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Tuesday September 27th, 2022

Lanka’s cultural sperm whale

Lankan waters harbour four especially charismatic whales and dolphins: sperm whale, blue whale, orca and bottlenose dolphin. Scientists now know unmistakably that all four, along with other cetaceans, maintain and rely on cultures—behaviours socially learned within communities—in order to thrive.

Hallmarks of social learning include imitation and teaching. Socially learned behaviour, neither genetically wired nor acquired through individual experience alone, prevails in environments and niches that vary continually but not too wildly or quickly. In highly stable environments and niches, social learning goes unneeded: behaviour genetically encoded through natural selection suffices for survival. In highly fluctuating environments and niches, on the other hand, social learning can gain no foothold: any potentially helpful culture offers no real advantage if circumstances change radically over the lifespan of a single animal.

The cetacean hunting and foraging lifestyle seem to hit the intermediate culture-favouring sweet spot, in world oceans fluctuating constantly but in discernible patterns. Meaningful and useful knowledge can propagate horizontally among peers and vertically between generations. Cetacean culture capitalizes also on mammalian big brains and social bonding, along with energy levels fueled by breathing oxygen-rich air, unlike fish.

Cetaceans originated some 50 million years ago (mya) in Sri Lanka’s general neighbourhood, diverging from even-toed ungulates (mammals with hooves), an order comprising present-day pigs, camels, sheep, cattle, giraffe and deer. Tell-tale early fossils lie in the high Himalayas, lifted there as India slammed into Asia, beginning also around 50 mya and continuing since then. The earliest known cetacean was a smallish deer-like creature spending some of its time in freshwater streams that flooded seasonally.

By and by, cetaceans learned to swim, at first in fresh water, spending more and more time chasing fish while returning to land for sleep, mating, birthing and nursing, like today’s seals and walrus. At 40 mya, some renounced land entirely and began dispersing through global seas. Their forelimbs became flippers while their hind legs shrank into vestiges. At around 35 mya, odontocetes (toothed whales and dolphins) began their voyage toward ocean’s top predatorship. Among these odontocetes, early sperm whales emerged maybe 20 mya and the notorious monster Livyatan around 10 mya. About the size of modern sperm whales, preying on whales and seals, it sported bigger biting teeth than any other animal ever. It fell extinct around 5 mya, possibly because of prey scarcity linked to global cooling, the same fate that may have met its contemporary giant shark, Megalodon. Except in size, today’s sperm whale lies closer to early odontocete forms than do other modern odontocetes like orca and bottlenose.

At 17 to 20 pounds, the sperm whale brain is the largest of any creature ever: evidence of high intelligence though her brain/ body weight ratio does not match ours. She scores high in sociability as well. We understand more and more that high intelligence in vertebrates correlates with high sociability. Nimbleness in navigating complex social spaces requires, rewards and nurtures braininess. One observer contends that sperm whales “have the most complex social structure of any animal other than man.”

Like elephants, sperm whales typically move in clusters of juveniles and mature females who share in care for the young. When mommy dives for food, she leaves her calf with babysitting female relatives. Aunties suckle one another’s babies. Such ‘alloparenting’ (caregiving to youngsters by aunties, assisting mothers) fosters sociability and intelligence by exposing juveniles to a variety of key relationships. Among nurturing females as well, networks of trust, communication and exchange of favours grow dense. Neuronal connections likewise.

Sperm whales dine mainly on squid, which they find at incredible depths. Routinely diving 500 meters, she can reach as deep as three kilometres, perhaps more, attaining dive speed up to 175 meters per minute. Abrasive squid beaks in her digestive system may be what triggers her to produce an intestinal lubricant called ambergris, a gummy, buoyant, pungently aromatic substance prized for perfumes. She excretes it in faeces and vomits. In contrast with Livyatan’s massive meat-shredding choppers, the modern cousin sports rudimentary teeth only on her bottom jaw. Scientists think she does not even use them for killing. Instead, she stuns prey with shatteringly loud buzzes, squeaks and clicks before swallowing them whole, dead or alive.

As she dives, her blood and muscles favour her with stupendous oxygen-carrying and -storage capacity, enabling her to stay down for as long as two hours without surfacing. She feeds in the deepest darkness and crushing pressure from the water above. Sound is her only useful sense in the deep she prowls. She gulps down maybe 600 squids daily, finding her prey by echolocation, like bats. Emitting recurring sonar clicks, she ‘sees’ other creatures from rippling wrinkles in the rebounding sound. Hers is probably the loudest animal sound on earth (blue whale song is its only possible rival), amplified and focused somehow through those huge spermaceti chambers in her ‘forehead’ and then echoed back through those chambers, transmitted to the brain and deciphered as imagery. (Some experts contend that spermaceti also helps regulate buoyancy.) It was of course spermaceti, prized for lubricants, lamp oil and candles, that drove humans to hunt her to the brink of extinction.

Sri Lanka is one of the best places in the world to see sperm whales because they come in close to shore here within range of whale-watching boats, and it may be the best place to see sperm whale ‘superpods’—dozens to hundreds assembled and visible at the same time. A gathering off Trincomalee in March 2012 may have numbered up to 250. Since then, superpods of up to 350 animals have appeared several times offshore in the Gulf of Mannar, mostly during March and April. Lanka may in fact be the only place on earth to witness these gatherings regularly. They may happen every year.

The likeliest explanation is mating. The whales prefer warm water for mating and maybe Lanka is especially easy for everyone to find. Calm (inter monsoonal) seas, plenty of space: Gulf of Mannar. The Gulf’s shallow waters, averaging only six meters, maybe a feature, not a bug. They obviously preclude deep-dive hunting. But I strongly suspect that the creatures go without food during the mating season anyway, though I have found no supporting sources. (Other cetacean species do fast during mating season.) The surface is where the action lies.

Because they spend so much time beneath the surface of the open ocean far from land, we know very little about sperm whales. Their first-ever underwater footage, taken in Lankan waters as it happens, came only in 1984. Once a day or so, they like to lie at the surface, amiably socializing: lying quietly side by side and nuzzling one another or ‘vocalizing (they actually lack vocal chords) back and forth. If mating is indeed the key, we may begin to grasp wild behaviors during superpods: jaw clapping, tail elevation, tail slapping, belly-ups, roll-overs, head raises, spy hopping (head up, tail down) and breaching—flinging themselves clear of the water. Flirt much?

YouTube video from Lankan waters a few years back murkily captures a savage attack by a pack of orca (killer whales) upon a grouping of sperm whales. Though the prey appears to escape after a few minutes, observers smell blood from their boat. When orcas threaten, sperm whales encircle their young or vulnerable in cooperative formation. They may face inward, presenting a firing line of powerful tail flukes outward against assailants, or they may face outward with their dangerous-toothed jaws. They protect each other and each other’s young even at high peril to themselves. Entire families will strand themselves on a beach so as to solace a stricken relative. Behavior like this leads some to call sperm whales ‘elephants of the sea.’ Their intense social bonding came to the aid of their human hunters. Where you find one sperm whale you’ll probably find several and they’ll hang with each other even in the face of obvious danger. Slaughter made easy.

As indicated, sperm whale juveniles and adult females spend bulks of their time in matrilineal pods, numbering 10-20 animals or so, all related to one another. Aside from echolocation clicks, they communicate among themselves with variable code-like click sequences called codas, each sequence lasting about a second in total. They toss these sequences back and forth in duets and join them together in choruses. This undoubtedly deepens their bonding. Youngsters learn these codas from grown-ups, along with movement and migration strategies, habitat knowledge and hunting techniques. As they mature females pass these learned behaviors along to upcoming generations of young.

Males of a certain age will depart the pod and take up with other males, often in clusters. They migrate toward the poles, leaving warm waters to aunties and juveniles, but return to the tropics for mating. Among companionate male groupings, fads of novel behaviour arise and sometimes fade away to be supplanted by others. Reminds me of my son and his buddies. Males in the Gulf of Alaska have taught one another to nibble yummy black cod off fishing longline hooks, leaving less tasty fish behind.

Aside from smallish kin-based pods and possibly non-kin-based male groups, juveniles and grown females adhere to particular multi-pod ‘clans’ numbering thousands of animals spread across huge swathes of sea. These communities share among themselves the same repertoire of codas, distinct from those of other clans. These dialects are precisely what define the boundaries between clans. Clan ‘membership’ turns not on kinship, except that within participating pods, but also not on geographical proximity. Clan members range in their smaller groupings over thousands of kilometres. They recognise and greet fellow clan members but seldom or never socialize outside their own clan. They inhabit patches of the sea alongside other clans, ignoring and avoiding those others perpetually. It’s Hogwarts without inter-house quidditch. We don’t seem to know much about whether males stick tightly with clan fellows or roam with chums from other clans.

Concomitant with their separate dialects, clans differ in their movement patterns, feeding success and likelihood of offspring. If it precludes interbreeding, such cultural separation could conceivably drive the evolution of distinct species. Separation into clans might be nature’s way of seeking Darwinian ‘fitness’ among sperm whales. Some might speculate that sperm whale clans already represent distinct sub-species. We don’t know yet and probably won’t for a long time. Speciation gets retarded to the extent that males mate outside their natal clans. They sometimes do but we don’t know how much.

Cultural differentiation seems most markedly true of Pacific sperm whales and probably applies to those clustering in Lankan superpods, given the ease of travel between the Pacific and Indian Oceans. This raises the question of how much inter-clan mating takes place in our offshore gatherings. Avoidance of interbreeding might at first glance suggest a benefit to inter-clan mating, but clans are not primarily kin-based in the first place. Mutual incomprehension among dialects might preclude mixed mating, but then again as we’ve seen, the creatures seem to have other ways of conveying erotic interest and attractiveness.

It will be a while before we can answer this question one way or the other, but I’ll venture a guess that females and juveniles populating any given superpod hail from the same clan. Whether they seek or shun males from other clans will govern any possible transition from clan to subspecies to separate species. Males compete and fight for mating opportunities. Do they gang up on males from other clans? Move along, pal, you can find your own peeps down the coast there a bit.

Braininess, sociability, cooperation and communication in distinct dialects: all seem inevitable to raise the question of language. Do sperm whales possess it? A well-funded five-year study currently endeavours to answer that question and to decipher sperm whale ‘language.’ The Cetacean Translation Initiative (CETI: a pun on both ‘cetacean’ and ‘SETI,’ Search for ExtraTerrestrial Intelligence) combines extensive recordings of communications; computer-aided pattern-seeking in those recordings; and notations on related situations and behaviour. The website coyly toggles between referring to ‘communication’ and to ‘language.’ CETI’s ultimate dream is conversing with the whales. CETI’s chief, marine biologist David Gruber, looks forward with wide eyes in a TED talk to a day when we discover sperm whales discussing something that happened ‘yesterday.’ Feel like sending money?

Understanding more about sperm whale communication seems eminently worthwhile. But the idea of learning their ‘language’ will likely end up a nothing burger. Among many theories of human language evolution, a key one posits toolmaking and tool use as the driver: the ability to transmit tool knowledge across populations and down through generations. Such would be a crucial advantage for our upright-walking, vulnerable, savannah predator ancestors. Scientists point to substantial overlap between human brain sectors governing language and tool manipulation. That whales could be substantial tool users seems vanishingly unlikely. Sperm whales can hold their breath a long time but we should not hold ours hoping to swap stories with them.

Further Reading

  • Whitehead & Rendell, The Cultural Lives of Whales and Dolphins
  • Hoare, Leviathan or the Whale
  • Beale, The Natural History of the Sperm Whale
  • Mann, Deep Thinkers
  • Pyenson, Spying on Whales
  • Melville, Moby Dick

Organizations and Resources

  • Centre for Research on Indian Ocean Marine Mammals (CRIOMM)(Sri Lanka)
  • Sri Lanka’s Amazing Maritime (SLAM)(Sri Lanka) NOAA Fisheries, National Oceanic and Atmospheric Administration (USA)
  • Whale and Dolphin Conservation (WDC)(UK) Marine Mammal Institute, Oregon State University (USA)

Whale Watching

  • Borderlands, Weligama
  • Mirissa Water Sports, Mirissa
  • Raja and the Whales, Mirissa
  • Royal Tours, Mirissa

Lawyer, writer and former law professor, Mark Hager lives in Pelawatte with his family.

mark.hager@gmail.com

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