Dolphins are intelligent marine predators found in oceans, coastal waters, and some freshwater systems. They actively hunt a variety of marine life, playing a significant role in their ecosystems.
Main Prey Categories
Dolphins consume a wide array of animals, primarily fish, cephalopods, and occasionally crustaceans. Fish are the main part of most dolphin diets, with types varying by species and habitat. Common fish include herring, mackerel, mullet, sardines, anchovies, and cod. Some coastal dolphins also consume bottom-dwelling fish like saltwater catfish.
Cephalopods, such as squid and octopus, are another food source, especially for dolphins in deeper ocean waters. Risso’s dolphins, for instance, prefer deep-sea squids. Dolphins may use tactics, like slamming an octopus against the water’s surface, to dismember it.
Crustaceans, including shrimp and crabs, are also part of a dolphin’s diet, particularly in coastal or freshwater environments. River dolphins frequently include crustaceans and small river fish. Dolphins are opportunistic feeders, consuming whatever prey is most readily available.
Hunting Techniques
Dolphins employ sophisticated hunting techniques to capture prey. Echolocation is a biological sonar system where dolphins emit high-frequency clicks. By interpreting echoes, dolphins determine prey size, shape, distance, and internal structure, even in murky or dark waters.
Many dolphin species, particularly bottlenose dolphins, engage in cooperative hunting. Pods herd fish into a “bait ball,” then take turns feeding. Other cooperative methods include “mud-ringing” (creating a mud cloud to trap fish) and “strand feeding” (driving fish onto shore).
Individual hunting techniques are also used. Some dolphins use “fish-whacking” or “fish-kicking,” using tail flukes to stun or disorient fish. Dolphins do not chew food; they grab prey with their teeth and swallow it whole.
Factors Influencing Diet
A dolphin’s diet is influenced by its species, geographic location, seasonal prey availability, and individual age or size. Each of the over 40 dolphin species has specific dietary preferences based on habitat. Oceanic dolphins, for example, primarily consume fish and squid, while river dolphins often eat crustaceans and small river fish.
Geographic location impacts prey types; dolphins in colder waters may consume more fatty fish, while those in warmer regions might target smaller, faster-moving prey. Seasonal changes also lead dolphins to adapt diets, such as bottlenose dolphins in Scotland switching from salmon to herring and mackerel seasonally. Age and size also affect food intake, with younger dolphins having different nutritional needs.