Durophagy
Durophagy is the eating behavior of animals that consume hard-shelled or exoskeleton-bearing organisms, such as corals, shelled mollusks, or crabs.
[7] Many Teleosts, for example the Atlantic wolffish, exhibit durophagous behaviour and crush hard prey with their appropriately adapted jaws and teeth.
[8][9] As in the Carnivora however, some largely herbivorous or omnivorous Teleost fishes too, exhibit durophagous behaviour in feeding on plant foods, in that they crack the hard stones of fruit that fall into their water: spectacular examples include relatives of the carnivorous piranhas — such species include Piaractus brachypomus and Piaractus mesopotamicus.
These bones have flat-crowned teeth and along with their dorsal fellows drawn by powerful muscles, create a crushing mill.
A series of biting movements completes the process and the shell fragments are spat out and the soft body is swallowed.
[10][11] Within the chondrichthyans, horn sharks (Heterodontidae), some rays (Myliobatidae) and chimeras (Holocephali) exhibit durophagous behaviour.
Sharks that crush prey have teeth with small, low rounded cusps that are numerous per row, or are molariform.
[8] The bonnethead shark Sphyrna tiburo uses ram feeding to capture crab, shrimp and fish which are placed between the molariform teeth where they are crushed.
By combining durophagous characteristics with altered kinematic and motor patterns, bonnethead sharks can prey on hard shelled animals.
The fusion of the palatoquadrate and mandibular symphysis, a restricted gape and asynchronous activation of the jaw adductors are key elements in the 'nutcracker' model of jaw-crushing ability.
[12][8] In eagle (Aetobatus narinari) and cow-nose (Rhinoptera javanica) rays, teeth are hexagonal and are arranged in anteroposterior files packed closely together in an alternating array to form an almost gap-free pavement, similar to the organization found in Chimeras.
Cow nose rays are specialized suction feeders, which open and close their jaws to generate water movements that are used to excavate buried prey.
The central hexagonal plate is very wide, taking up about half the width of the occlusal surface and it is flanked by three lateral files of smaller teeth on each side, the outermost being pentagonal.
[12] Shorebirds commonly consume bivalves and snails which are low in chitin but the calcium carbonate shell makes up a large portion of their weight.
Once prey is caught, the otters use their powerful jaws and sharp teeth to consume their meal quickly, even protective crustacean shells.
For larger, heavier-shelled prey, otters will sometimes exhibit tool-use behavior, breaking open sea urchins and mussels with a false stone used as an anvil.
[14][15] All mangabeys appear to be durophagous and possess relatively thick molar enamel and expanded premolars, dental adaptations for processing hard foods.
[16] The giant panda is mainly a herbivore despite its short, relatively unspecialized digestive tract that is characteristic of carnivores.
Giant pandas lack microbial digestion in their rumen or caecum that is typical of most herbivores for breaking down cellulose and lignin in plant cell walls.
They also reduce their energy expenditures by resting and only remaining active to feed, and they don't have a hibernation period, allowing them to have more foraging time.
The wolverine is an effective scavenger, capable of cracking heavy bones and shows the same adaptations in the jaw as the hyenas do.
