Sperm Whale Echolocation: Master Navigators of the Deep
Cover Image Credit: SDM Diving
Introduction to Sperm Whales
Sperm whales (Physeter macrocephalus) are the largest member of the toothed whale family and are widespread throughout the world’s oceans. Unlike humpback and some other baleen whale species, sperm whales largely do not follow long annual migrations to winter breeding grounds. Instead, they travel as needed—wherever food is available—and feed daily.
Sexual Dimorphism and Distribution
Sperm whales are sexually dimorphic. Once males reach sexual maturity, they separate by latitude. Females and young males generally inhabit higher latitudes. Mature males (bulls), however, become solitary and move south to live in lower latitudes. Periodically, they return to higher latitudes to breed and socialise.
Echolocation Biology
The sperm whale has a uniquely shaped body, featuring a large, block-shaped head. This accounts for about one-quarter to one-third of its total body length. The shape evolved to support deep-sea hunting and communication during long dives.
The species gets its name from the spermaceti organ, which contains a waxy, oily substance resembling sperm. This organ plays a central role in sound production and echolocation. It can hold up to 1900 litres of spermaceti oil. The speed of sound in spermaceti is about 2,684 metres per second—almost twice as fast as in the melon of dolphins.
The Spermaceti Organ and Junk
Beneath the spermaceti organ lies the “junk” or melon. It consists of spermaceti-filled compartments separated by connective tissue and cartilage. Two air passages run through the head. The left leads to the blowhole. The right runs beneath the spermaceti organ, through the phonic lips, and into the distal sac at the nose’s front. This sac connects both to the blowhole and the left air passage.
Acoustic Lens and Click Production
Clicks are produced when the whale closes its blowhole and forces air through the phonic lips. The sound travels backward through the spermaceti organ. It reflects off the frontal sac at the skull’s front and redirects into the melon. The melon acts as an acoustic lens, focusing the outgoing click. Some sound energy reflects forward again, undergoing additional reflections.
Multi-Pulse Clicks and Echo Reception
These quick reflections create the multi-pulse click structure typical of sperm whales. The frontal sac, with knobs and grooves, reflects sound. Grooves trap a thin film of air, stable at any depth or orientation. This creates a highly effective sound mirror.
Echoes return through the lower jaw. A fat-filled canal transmits them to the inner ear, completing the echolocation system.
Vocalisations and Frequency
Sperm whales use a specific type of echolocation click for prey searching. These fall within the 10 Hz to 30 kHz range. Clicks can reach 236 dB—the loudest of any animal. They are detectable over 15 kilometres.
During hunting, whales emit long sequences of regular clicks. These occur at intervals of 0.5 to 2 seconds. Rapid click trains, called “creaks,” are heard during the final prey pursuit phase.
Sound Types and Usage
Madsen et al. describe usual clicks as suited for long-range echolocation. Creak clicks are similar to echolocating bat buzzes. Usual clicks help locate prey up to 16 km away. Creak clicks work best at shorter ranges, around 6 km.
Calves and Passive Listening
Tonnerson et al. tagged three sperm whale calves and recorded 15 hours of data. Calves rarely used codas—social clicks from adults. Instead, they likely listened for acoustic cues from nearby whales.
Early Foraging Behaviour
Calves showed good diving skills. One dove to 662 metres for 44 minutes. It produced echolocation buzzes, possibly testing independent foraging. These findings suggest calves may begin eating prey earlier than once believed.
Odontocetes and Click Intervals
Among toothed whales, a link exists between body size and inter-click interval (ICI). Larger whales use longer ICIs. This gives time for echoes to return from distant prey. It helps them scan wide areas and meet high energy demands.
Foraging Patterns
Sperm whales spend over 70% of their time foraging alone. Most dives range between 300 and 800 metres. Some go beyond 1000 metres. These long dives take place along the continental shelf.
They feed on squid, octopus, rays, and sharks. However, medium-sized squid make up most of their diet. A single whale may eat up to 1000 kg of food daily.
Acoustic Reflection Studies
Tonnerson et al. tagged three whales’ noses to track sound reflections. One whale showed over 6000 acoustic reflections. This suggests long-range echolocation is used to scan for prey.
One male kept high inter-click intervals. This allowed a wide acoustic field. It supported continuous monitoring of the environment.
Timing and Purpose of Buzzes
Previously, it was believed sperm whales could stun prey with sound. However, Tonnerson’s study disproved this. Buzzes were initiated more than 20 metres from prey.
Instead, whales reduce signal strength for better tracking accuracy. Compared to beaked whales that buzz at one body length away, sperm whales buzz at four body lengths. This reflects their need for earlier updates due to slower turning.
Navigating the Environment
Besides prey detection, sperm whales use echolocation to navigate. Echoes from the seafloor help them map prey-rich regions. This advantage aids in finding feeding grounds compared to other deep divers with shorter sonar ranges.
Sperm Whales in Bremer Bay
During Killer Whale Expeditions in Bremer Bay, sperm whales are frequently sighted. Calm, flat days are ideal. Crew observe solitary whales logging at the surface and maternal pods reuniting through tail slaps and breaches. Each encounter feels profound.
Bremer Bay and the Sub Basin
In 2024, a pod of sperm whales was chased into shallow waters by orcas. This forced them onto the continental shelf. The event stunned crew and passengers alike. Nothing of that scale had been seen before.
Other Notable Encounters
Orcas have previously harassed sperm whales. Usually, they try to steal prey. But this time, the encounter lasted over 20 minutes. The whales responded by forming a “rosette.”
The Rosette Formation
Whales form a circle with tails outward, calves in the centre. Adults also performed “defence defecation,” releasing faeces and stirring it with their tails. This discouraged further orca action. Some orcas did get a piece of meat, but it is unclear if it came from the whales. Regardless, it was an incredible sight.
Join a Naturaliste Charters Expedition
Want to see these deep-sea giants in the wild? Join Naturaliste Charters in Bremer Bay. December to April is the best time to observe them. You will not regret this once-in-a-lifetime encounter.
