A while back, I spent an enjoyable morning with friends on a whale-watch boat offshore from Mirissa. First came the blue whales. We would see portions of whale above the waves, then more and more whale as we closed in. Before long, up would go the broad tale, then down to disappear. We learned that we were watching three blues repeatedly diving and surfacing, ‘lunge feeding’ on balls of krill: pinkish and pinkie-sized shrimp-like crustaceans congregating in their millions along the edge of the continental shelf.
After an hour, we came in for another treat. Orcas way over there, the crew let on. We headed that way and soon picked them up: first two of those distinctive high dorsal fins, then three, then four, then five! They swam in tight formation, like jets flying wingtip-to-wingtip in an air show. That they were here while the blues cruised was no coincidence.
With the rise of Sri Lanka’s whale-watching sector, it’s now clear that orcas frequent our nearby seas. They have been spotted with some regularity off the south coast, the west coast near Kalpitiya and the east near Trincomalee. We’re just beginning to understand our somewhat surprising tropical orca. Tongue-in-cheekily, I propose calling it the ‘Indian Ocean Orca’ or ‘I.O. Orca.’ (Sorry!)
A collaborative citizen-science initiative, the Northern Indian Ocean Killer Whale Alliance (NIOKWA), uses photos to identify and count orcas from Indonesia to east coastal Africa. Reports and photos come from whale watchers, researchers, fishermen, yachties and so on. As of February 2024, NIOKWA registered roughly 67 identified orcas from Lankan waters, with perhaps nine distinguishable pods and a handful of suspected loners. From the wider Indian Ocean, it catalogued roughly 134 animals in 23 pods, with 80 dorsal fin photos. It identifies individual orcas by unique scars, tears and nicks on the dorsal fin: no two animals alike. Repeated sightings indicate that some identified orca may be Lankan residents. But sightings peak in the November-January and March-April periods when blue and sperm whales migrate through Lankan waters between the Arabian Sea and the Bay of Bengal. This suggests that orcas visit here opportunistically as part of a far-ranging foraging strategy.
YouTube footage from 2013 captures half a dozen orcas off Lanka’s south coast launching a well-orchestrated attack on five sperm whales, one of them a young calf. Voices on the video indicate that the orcas are repeatedly lunging at and biting the sperms. They mention the smell of blood and exclaim that the orcas have separated the calf from its elders, which was undoubtedly their precise intention. After half an hour of frantic confrontation some or all of the sperm whales, according to witnesses, manage to swim away in shoulder-to-shoulder formation as the orcas relinquish their attack. A strong oily smell indicates serious injury to at least one whale.
This episode marked the first documented orca attack on sperm whales in the northern Indian Ocean. When so attacked, sperm whales may take up a wheel-spoke or ‘rosette’ formation on the surface, with juveniles and other vulnerable animals protected inside the wheel. Defender heads face inwards to the centre with powerful tails radiating out, forming a fortress of flukes. Whalers called punishing sperm whale tail slaps the ‘hand of God.’ Other times, sperm whale defenders form up with tails toward the centre and formidable teeth facing outward. They may also align shoulder-to-shoulder with vulnerable pod mates behind. Expert Robert Pitman describes sperm whale defence strategy as ‘all or none:’ all out to prevent separation even though they all thereby risk injury or death. Orcas attempt to disrupt these formations by lunges, butts, bites, flanking moves, coming from below and squeezing between. They aim to terrorize, exhaust and separate. They hold prey animals under water till they drown.
Britain’s Philip Hoare, author of ‘Leviathan, or The Whale,’ dealing both with whales themselves and with Melville’s enigmatic ‘Moby-Dick,’ reported another orca onslaught back in 2017. He found himself scuba diving up close with two male sperm whales in a marine protected area near Kalpitiya. It was mating season, a time of spectacular ‘superpod’ sperm whale gatherings in Lankan waters. He noticed their erections. Suddenly they raced off along the coastline. Hopping back in his boat, he gave chase with his two companions, thinking they might witness a mating event, but soon learned that the creatures were responding to a very different kind of signal: distress. They joined some 30 other combat-scarred males protecting juveniles and females from an aggressive eight-member orca pod on the prowl.
The defenders switched formation from line to rosette and back again. They spewed reddish poo to confuse and nauseate the orca. They manoeuvred to place the boat between themselves and their assailants. After an hour or so, the sperm whales managed to slip away without fatalities, as fast as they could drag their youngsters along. The orcas circled the boat for a time, then formed up and swam rapidly right at it. Hoare imagined possible tipping or swamping by frustrated and enraged killer whales. At the last instant, they dove in unison under the boat. A warning? Hoare and boatmates fled the scene on the double-quick.
Meanwhile, there’s no doubt that orcas also hunt blue whales in Lankan waters. In 2014, observers encountered a blue whale, “thin and apparently unable to dive,” with serious injuries characteristic of orca attack: extensive rake marks from teeth, gaping flesh wounds on flank and abdomen, flippers gashed with one tip missing, dorsal fin torn off. Blues flee at high speed from attacking orcas, while orcas attempt to wound them into weakness. Orcas will bite and hold onto flippers, dorsal fins and tail flukes to slow their prey down. They may snack without killing their prey outright. But they dearly want the kill, for a particular cuisine item mentioned below.
Little is known about tropical orcas, as opposed to well-studied ones who inhabit chillier seas. Some scientists deem I.O. orcas on the skinny side, a clue perhaps to challenges they face in finding food. Experts suspect that they forage widely and opportunistically, rather than specializing in one abundant prey food like many orcas elsewhere. Two orcas spotted together here have also been sighted near Abu Dhabi, over 3300 kilometers away. This huge range further suggests serious difficulty in making a living.
Orcas have been lauded as Earth’s most astonishing animals. One scientist suggests that they were ‘brainiacs’ of the planet for 10 million years or so before humans appeared 200 thousand years ago. Sometimes called ‘wolves of the sea,’ they manifest a high degree of social learning, described by scientists as heavily ‘cultural’ behaviours. They teach complex foraging strategies to their young. They spend their lives in tight-knit pods embedded within defined clans and larger distinct communities. Pod members appear to communicate among themselves in ‘dialects’ varying from those of other pods living nearby. Separate pods tend to ignore one another. Mutual communication may fail due to differing dialects.
Though the orca is generally considered a single species, research has shown that they occur in different ecotypes, or races if you will, possibly distinct from one another genetically, and specializing in certain habitats and types of prey. Some, for example, dine almost exclusively on a single species of salmon, while surrounding waters abound in many kinds of fish and other potential prey. Some scientists suggest that orcas should be classified into separate subspecies and maybe even different species.
Orcas operate in matriarchy, with mature females, especially elderly ones, providing guidance and leadership. They number among very few non-human animals to live through menopause. Avoiding energy-sapping pregnancy and nursing, menopause extends female lifespan far beyond reproductive years so that accumulated knowledge and experience get conserved to benefit children and grandchildren. This proves especially crucial for mature males who remain strikingly ‘immature,’ deeply dependent emotionally and physically on their mothers. The longer Mom lives, so her sons. If she dies, they will likely follow soon thereafter. She steers them away from danger and even feeds them fish they can’t be bothered to chase for themselves. By keeping them going, Mom passes her genes along to more and more of their offspring, her grandkids.
Orcas share kill amongst themselves after cooperative hunts. Some will swim in synchronized fashion toward a seal perched on an ice floe. This creates a wave that tips the floe and plunges the seal into the water where orcas dismember it. Or simply fling it around in play. Orcas herd evasive herring into tight balls where they can be whacked by powerful tails. Hugely adaptive, orcas range across all oceans, the second most widely distributed mammal on earth, after humans. Their fearsome hunting may lie behind past extinctions of multiple marine mammals.
Under normal circumstances, healthy orcas never fall prey to other animals, not even great white sharks. Try snatching that scrumptious-looking orca calf from its pod and see what happens to you. Orcas terrify great whites into speedy flight. They know how to flip sharks upside down, sending them into a poorly understood stupor called ‘tonic immobility.’ Orca will then excise and eat only the prey’s fatty liver. Hopefully, the shark feels nothing in its brief remaining moments.
There’s no record of orcas ever attacking humans for purpose of feeding. We’re not chubby enough. They have killed or maimed several aquarium handlers, however. Maybe they dislike doing silly tricks to get a meal.
Orca social learning entails complex planning, demonstration and rehearsal. In South American Patagonia, pups learn to hunt both at water’s edge and farther out. Mommies demonstrate how to ride a breaking wave onto the beach to snag unwary seals, then using the next wave swell to wriggle back into deeper water. Pups then practice the counter-instinctual strand-wait-wriggle manoeuvre time after time. When Mommy snatches a baby seal, she releases it over and over so that pups gain skill catching it in offshore waves.
Orcas practice ‘fads’ of play activity such as tormenting porpoises, pulling sea kelp down to watch it spring back up when released, or wearing ‘hats’ of dead salmon on their heads. In and around the Strait of Gibraltar, orcas have recently made a habit of biting off chunks of rudder from fishing boats and sport craft. Several boats have flooded and foundered due to punctured keels. This could be another orca play fad. Or maybe orca have deduced that proliferating boats threaten their fish supply.
‘Culture’ can be inferred when different groups within a species behave differently (e.g., some orca pods eat only salmon while others insist on seals) and this variation cannot be explained by divergent genes or environments. Social learning thrives where an animal’s habitat falls in an intermediate zone of variability. If the pertinent environment rarely varies, social learning will not evolve: genetically-driven instinct will do just fine. On the other hand, if an environment varies wildly—chaotically and without discernible patterns—social learning is impossible and useless. Social learning emerges when an environment varies in partially patterned fashion so that judgment and decision based on experience help animals thrive. It requires life spans long enough for transmitting and retaining knowledge and skills. The marine hunting lifestyle of odontocetes–toothed cetaceans (whales and dolphins) like bottlenoses, orca and sperm whales–seems to fill the bill.
Some experts trace this success in social learning precisely to the fact that cetaceans are mammals. Having evolved originally on land, cetacean ancestors (cousins of today’s quasi-aquatic hippos) colonized the seas upon the mass extinction of dinosaurish marine reptiles, which had previously occupied key niches. Cetaceans went to sea pre-equipped with tools favourable to social learning: lungs for breathing oxygen-rich air, large brains, good hearing, warm blood for high energy budgets, and strong social bonds radiating outward from the mother-child bond.
A positive feedback loop for braininess and social learning took hold. High oxygen use facilitated warm blood, high activity levels and big brains. Watery surroundings pushed cetaceans toward single-calf birth because larger-size offspring can better withstand heat loss. Single-calf births intensified mother-child bonding. Good hearing and good vocalization due to air breathing fostered complex communication. Odontocetes used the sound-favouring properties of water to develop hearing into a virtual ‘sixth sense’—echolocation—broadly akin to that of bats. By vocalizing and hearing contours in the bounce-back, orcas and other odontocetes ‘see’ their surroundings with intricate detail through sound.
Orcas hunt blue whales whenever they can, sometimes successfully, sometimes not. Blues can hit swim speeds orca cannot match. Events in southwest Australia may signal novel evolutionary chapters for both predators and prey. Blues linger over a sea canyon or shelf edge, hoping for cold water ‘upwellings’ from the deep. That cold water is rich in both oxygen (density grips it) and organic nutrients from the seabed, washed off the land or drifting down from decomposing marine life (‘marine snow,’ it’s called). With upwelling, oxygen and nutrients rise toward the sun-warmed surface. Photosynthesizing micro-plants bloom luxuriantly, food for microscopic animals. These tiny organisms feed massive outbreaks of krill. That brings blue whales in for the buffet (‘Today, I think I’ll try the…krill’). Orcas flood the zone to hunt them. Comparable conditions prevail off Lanka’s south coast, explaining why we would see both blues and orca on a single whale-watch trip.
Over the past few years, southwest Australian whale-watch tours have witnessed multiple orca attacks on blues. In the most spectacular one, up to 70 orcas coordinated in a three-hour mobbing of a lone blue. Some would chivvy the prey while others rested between their turns. They killed it in the end of course. Orcas frequently consume only blue’s fatty tongue, leaving the remaining carcass to scavengers.
A striking feature of this hunt is that it must have involved cooperation among multiple orca pods, which rarely number more than, say, 15 members. Such cross-pod cooperation is one item of evidence against the multiple-species theory of orcas mentioned above. In any case, if multi-pod hunts become a trend, blue whales may face accelerating predation, first in the Indian Ocean perhaps, then perhaps elsewhere. This could limit the recent rebound in blue whale numbers since the world whaling ban came into effect, only after decades of human hunting drove blues to the brink of extinction. They remain officially endangered. One thing to worry about for sure: orcas learn fast….
Author, lawyer and former law professor, Mark Hager lives with his family in Pelawatte. [email protected]; https://www.linkedin.com/in/mahager/
Organizations
Center for Research on Indian Ocean Marine Mammals (Sri Lanka)
Wildlife and Nature Protection Society (Sri Lanka)
Indian Ocean Marine Mammal Research and Conservation Unit (Sri Lanka)
Center for Whale Research (U.S.)
Marine Mammal Institute (U.S.)
Indian Ocean Marine Research Centre (Australia)
Marine Mammal Research and Conservation Network of India (India)
Further Reading: Sri Lanka
Gemmell, Killer Whale (Orcinus Orca) Predation on Whales in Sri Lankan Waters
Hoare, An Extraordinary Battle Between Sperm Whale and Orcas—In Pictures
Further Reading: General
Hoare, Leviathan, or the Whale
Hoyt, Orca: The Whale Called Killer
Mapes, Shared Waters, Shared Home
Colby, How We Came to Know and Love the Ocean’s Greatest Predator
Neiwert, Of Orcas and Men: What Killer Whales Can Teach Us
Riggs, Killer Whales (Ages 6-8)
‘Aquatic Mammals’ journal