, mouth and eoesophagous) that develoed modification of lower elements after last gill arch, in clarius and labeo the teeth are modified for grasping, tearing, grinding and razor like cutting teeth have developed in predacious fishes.
Kinds of jaw teeth
Based on their form major kinds of Jaw teeth are
1) Cardiform 2) Villiform 3) Canine 4) Incisor and 5) Molariform.
Cardiform Teeth
Cardiform teeth are numerous, shrotfine and pointed such dentition with variations is found in many fishes that have multiple rowed teeth. For example American catfish (Ictaluridae) perches (percidae) and many sea bases (serranidae)
Villiform teeth
Villiform teeth are more or less elongated cardiform teeth. For example : Needlefishes (Belonidae) and Lion fishes as (Pterois).
Canine teeth
Canines are dog tooth like or fange like (long pointed tooth) they are elongated and subconical, straight or curved and are adapted for piercing and hodling for example walleyes (Alska pollock) (Stizostediosn). In certain fishes such as moreys (muraenidae) the canines are hinged (the hook) yield ot backward pressure but lock when moved forward and adaptation to retain living moving prey inside the mouth.
Incisors teeth
Incisors are sharp edged cutting teeth. In some fishes incisors fuse together in cutting beak as in parrot fishes (scaridae).
Molariform teeth
Molariform teeth are for crushing and grinding thus flat with prodruding denticles on the surface. These teeth are found in bottom dwelling fishes like skates and rays and some sciaenidae (drums).
With in a single group the diversity of dentition on identical bones may vary largely. For example In carps and minnows (cyprinidae) the pharyngeal teeth range from sharp in carnivores such as in semotilus to molariform in the common carp (Cyprinus carpio).
In general teeth are absent in plankton feeders and in some of the more generalized omnivore. They are present in increasing numbers of bones in more and more relative to its predatory behaviors. The premaxillary bones are toothed when jaw bones have little or no teeth. This is true for many soft rayed species such as bowfin (Amia) the gars (lepisosteus) the salmons and trouts (Salmonidae).
The maxillae are typically toothed in those soft rayed fishes as that carry premaxillary teeth. However tooth less in otherwise tooth – bearing spiny rayed fishes.