We have come to document very long displacements : gray whales have traveled 25,000 km and humpbacks 18,000 km. Scientists have always thought that it responds to two basic calls, feeding and mating . In the months of June-July they go to polar areas in search of food while in January-February they return to Ecuador to mate . Some biologists think that they return to warm areas after giving birth, but there is no consensus on why they have to make such long journeys when they can feed and have their young in the same place. One of the explanations that are handled is that it is an ancient memory: whales evolved in warm waters, which had high concentrations of plankton and fish. Due to plate tectonics, the ocean currents changed and carried plankton and small fish with them, forcing the whales to go after them. And then to return to Ecuador for reproductive reasons.
Nor do we know how they navigate their very long migrations . When magnetite crystals are found in the tissue of some species of whales, such as humpbacks, biologists suggest that they could navigate using variations in the Earth’s magnetic field . This would explain why, for example, solar storms disorient them. However, this does not seem to be the complete, or at least valid, explanation for all cetaceans. Other researchers reveal that blue whales use their memory to go to and from their feeding grounds . What is not clear is how young that have never been in the feeding areas are able to reach them: do their mothers teach them? This is what Argentine scientists who study the migrations of southern right whales off their coasts believe.
The other great mystery of whales is their ‘song’, a term that is popularly used to describe the pattern of sounds they emit, the duration and intensity of which depends on the species to which it belongs. We all know that whales ‘sing’, something that has been used even in science-fiction movies like Star Trek: Mission Save the Earth, but not all whales do.
The reason why they sing is varied : from its use as an echolocator to love songs, to saying where they are or, simply, announcing that there is an open self-service where to eat. Surely we are not going too far off the mark in supposing that these are the reasons, but what we are not so clear about is the reason why they are so complex, especially in humpback whales : by studying their musicality, melodies and rhythms have been distinguished , and his “compositions” evolve over time as if they were variations on an original piece.
Of all the species of whales, the humpback is the one that would become part of the list of the forty main animal song: they have a complex and organized song in which a main theme composed of phrases and subphrases that is repeated can be distinguished. several times in a row . In the case of the blue whale, it has been discovered that its song is seasonal : the intensity of the song increases during the summer and early autumn to reach its peak in November; then it decreases rapidly between December and January, and reaches its lowest point between the months of February and June. In addition, from August-September (late summer) the number of nocturnal whale songs increases, which decreases around November. At the beginning of winter (December-January) songs become more common during the day. That is, when whales migrate to warmer waters, singing is essentially a diurnal activity.
At first it was thought that each population of humpback whales interpreted their own repertoire more or less faithfully to the original, but biologists have discovered something that we could call ‘musical exchange’ : in 2011, and after a decade of recordings and study of the behavior of six different populations of humpback whales in the Pacific Ocean, from Australia to French Polynesia, it was discovered that the song of a population of whales in eastern Australia began to hum three years later a different population and far away from them , and that it had gradually passed through the intermediate populations. But why are songs ‘copied’? One more mystery.
On the other hand, in the whale family -the most abundant and diverse of all, which includes the blue, sei or boreal, bryde and humpback whales- we find different dialects: in the Eastern Pacific the sounds are quite different from the of those that live in the western region, and in the Atlantic the repertoire is very different from that of the Indian. This makes some biologists think that we are dealing with living ‘languages’, which evolve and develop.
Finally, to all these mysteries we must add another that has surprised scientists: for some unknown reason, in March 2017 a group of around 200 humpback whales congregated off the South African coast . And no one knows why a solitary animal like that, which at most gathers in groups of a maximum of 7 individuals, formed such a supergroup.
