The sperm whale, a deep-sea predator, navigates the crushing pressures and darkness of the deep ocean to find its sustenance. Their diet primarily consists of large, deep-dwelling marine animals.
Primary Prey: Deep-Sea Delicacies
Sperm whales’ diet largely centers on deep-sea cephalopods. Squid, particularly large species such as the colossal and giant squid, form the primary part of their diet. These massive cephalopods can weigh up to a ton and measure over 12 meters, providing substantial nourishment. Evidence of their encounters with giant squid often appears as circular scars on the whales’ heads, left by squid suckers during struggles.
Beyond squid, sperm whales also consume a variety of deep-sea fish. Their diet can include demersal rays, various sharks like megamouth, sleeper, and mako sharks, and other fish such as cod, rockfish, and ling. Octopuses are another occasional component of their meals. These prey animals inhabit the same deep ocean zones and have soft bodies, generally easy for the whales to consume whole. Sperm whales must consume a substantial amount of food, typically 3 to 3.5 percent of their body weight daily, which can amount to nearly one ton for an adult.
Hunting in the Abyss
Sperm whales hunt in the dark, high-pressure deep sea. They primarily rely on echolocation, emitting powerful clicks to navigate and locate prey. These clicks are among the loudest sounds produced by any animal on Earth, and are thought to help stun or disorient their prey, making capture easier.
The whales are deep divers, routinely descending to depths of 400 to 1,000 meters for 35 to 45 minutes to forage. They can reach greater depths, with recorded dives exceeding 2,000 meters and lasting up to 120 minutes. Their jaw structure, featuring a narrow lower jaw with 18 to 26 conical teeth on each side, is adapted for grasping rather than chewing. In fact, the teeth are not essential for feeding, as sperm whales with missing or deformed teeth can still thrive. Instead, they primarily use suction feeding, drawing their prey into their mouths whole, a technique facilitated by their elastic throats.
Life in the Deep: Feeding Adaptations
Sperm whales possess adaptations that enable them to thrive in the challenging deep-sea environment. A prominent feature is the spermaceti organ, a large, oil-filled structure in their head. This organ generates and focuses the powerful sound waves for echolocation. The spermaceti organ is also thought to play a role in buoyancy control, with changes in the oil’s temperature and density potentially assisting the whale in descending and ascending.
Their large size and robust bodies are further adaptations for deep diving. A substantial body size allows for greater oxygen storage in their muscles and blood, through high concentrations of myoglobin and hemoglobin. To manage the extreme pressure, their ribcage is flexible, allowing their lungs to safely collapse during deep dives. Additionally, sperm whales exhibit physiological responses such as peripheral vasoconstriction, which redirects oxygenated blood to essential organs like the brain and heart, and bradycardia, a slowed heart rate, all of which conserve oxygen during prolonged underwater excursions.