Salmon possess teeth, but their dental structure is far from static. These complex fish undergo dramatic physical changes throughout their lives, and their dentition reflects this variability across different life stages. The presence and form of their teeth change significantly depending on whether the fish is actively feeding in the ocean or migrating upstream to reproduce. This adaptive biology allows them to be highly effective predators and fierce competitors in freshwater spawning grounds.
Anatomy and Function of Feeding Teeth
When salmon are actively feeding in the saltwater environment, their dentition consists of numerous small, sharp structures. These teeth are not designed for chewing or grinding food; their primary function is to grasp and secure slippery, fast-moving prey.
These small, pointed structures are typically conical and angled backward toward the throat. This backward orientation prevents struggling prey, such as fish or squid, from escaping once caught. Since prey is generally swallowed whole, the teeth function purely as a holding mechanism.
The teeth are not confined only to the main upper and lower jaws. Salmon possess teeth in multiple locations throughout the mouth cavity, a characteristic of many predatory fish. These include lingual teeth on the tongue and teeth on the roof of the mouth.
The roof of the mouth features two sets of teeth: vomerine teeth, which anchor to the vomer bone, and palatine teeth, which anchor to the palatine bones. This widespread arrangement creates a highly effective, rough surface that ensures anything caught is held firmly and directed toward the esophagus.
The appearance of these feeding teeth can vary between species, though their general function remains consistent. For example, Chinook salmon have large, prominent teeth even in the marine phase compared to other species. The feeding dentition is optimized for an opportunistic, carnivorous diet in the open ocean.
Teeth Transformation During Spawning
The dentition of salmon undergoes a remarkable transformation as they cease feeding and begin their migration to freshwater spawning grounds. This change is most pronounced in males. The jaw teeth, which were once small and needle-like, become significantly enlarged, taking on a canine-like appearance.
The most visible change is the development of the “kype,” a pronounced, hook-like structure that forms at the tip of the lower jaw. This bony hook grows rapidly and fits into a corresponding depression in the upper jaw. The kype’s development is synchronized with the enlargement of the jaw teeth, creating a powerful, altered mouth structure.
This robust dentition is not used for eating, as migrating salmon rely entirely on stored fat reserves and stop consuming food. Instead, the enlarged teeth and the kype function as secondary sexual characteristics. They are used primarily for displaying dominance among rival males and fighting to secure access to spawning females and territory.
While the jaw teeth enlarge, the teeth located on the roof of the mouth and tongue often become less prominent. Some non-jaw teeth may be reabsorbed or become covered by oral mucosa as the fish transitions to its non-feeding state. This dental alteration is a specialized adaptation for reproductive competition.
How Tooth Structure Relates to Salmon Diet
The small, sharp, and conical structure of the feeding teeth is linked to the salmon’s ecological niche as a pelagic predator. These teeth are adapted for a diet consisting of highly motile and slippery organisms like small fish, squid, and crustaceans. This diet requires a quick and secure grip to prevent escape.
The inward-curving design and multiple locations of the teeth ensure that once prey is snatched, it cannot easily back out of the mouth. The lack of broad, flat teeth confirms that the salmon’s diet does not involve extensive crushing or grinding of plant matter or hard-shelled organisms.
The degree of dentition reflects differences in feeding preferences among various species. Chinook salmon, which consume larger fish like herring, possess prominent teeth well-suited for subduing this kind of prey. In contrast, Pink salmon, whose diet includes a greater proportion of smaller invertebrates, have fewer and smaller teeth.
This variation shows that while all salmon are carnivorous, the size and prominence of their teeth mirror the size and type of prey they target. The simple, sharp, and numerous teeth of the ocean-going salmon are a highly effective design for an active hunter in the marine food web.