3 Basic Terms Used for Feeding Mechanisms of Vertebrates 1. Suspension-feeding (= filter-feeding) - filter small particles (alive or dead, depending on species) out of water column2. Suction-feeding - open mouth, suck in food3. Ram-feeding - open mouth, swim over foodRam-Suction Index - compares movement of food relative to movement of feeder4. Inertial-feeding - inertia of food is used to move it in oral cavity5. Transport - movement of food within oral cavity (by water currents in aquatic vertebrates or tongue in tetrapods)6. Mastication - physical reduction of food size by chewing
5 Wear Patterns of Teeth are Functionally Important Enamel is > 95% inorganic matter; it is the hardest substance in vertebrate bodiesEnamel is harder than dentineDentine is harder than cementThese properties mean that teeth can be “self-sharpening”
6 Some Important Terms for Teeth Polyphyodont - multiple generations of tooth replacement (most vertebrates)Diphyodont - two sets of teeth: milk and permanent (most mammals; incisor, canine and premolar teeth are replaced)Monophyodont - a single set of teeth (e.g., cetaceans)Homodont - teeth of similar shape along jawHeterodont - teeth of different shape along the jawTooth plate or Toothplate - at least two uses are common:1. Many individual teeth fused together at their bases; separate cusps are still visible (e.g., in pharynx of fishes)2. Fusion of individual teeth during ontogeny: separate cusps may not still be visible (e.g., lungfishes, chimaeras)
9 Types of Mammalian Teeth and Dental Formulae Incisor teeth (I), typically these are replacedCanine teeth (C), typically these are replacedPremolar teeth (P), typically these are replacedMolar teeth (M), typically these are not replacedFormulae are expressed as type # in upper jaw/# in lower jawI 5/4, C 1/1, P 2/2, M 4/4 = opossumI 2/2, C 1/1, P 2/2, M 3/3 = humans
12 Terms for Mammalian Molars Tribosphenic molars - plesiomorphic condition seen in opossums and insectivoresBunodont molars - low-crowned condition seen in omnivores such as humans and pigsLophodont molars (e.g., Rhinoceros, Fig. 16-9A)Selenodont molars (e.g., deer, Fig. 16-9B).Molarization of premolars (remember that premolars are replaced wheras molars are not replaced.)High-crowned, or hypsodont, molars (e.g., horse, Fig C).