Nothing…nothing…THERE!! A distant white smudge blurs a space on the horizon: spray from a blue whale coming to surface. Our boat moves toward it and soon we can see more and more whale above the waves. Biggest animals ever, blue whales abound on Lanka’s southern porch. I spent a morning on a boat, watching as three blues dove, tails up, then re-surfaced minutes later, spouting exhalations to catch their breath. They were foraging and dining on balls of krill: thumb-size orange crustaceans congregating in their millions along the edge of the continental shelf. Krill is virtually the entire blue whale diet.

A typical blue feeding dive is an athletic and physiological marvel. Strokes from huge tail flukes power her downward against her own buoyancy through the first 25 meters. As she descends, pressure from the water above forces her flexible rib cage inward, decreasing her volume and increasing her density so that her buoyancy dissipates and she begins to fall rapidly with gravity toward the sea bed. She turns and heaves herself upward in a strenuous lunge through krill balls, fighting not only gravity but also the hydrodynamic drag created by her own gaping jaws. She shudders to a halt, having gulped maybe 60 tons of seawater. With a gelatinous tongue the weight of an elephant, she spews the water out through her baleen—cartalaginous sieves that line her mouth—retaining countless krill then to swallow. She does this all again and again, upward toward the surface, holding her breath all the while of course. After gasping in the waves for several minutes, her tail goes up again in her next dive.

Lankan waters teem with organic nutrients washed from the rain-drenched land. They sink by the ton into cold deep waters just beyond the shelf. Winds sweep surface water away in mighty currents and this pulls oxygen-rich, nutrient-laden cold water up from the deep in a process called ‘upwelling.’ When sunlight hits this fertile slurry, photosynthesis goes crazy. Tiny plants called ‘phytoplankton’ grow and multiply by the billion. Micro-animals
(‘zooplankton) dine on this sumptuous buffet and likewise proliferate. Feeding on both, krill blooms turn the sea to orange.

That, in a nutshell, is why blues visit Lankan waters. Science is learning more and more about how these astonishing animals came to exist in the first place. Part I of this essay, published in the November, 2023 issue of ‘Echelon’ and re-posted on my LinkedIn page specified below, recounted the first five of eight key evolutionary stages. In this Part II, I recount the remaining three.

Six: Supersizing

Global cooling that began 15 mya accelerated sharply around five mya due to ocean current changes triggered by tectonic events, chiefly the volcanic rise of Central America, closing a sea passage between North and South America.

As cooling continued, non-tropical latitudes saw the onset of Ice Age glaciation. Glaciers scraped iron and other mineral nutrients from continental rock and released them into ocean during summertime meltbacks. These nutrients found their way into coastal pockets like shelves, bays, inlets and estuaries. There they met organic nutrients in oxygen-rich cold water upwellings where sunlight induced great blooms of photosynthesizing phytoplankton and concomitant zooplankton surges. Poo and decomposing lifeforms stoked blizzards of organic ‘marine snow’ falling into frigid depths, thereafter to surface again in organically-enriched upwellings.

Within these positive feedback loops, dramatic explosions in ocean productivity could appear and then vanish quickly in particular localities, driven by temperatures, winds, currents, upwellings and other vagaries. Rorquals supersized to exploit this new but evanescent cornucopia, yielding our modern blue whale among other giants.

Vast blooms of krill and other small animals augmented the advantages of lunge feeding. Increased food supply enabled increased size. Increased size fostered higher nutrition storage in blubber and allowed for longer migrations in search of blooms that might be separated by hundreds, even thousands, of kilometers. It also favored winter travel for calving and breeding in the tropics and reverse summer travel from tropics to cold water feeding grounds. Size, along with streamlining, allowed faster swimming for migration and pushed lunge-feeding efficiency upwards.

Supersizing fed upon itself, generating its own feedback loop. Upsized rorquals needed bigness to find food enough to be big. (Therein lay a hidden vulnerability, to be explored below.) By a couple million years ago, today’s blue whale emerged and proliferated with a diet featuring some of the tiniest crustaceans in the sea. Feeding low on the food chain, krill on the species level command huge energy budgets, giving them possibly the highest total body mass in the multicellular animal kingdom. Industrial-scale krill binges in turn furnish blues the huge energy they need to grow, forage, migrate and reproduce.

Seven: (Sub)-Species Fraternitas

Controversy could easily arise as to whether blues today constitute a single species or more than one. Currently classified into four or five sub-species, blues may someday with advancing knowledge get re-grouped as two or more separate species. Obviously, blues are very difficult to study. At present we do not know enough about their genes and habits to be sure about their population interrelationships.

There are numerous approaches as to what science should mean by a ‘species.’ A leading approach posits that it means a population of animals capable of interbreeding and producing fertile offspring. Varying approaches apply as well to the question of what makes ‘speciation’—splitting of one species into two or more—happen in evolution.

Scientists understand ‘allopatric’ speciation to occur when breeding populations get separated by a geographic barrier—a mountain range perhaps—and cease to interbreed. Genetic drift and differing habits over a long time make it impossible to interbreed fruitfully. ‘Sympatric’ speciation occurs in the absence of geographic barriers when breeding populations occupy contrasting ecological niches and fail to interbreed long enough to make it impossible when they happen to encounter one another.

Either of these scenarios could potentially apply to blues. The recognized subspecies occupy by-and-large separate zones in the world’s oceans. Sheer distance is a form of separation and there may be invisible barriers to blue whale travel in the world’s seas. The rareness of crossing through the tropics between north and south may indicate one such barrier. Sharp frontiers between cold and warm or salty and less-salty water near Antarctica may represent additional ones. Already there are whispers of multiple species among orca, another charismatic cetacean found in Lankan waters. Long distances and differing diets may keep orca populations genetically separated.

The prevailing classification recognizes two blue subspecies operating heavily in Lankan seas: Pygmy Blues (‘pygmy’ being a relative term here) and North Indian Ocean Blues. Whalers noticed no difference between them and some scientists agree that there is none. Others, however, insist on a distinction, contending for example that they breed and calve with opposite seasonality.

Antarctic Blues graze in frigid southern waters except for dashes toward the Equator for calving and breeding. Some think they would have next to nothing to do with Lankan whales or possibly any other subspecies. Sharp divides in water temperature and salinity in southerly seas may keep Antarctic Blues isolated. Experts contend that Lankan blues never visit the Southern Ocean though bits of evidence suggest that they sometimes might.

So-called ‘Madagascar’ Pygmies live so far from ‘Australian/Indonesian’ Pygmies that encounters between them would be few and far between. ‘South Pacific’ or ‘Chilean’ Blues live far from any other subspecies except Antarctic Blues, with which they may not interact. Similarly, ‘Northern’ Blues in the Atlantic cannot be breeding with those in the Pacific. We’ll probably never know whether they could.

Also worth considering is that Earth’s blues belong to around a dozen different male song-style groups. Without getting into the weeds on how these mating song groups map onto the recognized subspecies, the point is this: if females fail to respond to songs that are wrong for them, would this not create breeding barriers? World blues may even turn out to represent a version of so-called ‘ring species,’ whereby population A can breed with B and B with C, but A and C cannot successfully interbreed. Would A and C still be one species or are they now two?

Complicating matters further, a phenomenon occurs quite opposite to possible speciation among blues. It turns out that blues sometimes breed with fellow-rorqual fin whales, resulting in hybrid offspring. One such offspring has been found carrying a fetus, which indicates fertility in the mommy. Do fins and blues now count as two subspecies within a single species?

Widespread evidence of such hybridization would tend to cancel my whole discussion of speciation and pose questions a new over what science should mean by ‘species.’ Experts recently contend that hybridization has played a major role in overall rorqual evolution. Fin whales recently moved off the ‘endangered’ list, re-classified as merely ‘vulnerable.’ Interbreeding with them may be a blue whale way of dodging imminent extinction. We obviously have much to learn about rorqual speciation.

Eight: Extinction?

Until the 20th century, blues largely evaded the harpoon. They swam too fast for the whaling craft and they don’t tend to cluster. But the 20th century brought faster ships and cannon-launched harpoons detonating upon impact. Blues then met with epic slaughter.

Blubber came into use for lamp and cooking oil, soap, candles, perfume, cosmetics and margarine. Baleen (so-called ‘whalebone’) made its way into corsets, umbrellas, handles of various kinds and brushes. Meat turned up in kitchens.

An estimated 350,000 blues succumbed to whaling in the 20th century’s first half. Antarctic blues suffered especially, losing perhaps 99% of their numbers. As they became harder to find, whalers zeroed in on the Arabian Sea, a key range for Lanka’s blues. By the early 1960s 80% of hunted blues were sexually immature. Earth’s blue population may have fallen below 5000 animals.

The worldwide whaling ban seems to have saved blues from prompt and total annihilation. Numbers have slowly rebounded, reaching an estimated 10 to 25 thousand today. Blues still hover on the brink of extinction, however, rated as ‘endangered’ (highly likely to fall extinct in the near future) under U.S. law and by the International Union for Conservation of Nature.

Endangerment begins with specialization in large size and lunge feeding on very specific prey. ‘Generalist’ species face less extinction risk than specialists do, because generalists can occupy a broader range of niches. Small animals, with lesser food and range requirements, face less extinction risk than big ones, which is why bird-like dinosaurs survived the extinction event tragically befalling their outsized cousins.

Ocean warming may threaten blues by reducing cold-water upwellings that bring krill blooms. Studies link warming with an 80% Southern Ocean krill decline over the past 40 years. Food supply may also suffer from commercial krill harvesting. Acidification that goes with ocean warming may also impact krill populations by hampering shell formation.

Reduced blue populations could yield demise from a single cataclysm, disease for example. Wide separation of populations could lead to inbreeding, inducing declines in genetic diversity and heightened vulnerability to disaster. Slow reproduction cycles (lasting at least three years) will retard population rebound. Plastics and toxins lodge in blubber and stomachs with consequences unfathomable. Cetaceans get entangled in fishing gear, hampering mobility.

Orca predation may pose a threat, not least in nearby seas. Orcas hunt blues in packs ranging from a few animals up to dozens. They bite and bleed their prey into exhaustion before ganging up to hold them underwater till they drown. They often swim into the mouths of their blue victims, eating only the fatty tongue, leaving the remaining carcass to others. All this has been verifiably observed in the Indian Ocean only recently. Orcas learn fast. If such predation grows commonplace, watch out. Some 25% of blues around Mexico’s Baja California bear scars from orca attacks. Orcas prey most heavily on young blues. Collapse of other prey populations (fish?) could lead to heavier orca predation on blues and other cetaceans.

Some observers suggest that blue populations sustain heavy damage from ship strike: fatal impact from heavy, fast-moving vessels. Blues cruising along Lanka’s southern continental shelf sometimes get killed by super-tankers steering through the same zone. It seems unlikely that ship strike sharply depletes worldwide blue numbers in the short term. More plausible is that it would deplete local populations in places like Sri Lanka, coastal California and the Gulf of St. Lawrence. Short-term local depletion could lead to long-term sustainability failure. Sri Lanka is currently reviewing whether shipping lanes should be mandatorily moved further offshore to protect whales. This could bring revenue loss for Sri Lanka due to fewer stop-ins for refuelling and other services. In 2022, the Mediterranean Shipping Company, the world’s largest container shipper, announced an offshore route shift and speed slow-down in southern Lankan waters.

Ocean noise poses perhaps the most insidious threat blues and other cetaceans may face. Sound is crucial to cetacean life, with roles in mating, rearing offspring, food-finding, navigation and group coordination. Ocean noise could disrupt these functions in complex ways. Harmful noise may stem from seismic surveys for sea-floor mapping, mining and hydrocarbon exploration. Low-frequency sound from ship propellers overlaps in range with blue whale mating calls. Blues flee from sonar, which may cause trauma (e.g. bleeding from ears and eyes), interfere with feeding and mating, and produce panic leading to strandings. Sonar may also cause overly-rapid surfacing with concomitant decompression sickness (due to nitrogen bubbling in bloodstreams, the ‘bends’). Decade by decade our seas grow noisier.

Extinction is the rule, not the exception. At some point, blues will inevitably fall extinct, as will we. Given our role in their demise, we surely should do what we can to prolong their run. Given their sheer magnificence, we should get out to see them while they’re still here.

(Writer, lawyer and former law professor, MarkHager lives with his family in Pelawatte.mark.hager@gmail.com; https://www.linkedin.com/in/mahager/)

Further Reading

• Small, The Blue Whale
• Zimmer, Fish With Fingers, Whales With Legs
• Rice, Marine Mammals of the World
• Berta, Return to the Sea
• Whitehead & Rendell, The Cultural Lives of Whales and Dolphins
• Mann, Deep Thinkers
• Pyenson, Spying on Whales
• Martenstyn, Out of the Blue

Organizations and Resources

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

Whale Watching

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