Kids spied them first, sending shrieks aloft. Grownups grabbed their pre-lunch Proseccos and beat it down steps to join the admiring chorus. From the low bow deck of our rented sail yacht motoring (no wind) off Lanka’s south coast, we watched in noisy glee as the dolphins practised their ‘bow-riding’— surfing the wave pushed ahead and off to the side by the boat.
It looked a ton of fun and quite competitive among maybe a couple dozen bottlenoses. The big prize is to seize and hold position at wave’s apex, hurtling straight forward for a chill-and-thrill moment before some jostle or watery flux pushes left or right, forcing fall-off down the backward-flowing wake, followed by effortful struggle to maintain and improve placement among wriggling peers.
Bottlenoses frolic all around Sri Lanka, loving the continental shelf stretching out from beach to deep ocean slope. Organic nutrients flowing seaside from Lankan streams and swept in on favourable currents support a marine food chain second to none. Bottlenoses hold their breath and dive right down to the shelf floor when hungry enough for the buffet. In depths too murky for eyesight, they find their fishy prey through echolocation, akin to what bats do in the air.
Sound carries fast and far in water, with bottlenoses taking full advantage. From nasal cavities, they send rapid bursts of high-frequency clicks through a fluid, fatty ‘melon’ in their foreheads, which acts like a lens, focusing the sound into a directed beam. Echoes reverberate back from underwater features and objects, including fish. Echoed sound flows in through their lower jaws, also filled with fatty fluid, to their inner ears and thence to their brains, where wiring converts information into imagery comparable to sonogram. They see their surroundings with sound, using much the same brain matter devoted to vision in terrestrial animals. They may even use echoed clicks from their hunting partners to sharpen their ‘sight.’ They can pick out a ping-pong ball at 100 meters, roughly equal to human eyesight (verified by experiment on the lane with my son, Nate). With echolocation, bottlenoses can detect bones, muscle and organs, even fetuses, inside other creatures.
Their clicks rise in frequency as they close on their quarry, facilitating pinpoint accuracy as they strike.
Bottlenoses emerged 2-5 million years ago (mya). They fall into two recognized species: ‘common’ and ‘Indo-Pacific,’ the former inclined toward deep sea, the latter toward shore. Other distinct species may exist as well, with breaks between shore and deep sea populations prevailing widely. They belong to the Cetacean (whales and dolphins) sub-order, which originated some 50 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. Cetaceans claim hippos as their closest living relative. Bottlenoses fall into the odontocete branch (echolocating cetaceans with teeth), as opposed to mysticetes (filter-feeding cetaceans with baleen instead of teeth).
Tell-tale early fossils lie in the high Himalaya, lifted there as India slammed into Asia, beginning also around 50 mya and continuing since then. The earliest known cetacean, Pakicetus, was a smallish deer-like creature spending some of its time in freshwater streams that flooded seasonally. Heavy bone marrow provided ballast for ensuing forms of non-swimming freshwater waders and bottom-walkers.
By and by, of course, cetaceans learned to swim, spending more and more time chasing fish while returning to land for sleep, mating, birthing and nursing, like today’s seals and walrus. They moved downstream to deeper waters, bringing forth species adapted to diverse riverine habitats as the rising Himalaya created variegated terrain. As early as 49 mya, Ambulocetus, a slow-swimming ambush hunter sized like a sea lion, spilled into shallow seas while continuing to move ably on land, like crocodiles.
At 45 mya, Remingtonocetus improved sharply on previously-developing underwater hearing as it prowled muddy bays disfavoring eyesight. At 40 mya, some cetaceans renounced land entirely and began dispersing through global seas. Their forelimbs became flippers while their hind legs shrank into vestiges. Those who clung to land or fresh water disappeared. At around 35 mya, odontocetes split from mysticetes, beginning their deep-dive journey into echolocation. They eventually came to compete in apex predatorship with sharks dominant since when the dinosaur extinction (65 mya) swept marine reptiles into oblivion. Sometime along the way, today’s echolocating river dolphins migrated back into fresh water from the sea.
Numerous anecdotes of bottlenose intelligence require no recital here. Their brain-to-body ratio, an indicator of high intelligence, ranks among the top in the animal kingdom. Their cortical neurons may outnumber those of chimps and perhaps even rival humans. Even more fascinating is emergent science on how and why they got so brainy. As with other super-smart mammals, their story turns on social complexity, cooperativity and sensitivity. Young bottlenoses bond with and learn richly from an array of cooperating ‘aunties’ who share parental tasks, assisting actual mothers. This ‘alloparenting’ (caregiving by others than mothers) breeds emotional sensitivity among juveniles across a range of relationships, requiring and rewarding neuronal proliferation.
Meanwhile among aunties, cultivating trust relationships requires vast neuronal investment in capacities like memory, game theory, skill evaluation, situational assessment and social sanctioning. In a rare feature, females commonly live long past their reproductive years. Their long-life wisdom confers auntie benefits on juveniles and pods. That bottlenose pods fluctuate on a fission/fusion spectrum—separating and joining as circumstances vary—only intensifies pressure toward complex social judgement. Bottlenoses analyze not only how individual fellows may behave but also how different groupings may perform. Who will hunt and babysit well together under these particular conditions? Pod formation revolves largely though not exclusively around kinship. Pods coalesce around charismatic ‘socialites,’ who nurture links with other pods.
Cooperative hunting merits recognition as a bottlenose trademark. Coordinate fishing tactics include herding prey into tight balls, roundups through crescent formations, trapping against natural barriers and attack from multiple sides. In Florida, ‘driver’ bottlenoses terrify prey toward multi-dolphin ‘barriers.’ Remarkably enough, certain experts play ‘driver’ time and time again, excluding other candidates. To our knowledge, no other marine hunters anoint ‘designated drivers’ this way. Bottlenoses often assist and profit from human fishing. In Brazil they drive mullet shoals toward fishermen holding nets and eat fish that break formation.
Bottlenoses analyze not only how individual fellows may behave but also how different groupings may perform
Bottlenoses count among the few species who pass the ‘Mirror Self-Recognition’ (MSR) test. In a mirror, terrestrial mammals like chimps and orangutans can see and touch spots placed on body parts they cannot normally see (e.g. foreheads), convincingly demonstrating awareness that they are viewing their own images. Bottlenoses cannot touch spots with their flippers but they do manifest intense fascination with their mirror images. They watch themselves open their mouths, stick their tongues out, twirl, roll, blow bubbles and look at body parts. They inspect their markings closely. MSR capacity appears in species with large complex brains, high sociality and emotional empathy. Bottlenoses pass the mirror test as early as five months of age, while humans do so only at about 16 months. While this does not mean they are smarter or more empathic than humans, it does indicate high marks. They frequently offer assistance and rescue toward their own kind and toward other animals, including humans.[UH1].
Bottlenoses wield an array of whistle noises to coordinate activity, exchange information and socialize. Some experts believe this communication to be quite complex. Each individual acquires a unique ‘signature whistle’ that works as a nametag, as a locator and possibly as a signal of emotional state. Pregnant females step up their whistling as birth approaches, a behaviour called ‘fetus whispering,’ imprinting her ‘voice’ into her offspring’s memory. Intensified whistling continues for a few weeks after the birth before tapering off.
The internet lit up five years ago when a Russian scientist, no dolphin expert, claimed that bottlenoses utilize outright language, based on his whistle recordings purporting to reveal phonemes, words and sentences. Captive bottlenoses grasp at least elementary syntax, understanding the difference between ‘bring the frisbee to the ball’ and ‘bring the ball to the frisbee.’ Scepticism is in order, however. Experts on bottlenose communication quickly challenged the Russian study’s methodology and assumptions. One emerging theory of human language evolution precludes any likelihood of dolphin acquisition. Language may have emerged to facilitate transmission of toolmaking technique across generations. Language and complex manipulation draw upon much the same human brain regions as each other. No toolmaking or manipulation? No language.
Reports indicate a high incidence of illegal bottlenose hunting in Lankan waters: enforcement appears inadequate. Bottlenose meat goes to human consumption and longline fishing bait. Thriving in warm and temperate seas the world over, bottlenoses stand in no danger of extinction. If we wish them better protection, we must entertain other reasons.
Reports indicate a high incidence of illegal bottlenose hunting in Lankan waters: enforcement appears inadequate
A graduate of Harvard Law School, Mark Hager lives with his family in Pelawatte. mark.hager@gmail.com