Horse teeth age will have between 36 and 44 teeth. All equines are heterodontous, which means that they have different shaped teeth for different purposes. All horses have twelve incisors at the front of the mouth, used primarily for cutting food, most often grass, whilst grazing. They are also used as part of a horse's attack or defence against predators, or as part of establishing social hierarchy within the herd. Immediately behind the front incisors is the interdental space, where no teeth grow from the gums. This is where the bit is placed, if used, when horses are ridden. Behind the interdental
Hinge teeth sides). This arrangement is characteristic of the venus clams (Veneridae), the cockles (Cardiidae) and several other important groups. In the "desmodont" hinge, also known as an "asthenodont" hinge, the hinge consists of a large ligamentous resilifer (or chondrophore) which replaces the cardinal teeth, as in the soft-shell clams (Myidae). The "anodont" hinge is characterized by a strong ligament (or a series of transverse ligamental grooves as in the "Isognomonidae"), however, true teeth are absent in adults as is the case in the pen shells (Pinnidae), tree oysters (Isognomonidae), the pearl oysters (Pteriidae), and some freshwater mussels such as the genus