The size of a whale often leads to questions about what these massive marine mammals consume. Many assume whales must eat large prey like sharks or fish, but the reality is much more complex and varied. Curiosity often centers on whether whales eat shrimp, a confusion stemming from the true nature of their primary food source. Understanding the diet of any whale requires focusing on the specialized anatomical tools they use for foraging. Whales employ two completely different approaches to hunting in the ocean.
The Two Main Types of Whale Diets
The entire order of whales, dolphins, and porpoises is divided into two distinct suborders, which dictates their feeding habits based on mouth anatomy. One group is the Mysticetes, or “moustached whales,” including the blue, humpback, and right whales. They lack teeth in adulthood, instead using specialized structures called baleen plates. The second group is the Odontocetes, or toothed whales, encompassing sperm whales, orcas, dolphins, and porpoises. These animals possess conical teeth designed for grasping rather than chewing. This divergence occurred over 34 million years ago, setting the stage for two different feeding ecologies. Baleen plates are made of keratin and hang in rows from the upper jaw.
The Truth About Krill and Filter Feeding
The confusion about whales eating shrimp relates to the main food source of filter-feeding Mysticetes. These large whales primarily consume krill, which are small, shrimp-like crustaceans that swim in massive swarms. Krill are a type of zooplankton and not true shrimp, which are generally not a major food item for most large whales. However, the Northern Indian Ocean blue whale subspecies has been documented to feed predominantly on sergestid shrimp when available.
Most baleen whales rely on the abundance of krill, copepods, and small schooling fish, employing various filter-feeding methods to harvest these tiny organisms in bulk. Rorquals, including blue and fin whales, use lunge feeding, accelerating rapidly to engulf a huge volume of water and prey. A blue whale can consume up to four tons of krill per day during peak feeding season.
After engulfing the water, the whale contracts its throat pleats and uses its tongue to force the water out through the baleen plates. The dense fringes on the keratin plates act as a sieve, trapping the tiny organisms inside the mouth. Other species, like the right whale, use skim feeding, swimming slowly through the water with their mouths open. Gray whales use silt sifting, sucking up sediment from the seafloor and straining out bottom-dwelling crustaceans like amphipods.
What Toothed Whales Hunt
The Odontocetes, or toothed whales, function as active pursuit predators that hunt individual, larger prey items. Their diet is varied and includes fish, squid, and other marine mammals. These whales use a highly sophisticated biological sonar known as echolocation to navigate and locate prey, especially in deep or murky waters. They emit a series of clicks and then interpret the returning echoes to pinpoint the target’s location, size, and shape.
The sperm whale, the largest of the toothed whales, dives to extreme depths to hunt giant squid and other cephalopods, which make up the vast majority of its diet. They do not typically use their teeth for chewing but rather for grasping, often swallowing their prey whole. Orcas, the largest members of the oceanic dolphin family, are apex predators with highly specialized and varied diets.
Different groups of orcas focus on schooling fish like salmon, while others exclusively hunt marine mammals such as seals, sea lions, and even other whale species. Toothed whales often display complex social hunting behaviors, such as corralling schools of fish into dense “bait balls” before taking turns to feed. These coordinated efforts demonstrate the strategic nature of their predation, highlighting their adaptability to different marine environments.