Killer Whale Evolution
Killer Whale Ancestors
Killer whales are the only species in the genus Orcinus. In 1758, the Swedish naturalist Carl Linnaeus included this marine species in his book “Systema Naturae” setting the ground for further research on this and other cetaceans.
The “Orcinus orca” belongs to suborder Odontoceti also known as toothed whales, which differentiates them from the baleen whales. The Delphinidae family to which they belong, also includes dolphins, false killer whales and pilot whales.
Scientists think that all whales, porpoises and dolphins probably descended from carnivorous land animals that were part of the fauna 60 million years ago, during the Paleocene. These animals are known as Mesonychids and using the latest technology, and their fossils researchers recreated their possible appearance. The relationship between those land animals with modern orcas is evident in the teeth, skull and other morphological structures.
The Mesonychids were similar in size to a wolf, but their feet were ungulates. Looking for food they started getting deeper into the water and in an evolutionary process that took millions of years, they developed fins, lost the fur, and the shape of their teeth modified until they reach an anatomical design fully adapted to marine life.
Moreover, alternative scientific research claims that cetaceans are closely related to hippopotamuses. The Cetartiodactyla is a clade where cetaceans belong that relate them with artiodactyls. Scientists think that hippopotamuses are the clearest example of how cetaceans could have been when they inhabited the earth, but evolution changed them to be what they are today.
In more modern times, it is said that the name of killer whales was a mistranslation made by Basque whalers who saw a group of these species capturing its prey in a very ingenious way. Lately the term “killer” is avoided by conservation groups, because it can be misinterpreted the behavior of these animals by humans; therefore, they prefer to call them “orcas.”
There are other cetaceans that are related to orcas in some ways, but they are morphologically different, and they are distributed only in some regions of the world. These are the false killer whale (Pseudorca crassidens), pygmy killer whale (Feresa attenuata), the pilot whale (Globicephala melas), the finned pilot whale (Globicephala macrorhynchus) and melon-headed dolphin (Peponocephala electra). Some of these species are not fully researched, but they share some similarities with Orcinus orca.
Among orcas there are several sub-populations that differ in color designs on the skin, diet, social patterns and anatomic features. Some scientists think that there are up to three subspecies, which developed different behaviors and habits due to their need to adapt and survive in their specific environment. This hypothesis is still on discussion, and further research is currently on progress by specialists that are trying to find conclusive evidence.
A question that might come to your mind after reading this article is whether killer whales will continue to adapt to environmental changes that the earth is suffering today, as a result, of global warming. Are these subspecies or sub-populations the beginning of adaptation to this? Will orcas change their appearance in the future? That is something that only evolution can answer.