All dolphins, porpoises, and whales are grouped together in the scientific order
Cecacea. This large order of approximately 80 living species is divided into three
suborders: the toothed whales or Odontoceti (killer whales, dolphins, porpoises,
beluga whales, narwhals, beaked whales, and sperm whales), the baleen whales or Mysticeti
(blue whales, humpback whales, gray whales, and right whales), and the Archaeoceti (a
group of fossil whales, now extinct).
Dolphins and their immediate kin are included in the scientific family Delphinidae. This family is represented by about 32 species, including some that have similar sounding names to killer whales such as pygmy killer whales (Feresa attenuata) and false killer whales (Pseudorca crassiddens). Killer whales are the largest member of the dolphin family.
C. Genus, species -- Orcinus orca
1. Because of their fierce reputation, killer whales are sometimes called ballena asesina ("assassin whale") by the Spanish. They were referred to as "whale killers" by sailors who witnessed their attacks on larger cetaceans, an over time this name was changed to "killer whales". They are called this not because they harm humans but because they kill other whales.
2. Some researcher believe distinct species of killer whales exist, especially in the Antarctic. The majority of scientists, however, group killer whales as a whole and label them all as Orcinus orca. Orcinus is probably derived from Orcus, an ancient mythological Roman god of the netherworld -- a reference to the ferocious reputation of this animal. Orca literally means "the shape of a barrel or cask" in Latin, likely due to the killer whale's body shape.
1. The classification of whales puzzled early researchers even though cetaceans roamed the ocean long before recorded history. Modern forms of both odontocetes and mysticetes appear in the fossil record an estimated five to seven million years ago. Some believe the early whales arose 55 to 65 million years ago from (now extinct) ancient land mammals that ventured back into the sea. One such extinct creature may have been Ambulocetes natans. Ambulocetes natans was discovered in Pakistan and fossil remains show a legged land animal that also feature several characteristics of whales.
The scientific order Cetacea is further
divided into three suborders: the Odontoceti, the Mysticeti, and the Archaeoceti.
2. Numerous large fossilized teeth, primarily from the Pliocene (two to five million years ago), are thought to be those of O. orca or a closely related species. One such species, O. citoniensis, is an extinct whale that had a higher tooth count and smaller size compared to modern killer whales.
3. Because whales spend their entire lives in water, they were wrongly classified as a type of fish in ancient days. Finally the Greek philosopher Aristotle (384-322 BC) correctly classified whales as mammals in his book Historia Animalium. A killer whale has more in common with a human than with a fish as both a whale and person share similar mammalian characteristics. For a example, a fish is unable to control its body temperature. A mammal, such as a whale, maintains a constant body temperature independent of its environment. Killer whales have a high body temperature similar to that of humans.
Classification|Habitat and Distribution|Physical Characteristics|Senses|Adaptations for an Aquatic Environment|Behavior|Diet and Eating Habits|Reproduction|Birth and Care of Young|Longevity and Causes of Death|Conservation and Research|Books for Young Readers|Bibliography|Index
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