A Dolphin’s Mouth: More Than Just a Smile

The iconic image of a dolphin often includes what appears to be a gentle, built-in smile. This feature contributes to their popularity and perception as perpetually happy creatures. This perception, however, simplifies a complex piece of anatomy. A dolphin’s mouth is not for expression but is a specialized structure for survival, and the shape we interpret as a smile is an anatomical coincidence.

Anatomy of the Dolphin’s Mouth

A dolphin’s mouth is part of its elongated jaws, known as a rostrum or beak. This structure is hydrodynamic, allowing the dolphin to move swiftly through the water with minimal resistance. For instance, bottlenose dolphins possess between 80 and 100 teeth.

All of a dolphin’s teeth are conical and uniform, a condition known as homodont dentition. Unlike human teeth, which are varied for different tasks, a dolphin’s teeth have a singular function: grasping. They are not used for chewing and interlock to provide a firm grip. Dolphins only get one set of teeth for their entire lives.

The tongue inside the mouth is muscular and agile. It plays a significant part in the feeding process, which follows the initial capture of prey. The entire oral structure is an adaptation for life as an aquatic hunter.

How Dolphins Use Their Mouths for Feeding

The primary use of a dolphin’s mouth is to capture and consume food. Dolphins catch fish, squid, and crustaceans. The conical teeth are perfectly shaped to hold onto slippery prey, preventing escape. Instead of chewing, they manipulate their catch with their tongue and swallow it whole.

To make swallowing easier, dolphins will often orient a fish to go down their throat head-first. This prevents the fish’s fins and scales from snagging in the throat. If prey is too large to be swallowed in one piece, a dolphin might thrash it against the water’s surface to break it into smaller chunks.

Dolphins have developed hunting strategies that involve their mouths and bodies. Some chase schools of fish toward mud banks, trapping them on shore before grabbing them. Others use a technique called “fish-kicking,” where they use their powerful tails to stun a fish before scooping it up.

The Truth About the Dolphin “Smile”

The “smile” of a dolphin is a fixed feature of its anatomy, not an expression of emotion. The upward curve of the jawline creates this illusion, as dolphins cannot move their facial muscles to form expressions in the way humans do. A dolphin will appear to be smiling whether it is healthy, sick, or injured.

This misinterpretation is an example of anthropomorphism, the tendency to attribute human traits and emotions to animals. While it makes dolphins seem friendly, it can be misleading. Understanding that the smile is a structural characteristic helps in appreciating the animal for its natural behaviors.

Recent studies have observed that dolphins use an open-mouth gesture during social play, which might be a form of communication or bonding. However, this is distinct from the permanent, passive smile created by their bone structure.