Sperm Whales
The largest toothed predator with huge head, compared to its tiny eyes, looked kind of cute.
The salt spray kissed my face as I adjusted my camera, the pre-dawn light painting the ocean in hues of grey and lavender. Our small boat pitched gently on the waves. Captain Samuel sat beside, holding his hydrophone, its earpiece nestled against his ears, listening to the whispers of the deep. The air hummed with the promise of discovery, a tangible excitement vibrating through me. Captain Samuel had a knack for finding them; he claimed it was his sixth sense and his experiences, honed over years spent on the water, but I suspected his hydrophone played a crucial role. After a while, he straightened, a subtle grin spreading across his face. "There," he pointed towards a section of the seemingly placid ocean. “Many sperm whales, I found them." He adjusted the hydrophone’s volume, letting me hear the rhythmic, percussive clicks – a language only the ocean truly understands. My heart pounded.
Each unique click served as a guiding star in the vast marine expanse, igniting our sense of purpose and anticipation. Suddenly, a series of rhythmic, powerful blows broke the tranquility. A dark shape surfaced, momentarily outlined against the shimmering water. It was massive yet graceful as it pushed air from its lungs, creating a mist onto the air before dissipating in the gentle breeze. Each breath was a reminder of its sheer size and strength of this creature. The sound of each exhale was deep and resonant, echoing across the ocean. Right in front of my eyes, that was my first encounter to the largest toothed whale.
Sperm whale, also known as the cachalot (Physeter macrocephalus), can dive to impressive depths of up to 3,280 feet, for as long as 90 minutes, as they hunt for giant squid, their primary food source. Moreover, they possess the largest brain of any creature believed to have lived on Earth, a fact that underscores their unique biological characteristics. These majestic creatures derive their name from a fascinating waxy substance known as spermaceti, which is found in significant quantities within their heads. Their enormous heads, that contain large reserves of spermaceti, has piqued the interest of both whalers and scientists alike.
In the past, whalers mistakenly thought the oily fluid was sperm, but to this day, scientists have not definitively uncovered the exact function of this mysterious substance. One prevalent theory suggests that spermaceti, which has the distinct property of hardening into wax at lower temperatures, may assist the whale in managing its buoyancy, allowing it to dive deep into the ocean and return to the surface effectively. In addition, it is believed that the spermaceti acts as an oil sac that aids the whales in focusing sound, which is crucial for their echolocation abilities. Historically, spermaceti was harvested and utilized in various applications, including oil lamps, lubricants, and candles. The sperm whale was a principal target of the commercial whaling industry from the year 1800 until the practice was largely ended in 1987, which led to a drastic decline in their populations. While whaling no longer poses a significant threat, it is important to note that sperm whale populations are still in the process of recovery. The fascinating and complex nature of sperm whales, particularly the contents of their heads filled with spermaceti, continues to intrigue scientists, who are determined to unlock the secrets of this enigmatic substance and its role in the lives of these magnificent marine mammals.
Large, sexually mature males that are in their late 20s or older will occasionally return to the tropical breeding areas to mate.
Before we entered the water, we took a moment to observe the gentle movements of the sperm whales and their behavior. Some were shy, retreating slightly at our presence, while others floated calmly at the surface, basking in the sun. Our eyes were drawn to a newborn swimming independently, its small body cutting through the water with a sense of purpose as it awaited the return of the adults who had ventured into the depths to hunt. We made a conscious decision to leave it, allowing the small one remained in their most comfortable state while we marveled at their natural world.
I believed it was all the respects that we have given to the nature, in return, we were treated kindly with some of the most amazing whale encounters. One by one, we slided into the water quietly, making minimal splashes. Our entry was slow and deliberate, allowing the whales to approach us if they chose to. We stayed mindful of their space, moving gently and avoiding abrupt movements that could startle them. The rhythm of our strokes matched the tranquil ebb and flow of the water, creating a harmonious experience. We oriented ourselves, keeping an eye on the whales, watching as they got closer, I could hear their powerful breaths and we shared eye contact. When I were looking at them, they were studying us too.
Every interaction was a reminder of the importance of preserving their natural habitat and treating them with the care they deserve. The BIG Male! - the Bull could basically be differentiated by his size, his head, a lot bigger with lots of scars, and his skin is white. Scientists have long believed that male sperm whales are among nature’s loneliest creatures. Unlike the female, similar to female elephants, who spend their entire lives living in structured matrilineal societies among their kins, the males experience independence or isolation as soon as they have grown mature. After this point, they spend the majority of their lives alone in the expansive and often desolate open ocean.
Although, the young males frequently form groups with those who are about their same age, which, in turn, results in the creation of temporary social associations, as they mature, the males tend to break into smaller, more transient groups. Eventually, the larger, older males usually adopt a solitary existence, having established a lifestyle that favors loneliness. The bulls generally prefer to inhabit cooler, higher latitudes, while the females remain in warmer waters where food is more plentiful and readily available. Males are typically ready to breed at around 18 years old, but they do not reach their full size and physical maturity until they are about 50 years old. After this significant period of solitary living, they return to the female ranges specifically for the purpose of mating.
“Scars are a warrior’s beauty marks.” In sperm whales, it is well documented that some scars, often found arranged in parallel lines, are the result of intraspecific fighting among males. These distinctive scars might be widely perceived as indicators of male “quality” within their social hierarchy. Sperm whales primarily hunt cephalopods as their main source of prey, which means they do not rely on their teeth for capturing food. This unique evolutionary trait has allowed the whales to develop their teeth into formidable weapons for fighting. As a result, the significance of these scars in signaling quality and social standing increases, helping to mitigate the risks associated with escalating aggressive encounters between individuals that may be unevenly matched in size and strength. These characteristic scars tend to begin appearing around the time of sexual maturity in the whales. They serve as indicators of age, with older and larger individuals typically bearing more numerous scars. In fact, some of these whales possess so many scars that they can overlap each other, creating a complex tapestry of their life experiences. In contrast, circular scars can be attributed to battles with the sperm whales’ primary prey, the giant squid. These circular patterns are formed by the strong suckers that adorn the arms and tentacles of the squid, leaving distinct markings on the skin of the whales.
A playful sperm whale showing us his toy, the kelp. It was a lucky day.
One particularly intriguing behavior that we discovered involves a sperm whale engaging in playful antics with some kelp it found floating in ocean—moving the kelp delicately between its fins, rolling around joyfully with it, occasionally putting it into its mouth, and, most curiously, balancing it atop its head as if it were wearing a stylish hat. This fascinating behavior could be known as ‘kelping’ which has recently been described in new study as a “global phenomenon.” There is certainly no denying that kelping appears to be an enjoyable activity. However, could there be an underlying purpose to this playful display? Olaf Meynecke, a researcher at Griffith University and one of the co-authors of the study, posits that the manner in which these whales can gently and skillfully maneuver the kelp using various parts of their bodies may indicate a form of mobility training. Additionally, it may provide a pleasurable sensation for the whales and could be advantageous for their skin. Some researchers suggest that by rolling around and frolicking with clumps of kelp, these gentle giants might receive a natural scrub that aids in removing dead skin and parasites. It’s somewhat akin to an all-natural exfoliating session, which serves to rejuvenate and refresh their skin. A compelling reason for this behavior may be that the kelp acts similarly to a toothbrush, as the specific area of their mouths where they often have difficulty maintaining cleanliness is notably challenging to reach.
While a pod of sperm whale was socialising, a bull came to check on me.
“You don’t see this every day, enjoy my friend.” A big pod of sperm whale socialised with each others, they danced, they twirled, rubbing their head against each others, they played together, and they gossiped. Until they are seen in action, it is nearly impossible to fully imagine the remarkable fluid athleticism of these massive, torpedo-shaped beings, who move effortlessly through the water with astonishing flexibility, grace, and agility. Their socialization behavior can occur within singular social units but often includes one or more additional groups, showcasing the complexity of their interactions. Off the coast of Dominica, groupings of up to seventy sperm whales have been observed exhibiting this gregarious activity, which highlights their unique social structures. The whales purposefully come together to relax, cultivate friendships and family alliances, and enjoy one another’s company in a manner that is both fascinating and heartwarming. These gatherings can last for a few hours to several days, demonstrating the importance of social bonds in their lives.
During periods of socializing, the whales actively participate in a variety of enjoyable activities that foster a sense of affinity and work to strengthen their intricate social bonds. They communicate effusively with each other, and engage in numerous kinesthetic forms of interaction, frequently rubbing against or gently nuzzling one another in a display of affection. Juveniles and calves particularly relish rigorous bouts of playful activity that involve jostling, bubbling, twirling, intertwining their bodies, and jawing at each other with open mouths and a sense of mock ferocity. These captivating behaviors are performed with an elegance that resembles a beautifully choreographed dance.
These gatherings help strengthen social bonds within the group and provide important physical benefits. The playful activities allow young whales to exercise at the surface, which is crucial for building the muscles and stamina they need for diving and hunting as adults. Sperm whales shed skin daily as a natural way to keep their skin healthy and free from parasites. The physical interactions during socializing, like body rubbing, may speed up this skin shedding, promoting overall skin health in the pod.
Another interesting occurrence observed among these majestic creatures is the propensity for the whales to defecate en masse when they are engaged in socializing activities. Sperm whales, known for their constant feeding habits, eat continuously and, as a result, defecate regularly throughout the day. They often do so while swimming gracefully on the surface and right before making their descent into the depths of the ocean, releasing their bowels in clouds of liquified excrement that can act as a smokescreen to effectively camouflage their sudden departure from the scene. During moments of social interaction, these whales frequently display a tendency to defecate in unison, particularly when they find themselves in the midst of a playful romp with one another. Why they choose to behave in this particular manner during such settings, however, remains a mystery that has yet to be fully understood.
A potential benefit of socialization among mixed groups is that these engaging gatherings provide valuable training for young males as they prepare for their eventual departure from their family social units. In these social configurations, the young males are given a unique opportunity to practice their social autonomy and gradually develop a sense of independence from their primary family group, all while still remaining within a supportive and nurturing social environment. This gradual process may serve as a critical first step towards merging with other young males from different units, ultimately leading to the formation of bachelor groups as part of their broader maturation journey.
The existence of specialized spindle neurons in the brains of sperm whales serves as a vital impetus for intentional acts of social bonding among them. These unique cells, often referred to as ‘von Economo’ neurons, not only support the formation of enduring relationships but also enable the whales to engage with conscious specificity in various social situations. In other words, they are biologically wired to exercise a level of emotional discernment that influences their social interactions. Much like humans, whales tend to enjoy the company of certain individuals more than others, highlighting the complexity of their social structures and preferences.
Sperm whales exhibit distinct preferences for their favorite friends as they engage in their daily activities. They naturally gravitate towards their closest friends, frequently swimming in closer proximity and communicating more often with those favored companions. However, we observe that during specific periods of socialization, the whales expand their friendship circles considerably to include interactions with other members of their larger social units or even with individuals from different groups. This behavior suggests a complex social structure where relationships can shift and adapt based on social contexts and opportunities.
After socializing, they would go back to the group where they belonged. What was left in the ocean was oil, their skins and exhausted. We followed a group of whale, and they dived but not deep. By keeping a distance, I watched them forming vertically. Yes, they were getting ready to take a nap. Sperm whales do not typically sleep horizontally like most other whale species. In contrast, species of baleen whales, such as humpbacks and blues, usually adopt a sleeping position where they lie near the water’s surface, with their massive, streamlined bodies oriented parallel to the ocean's expansive surface. Sperm whales sleep in a distinct formation, with their heads clustered closely together while their tails point outward in opposite directions, creating a visually striking and harmonious arrangement that is captivating to observe. Many species of dolphins also exhibit similar horizontal sleeping postures, allowing them to rest effectively while remaining vigilant to their surroundings. However, sperm whales stand out as the only known cetaceans that regularly sleep in a manner that is distinctively perpendicular, adopting a unique vertical or head-up orientation that is quite different from their counterparts.
Sperm whales slept
vertically, feeling exhausted, after socialising.
Sperm whales initiate this unique vertical sleep by first angling themselves head-down and then descending to impressive depths that can reach several times their own body length. Following this initial positioning, they passively rotate into a head-up posture and gradually drift back toward the surface, all while their bodies remain largely buoyant. This fascinating research has demonstrated that sperm whales engage in a form of unihemispheric slow-wave sleep (USWS) while in this vertical position. USWS is a remarkable phenomenon in which one hemisphere of the brain shuts down to allow for sleep, while the other hemisphere remains alert and responsive to the surrounding environment, thus striking a balance between rest and awareness. This remarkable trait has also been observed in certain bird species and among dolphins, highlighting an intriguing aspect of marine biology. Scientists hypothesize that USWS allows sperm whales to maintain vigilance against potential threats, efficiently regulate their breathing, preserve essential social connections, and continue moving gracefully in the water while still obtaining restorative sleep necessary for their well-being. Moreover, the adaptation of USWS may also provide insightful clues into the long lifespans of sperm whales, enabling them to achieve quality rest routinely while minimizing exhaustion over time, even when they must remain mindful of various threats in their ever-changing environment.
Sperm whales must consciously regulate their buoyancy while sleeping beneath the surface of the ocean. By positioning themselves vertically with their blowholes directed upward, they simplify the process of maintaining neutral buoyancy through only minor adjustments in their body posture. In contrast, adopting horizontal postures would necessitate more strenuous swimming actions to actively prevent themselves from either rising to the surface or sinking deeper into the water. Thus, their vertical orientation effectively minimizes their energy expenditure related to buoyancy control.
This vertical posture allows sperm whales to maintain position with very little active effort, enabling them to hover comfortably at their preferred depth. Their specialized spermaceti organ plays a crucial role, as it can make subtle changes to counteract any passive drifting that may occur. By remaining relatively still in this position, they are able to conserve energy that would otherwise be spent on horizontal travel. Their metabolic rates may decrease significantly—by 50% or more—when compared to when they are awake, which further aids in reducing their overall caloric burn during these periods.
Additionally, group synchronization of sleep cycles allows these whales to take advantage of hydrodynamic drafting. This collaboration results in a reduction of drag and consequently lowers energy costs for the group. As voluntary breathers, sperm whales must make the conscious decision about when to surface in order to breathe. By sleeping in a vertical orientation, they gain easy access to oxygen, requiring minimal exertion as their blowholes are conveniently positioned right at the water's surface. This method is decidedly more efficient than having to fully awaken and swim from horizontal postures, which would demand much more effort and energy.
In a vertical position, the whales are also able to absorb more oxygen effectively since water pressure increases with depth, allowing them to maximize the intake of oxygen with each breath taken. Furthermore, passive breathing at the surface enhances the diffusion of oxygen into their bodies compared to taking breaths in deeper, oxygen-poor waters, making this strategy an advantageous adaptation for their survival.
By remaining in a vertical position and staying motionless, sperm whales effectively minimize their visibility to potential predators during those periods of vulnerability when they are most at risk. This unique posture not only facilitates the use of echolocation to continuously monitor for threats even while they are asleep but also allows the whales to react quickly if they detect any danger. Vertical orientation enables these magnificent creatures to surface swiftly when necessary, helping them execute rapid responses to avoid potential threats. Additionally, the close proximity within pods while sleeping in a vertical position is believed to aid in group threat detection, enhancing their overall safety.
Sleeping parallel along thermoclines—distinct zones of rapid temperature change within the water column—allows sperm whales to take advantage of cooler water during the summer months while enjoying warmer water in the winter. When they drift vertically, heat loss is significantly reduced due to less surface area exposure compared to more horizontal postures. This vertical shape allows them to retain more body heat in the core of their bodies rather than letting it disperse to the extremities. Moreover, the insulative blubber they possess works most efficiently when it is concentrated in a column during their vertical sleeping position. The spermaceti organ is likely involved in regulating blood flow to the skin surface, playing a crucial role in maintaining their body temperature effectively.
As the sun dipped below the horizon, painting the sky in vibrant hues of orange and purple, we steered the vessel back towards the shore. The tiredness remained, a gentle reminder of the physical demands of our work, but it was now overshadowed by the exhilarating feeling of accomplishment and the boundless potential of future discoveries. The encounter with the sperm whale had not only been a beautiful experience, filled with thrilling adventure, but it had also been the beginning of a potentially groundbreaking research project. The happiness was profound, a blend of shared success, exhaustion earned, and the promise of future expeditions. The end of our encounter marked not an end, but a truly magnificent beginning.
References
Meynecke, J. -O., & Kela, H. (2023). What’s at Play: Humpback Whale Interaction with Seaweed Is a Global Phenomenon. Journal of Marine Science and Engineering, 11(9), 1802. https://doi.org/10.3390/jmse11091802
Lettevall, E., Richter, C., Jaquet, N., Slooten, E., Dawson, S., Whitehead, H., Christal, J., & Howard, P. M. (2002). Social structure and residency in aggregations of male sperm whales. Canadian Journal of Zoology, 80(7), 1189–1196. https://doi.org/10.1139/z02-102
MacLeod, C. D. (1998). Intraspecific scarring in odontocete cetaceans: an indicator of male ‘quality’in aggressive social interactions?. Journal of Zoology, 244(1), 71-77.
Frank, D. (2023, October 19). Why Do Sperm Whales Sleep Vertically? (Explained). Ocean Action Hub. https://www.oceanactionhub.org/sperm-whales-sleep-vertically/
Mitrica, D. (2024, November 1). The Surprising Sleep of Sperm Whales: Vertical Naps in the Ocean Deep. ZME Science. https://www.zmescience.com/ecology/animals-ecology/sperm-whales-sleep-vertically/
Botelho De Oliveira, C. I., PhD. (2014). Behavioural ecology of the sperm whale (Physeter macrocephalus) in the North Atlantic Ocean. In J. M. Doutor Gonçalves, M. A. Doutora Silva, Centro do IMAR da Universidade dos Açores, & M. Wahlberg, Dissertação Apresentada À Universidade Dos Açores Para Obtenção Do Grau De Doutor No Ramo De Ciências Do Mar, Especialidade Em Ecologia Marinha[Thesis]. Universidade dos Açores. https://core.ac.uk/download/pdf/61445435.pdf
Magazine, H. (n.d.). The Bro Bonds of Sperm Whales | Hakai Magazine. Hakai Magazine. https://hakaimagazine.com/news/the-bro-bonds-of-sperm-whales/#:~:text=Unlike%20female%20sperm%20whales%2C%20which,majority%20of%20their%20lives%20alone.