Bottlenose dolphins are marine mammals found in coastal and offshore waters globally. Understanding their diet provides insight into their ecological interactions and behaviors.
Diverse Diet of Bottlenose Dolphins
Bottlenose dolphins are opportunistic predators; their diet is varied and depends on availability. Their primary food sources include a wide array of fish species, along with cephalopods such as squid and octopus. Crustaceans like shrimp and crabs also form part of their diet.
The availability of prey is influenced by geographical location, with coastal dolphins often consuming fish and bottom-dwelling invertebrates, while offshore dolphins tend to eat fish and squid. Seasonal changes also affect their diet; for example, bottlenose dolphins in Scotland favor salmon when abundant in spring and summer, shifting to herring and mackerel in winter. Adult bottlenose dolphins typically consume about 4% to 6% of their body weight in food daily, which can be around 13 to 30 pounds.
Common Prey Species
Commonly targeted fish species include mullet, croakers, mackerel, herring, sardines, and catfish in some regions. Beyond fish, their diet includes various species of squid and small octopuses. They also consume crustaceans like shrimp and crabs; studies have shown crabs can account for a significant portion of the diet in some coastal bottlenose dolphin populations, sometimes up to 25%.
Hunting Techniques and Adaptations
Bottlenose dolphins employ sophisticated hunting techniques, often showcasing their intelligence and cooperative abilities. They use individual pursuit for fast-moving fish and engage in cooperative hunting, where groups herd fish into tight “bait balls” before taking turns to feed. One method involves “tail-slapping” or “fish-whacking,” where dolphins use their powerful flukes to stun or disorient fish, sometimes sending them flying out of the water, making them easier to catch.
Another cooperative technique is “mud-ring feeding,” observed in shallow waters. Dolphins create a circular wall of mud by stirring up the seabed with their tails, trapping fish inside. The disoriented fish may leap out of the water, where waiting dolphins can catch them.
“Strand feeding” is a learned behavior where dolphins cooperatively drive fish onto a mudflat or shoreline, briefly beaching themselves to snatch the stranded prey before sliding back into the water. This risky behavior is often passed down from mothers to calves.
Echolocation plays a role in their hunting, allowing them to locate and identify prey even in murky waters or at night by emitting high-frequency clicks and interpreting the returning echoes. Their physical adaptations, such as cone-shaped teeth, are designed for grasping rather than chewing, as they swallow their prey whole. Flexible bodies and powerful tails also aid in maneuvering and stunning prey during hunts.
When consuming challenging prey like octopuses, dolphins have been observed “tenderizing” them by shaking, tossing, or slamming them against the water to incapacitate them and tear them into pieces. This prevents the octopus from clinging to their throat and causing suffocation.