Dolphins possess a distinctive dental structure, unlike the teeth of most land mammals. Unlike humans, who have different types of teeth for cutting, tearing, and grinding, a dolphin’s mouth is equipped with a uniform set of teeth. Understanding this specialized dentition offers insight into the unique lifestyle and feeding ecology of these ocean inhabitants.
The Specific Count and Structure
A typical common bottlenose dolphin possesses between 72 and 116 teeth, distributed evenly across both the upper and lower jaws. The form of these teeth is described as homodont, meaning all teeth are the same shape, which is conical or peg-like. This structure contrasts with the heterodont dentition of humans, which includes incisors, canines, premolars, and molars. Furthermore, dolphins are generally monophyodont, meaning they develop only a single set of permanent teeth that must last their entire lifespan. These teeth begin to erupt within the first few weeks or months of a calf’s life and are never replaced.
Variability Among Dolphin Species
While the common bottlenose dolphin provides a useful average, the number of teeth varies dramatically across the more than 40 species of oceanic dolphins. The Long-beaked common dolphin can have one of the highest counts, with some individuals possessing up to 268 teeth. Spinner dolphins often have between 180 and 260 fine, pointed teeth. On the opposite end of the spectrum is the Risso’s dolphin, which has one of the lowest tooth counts among all cetaceans. This species typically has between four and fourteen teeth, found only in the lower jaw. This specialized dentition reflects their diet, consisting almost entirely of squid and cuttlefish, which they capture primarily through suction.
Function and Feeding Behavior
A dolphin’s teeth are not designed for chewing or grinding food, but rather for effectively capturing and securing slippery aquatic prey. The interlocking, conical pegs function like a natural snare, ensuring that fast-moving fish or cephalopods cannot escape once grasped. Dolphins always swallow their food whole, often consuming fish head-first to prevent scales and fins from catching in their throat. This behavior explains why they do not require flat, crushing molars like many terrestrial mammals. Beyond feeding, the teeth also play a role in social interactions within a pod, where dolphins may “rake” their teeth across the skin of a subordinate individual to display dominance.
Teeth as Biological Markers
Dolphin teeth have a unique biological function unrelated to feeding: they serve as a record of the animal’s life history. Like tree trunks, dolphin teeth deposit annual layers of material called Growth Layer Groups (GLGs). These GLGs are composed of dentin and cementum, which are laid down in alternating opaque and translucent bands. Scientists can extract a tooth from a deceased dolphin, cut a thin slice, and examine it under a microscope to count these layers. Each counted GLG is accepted to represent one year of life, providing a reliable method for accurately estimating the dolphin’s age. This process offers researchers a powerful tool for understanding population demographics and life expectancy.