Once upon a time in the Eocene epoch of our blue planet whales were quadrupeds. “The world is fixed, we say: fish in the sea, birds in the air. But in the mangrove swamps by the Niger,” writes Loren Eiseley in The Immense Journey, “fish climb trees and ogle uneasy naturalists who try unsuccessfully to chase them back to the water. There are things still coming ashore. ”
The truth is, observed Eiseley, there is nothing normal about nature.
Marine biologists in Brazil were stunned to discover that on Friday a young 10-ton humpback whale had washed ashore on a remote, forested island near the mouth of the Amazon River, some 4,000 miles from its expected Antarctica summer feeding grounds, a baffling discovery that has stumped the scientists who found it. Although tens of thousands of humpback whales are estimated to live in the Atlantic Ocean off Brazil, nearly all of them have migrated south by this time of year.
Except for one. Why?
“At this very moment, two spacecraft move at over thirty-four thousand miles per hour, about ten billon miles away from us, each carrying a gold-plated copper record. The spacecraft, Voyager 1 and Voyager 2, are meant as messengers: they carry information about our address in the solar system, the building blocks of our scientific knowledge, and a small sampling of images, music, and greetings from around the world. They also carry whalesong,” reports Nick Pyenson, a paleobiologist and the curator of fossil marine mammals at the Smithsonian.
Whales, Pyenson says, are almost a human dream of alien life: approachable, sophisticated, and unscrutable. A click train from a sperm whale a mile deep may convey thoughts about where lunch is located or the meaning of the universe—we cannot tell or know the difference because the meaning of their language is lost without knowing the context.
In his debut book, Spying on Whales: The Past, Present, and Future of Earth’s Most Awesome Creatures, Pyenson predicts how whale species will respond to burgeoning ecological pressures. “His examination of the anatomy of present-day cetaceans (whales, dolphins, and porpoises) takes us back to the evolutionary origins of these ocean-borne mammals. What roamed then proves to be an astounding array of real chimera, as evocative as any marine monster of myth or fiction,” writes Rebecca Giggs in The Atlantic.
Since the mass extinction at the end of the Cretaceous, observes Pyenson, “the ecologically dominant ocean invaders have been mammals—including everything from whales to sea otters. All of today’s marine mammal lineages are distantly related to one another, whether it’s a whale, a sea otter, a seal, a sea cow, or a polar bear (yes, technically polar bears too, which eat seals and hop across ice-covered seas).
Throughout 50 million years of whales existence, extinction dominates as a constant background theme because, as with the vast majority of animal lineages on the planet, most all the whale species that ever evolved are now extinct. While they are the most diverse marine mammal group today, numbering over eighty species, the fossil record documents over six hundred whale species that no longer exist.
Whale hearing, sight, smell, and taste are all senses that evolved for nearly 300 million years on land before the first ancestors of whales took to the sea.
“Members of the conservation group Bicho D’Água,” reports reported Matthew Haag in The New York Times, “found the whale after following vultures that were circling a mangrove on the island in the Amazon, Marajó Island, the group said. About 50 feet from the shore, scientists spotted the lifeless humpback — about 26 feet long — lodged in thick shrubs and brush. It had been dead for at least several days, government officials in Pará, a state in northern Brazil, told local news outlets.”
“We imagine it was floating and the tide took it into the mangrove,” Renata Emin, the president of Bicho D’Água, told the Brazilian news site G1. “The question is, What was a humpback whale doing in the month of February on the northern coast of Brazil? It’s unusual.”
Naval sonar has been linked to mass strandings of otherwise-healthy whales for nearly two decades, but the precise mechanisms of how it affects whales has eluded scientists. Now, reports Mindy Weisberger, Live Science researchers have explained key details of how this disruptive signal triggers behavior in some whales that ends in death.
Mass strandings of Cuvier’s beaked whales (Ziphius cavirostris) were almost unheard of prior to 1960, but that changed with the introduction of midfrequency active sonar during naval exercises in the pelagic ocean. This type of sonar, developed in the 1950s for submarine detection, operates in a range of 4.5 to 5.5 kHz, according to the study. After this sonar appeared, mass stranding events soon skyrocketed for beaked whales, reports Live Science, with 121 such strandings taking place between 1960 and 2004, the researchers wrote.
So, what was it that drove the Amazon humpback to it’s return to land and death? Was it sonar disorientation? Disease? A dim memory, a faint longing for its evolutionary place of origin? Or a premonition of its species fate in the Anthropocene Epoch?
Image credit: With thanks to blueocean.net