Dolphins are marine mammals belonging to the order Cetacea and the suborder Odontocetes (toothed whales). All dolphins are carnivores that actively hunt their food. Their streamlined bodies and complex social structures are adaptations that support a life spent pursuing and capturing prey in diverse aquatic environments. Their feeding habits reveal a diet and set of hunting behaviors that demonstrate flexibility and sophistication.
Primary Components of the Dolphin Diet
The vast majority of a dolphin’s nutritional intake is composed of small, schooling fish, cephalopods, and, less frequently, crustaceans. Fish form the foundational element of the diet for most dolphin species, providing the high-energy fuel necessary for their active, warm-blooded existence. Common fish prey includes species such as herring, cod, mackerel, mullet, and anchovies, which dolphins often target because their schooling behavior makes them efficient to hunt.
Cephalopods, primarily squid and octopus, represent another significant food source, especially for dolphin populations that forage in deeper, offshore waters. These prey items offer high protein and fat content. While less common, crustaceans like shrimp and crabs are occasionally consumed, typically by coastal or riverine dolphin species where they are more readily available. Dolphins do not chew their food; their cone-shaped teeth are designed for grasping, meaning they must swallow prey whole, usually head first.
Specialized Feeding Strategies
Dolphins employ sophisticated techniques to locate and capture prey, moving far beyond simple chase and capture. Echolocation is a fundamental tool, allowing dolphins to emit a series of high-frequency clicks that bounce off objects in the water. By interpreting the returning echoes, they can mentally map their surroundings and accurately determine the size, distance, and movement of potential prey, even in dark or murky conditions.
Cooperative hunting is a hallmark of dolphin behavior, where a pod works in coordination to maximize feeding efficiency. One common method involves herding a school of fish into a dense cluster, often called a “bait ball,” allowing individual dolphins to take turns swimming through the concentrated mass to feed. Some coastal populations, particularly bottlenose dolphins, use “mud-ring feeding” in shallow water. A dolphin swims in a tight circle, rapidly moving its tail along the seabed to create a curtain of disturbed mud and sediment. This temporary mud wall disorients and traps the fish, sometimes causing them to leap out of the water where the dolphins wait to catch them.
A different, culturally transmitted strategy is “sponging,” primarily observed in a specific population of female bottlenose dolphins in Shark Bay, Western Australia. These dolphins carry marine sponges on their rostrums, or beaks, while foraging on the seafloor. The sponge acts as a protective tool, shielding their sensitive skin from abrasive debris or stinging organisms while they search for prey hidden in the sediment. “Strand feeding” is another localized technique where dolphins intentionally chase fish onto a mudflat or beach, temporarily stranding themselves to quickly grab the prey before sliding back into the water.
Dietary Variation Across Species and Habitats
A dolphin’s specific diet is heavily influenced by its species and the environment it inhabits, leading to distinct feeding ecologies. Coastal dolphins, such as common bottlenose dolphins, are dietary generalists, consuming a wide variety of local, abundant fish, squid, and crustaceans found over the continental shelf. For example, studies of coastal bottlenose dolphins in North Carolina show a diet dominated by sciaenid fishes like Atlantic croaker in estuaries, while those near the ocean primarily consume weakfish and squid.
In contrast, oceanic dolphins, which live in the deep, open sea, often specialize in high-energy prey, such as deep-sea squid and pelagic fish that are adapted to offshore environments. Risso’s dolphins, for instance, are known to primarily forage on cephalopods in deeper waters, demonstrating a more specialized diet compared to their coastal relatives. The largest member of the dolphin family, the Orca (Killer Whale), exhibits the most extreme dietary variation, with populations forming specialized ecotypes.
Resident orca populations often focus almost entirely on fish, particularly salmon, displaying a highly specific, culturally learned preference. Transient orcas, however, are mammal-eaters, preying on seals, sea lions, and even other whales, which requires different hunting strategies and social coordination. River dolphins, like the Amazon river dolphin, have adapted to freshwater environments and consume a distinct menu of small, often bottom-dwelling, freshwater fish and crustaceans.
Daily Nutritional Requirements
The high-activity lifestyle and warm-blooded nature of dolphins necessitate a substantial daily food intake to maintain their metabolism, often consuming 4% to 8% of their total body weight each day. For a medium-sized dolphin weighing a few hundred pounds, this can translate to a consumption of 20 to 30 pounds of fish and squid daily.
The percentage of food consumed relative to body weight decreases as the dolphin grows larger and reaches maturity. Younger, smaller dolphins, which have a proportionally higher metabolic rate, may consume up to 12% of their body weight daily. Dolphins do not drink seawater to hydrate; instead, they acquire all necessary fluid through the food they eat. This process, known as obtaining metabolic water, extracts the water content directly from the tissues of the fish and squid they consume.