Killer Whales are cetaceans which belong to the order Delphinidae. This means that they are “Dolphins” regardless the word “whale” is in its name. 2. As consequence, Killer Whales are the largest dolphin. 3. Orcas are called Killer Whales because they feed on several other marine mammals, like seals or dolphins, not because they kill people. 4. Killer Whales are aquatic mammals. They nurse their babies with milk from their mothers. 5. As mammals, Killer Whales need to breathe air from the top of the ocean, they cannot breathe under water like fish. 6. Killer Whales are very good swimmers. They are capable to travel up to 30 mph. and reach deep waters. 7. Killer Whales eat up to 5% of their body weight each day. This averages out to over 500 pounds of food for each Killer Whale. 8. Killer whales are grouped in pods, the base of their social structure formed by 6 to 40 individuals. 9. Killer Whales gestation period is around 16 to 17 months and they usually give birth to only one calf. 10. While some accidents have occurred with Killer Whales in captivity, there isn’t any record of a killer whale attacking a human. 11. Killer whales have a unique mark behind its dorsal fin. These marks help scientist to distinguish each Killer whale while researching. 12. Killer whales communicate through different vocalizations specific to each pod. 13. Killer whales are found in all oceans in the world, but most of them are found in cooler waters. 14. Killer whales brain is five times larger than humans. They are very social, intelligent, and curious. 15. Killer whales spend 60% of their time foraging for food. 16. Killer whales do not migrate, but they have been known to travel hundreds of miles to find fresh food. 17. The life expectancy of a killer whale in the wild is 50 - 60 years for males, and up to 90 years for females, however, killer whales in captivity live less than 30 years. The killer whale (Orcinus orca), also referred to as the orca whale or orca, and less commonly as the blackfish, is a toothed whale belonging to the oceanic dolphin family. Killer whales are found in all oceans, from the frigid Arctic and Antarctic regions to tropical seas. Killer whales as a species have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammals such as sea lions, seals, walruses, and even large whales. Killer whales are regarded as apex predators, lacking natural predators. Killer whales are highly social; some populations are composed of matrilineal family groups which are the most stable of any animal species.[5] Their sophisticated hunting techniques and vocal behaviors, which are often specific to a particular group and passed across generations, have been described as manifestations of culture.[6] The IUCN currently assesses the orcas conservation status as data deficient because of the likelihood that two or more killer whale types are separate species. Some local populations are considered threatened or endangered due to prey depletion, habitat loss, pollution (by PCBs), capture for marine mammal parks, and conflicts with fisheries. In late 2005, the southern resident population of killer whales that inhabits British Columbia and Washington state waters were placed on the U.S. Endangered Species list. Wild killer whales are not considered a threat to humans,[7] although there have been cases of captives killing or injuring their handlers at marine theme parks.[8] Killer whales feature strongly in the mythologies of indigenous cultures, with their reputation ranging from being the souls of humans to merciless killers. Orcinus orca is the only recognized extant species in the genus Orcinus, one of many animal species originally described by Linnaeus in 1758 in Systema Naturae.[9] Konrad Gessner wrote the first scientific description of a killer whale in his Fish book of 1558, based on examination of a dead stranded animal in the Bay of Greifswald that had attracted a great deal of local interest.[10] The killer whale is one of 35 species in the oceanic dolphin family, which first appeared about 11 million years ago. The killer whale lineage probably branched off shortly thereafter.[7] Although it has morphological similarities with the pygmy killer whale, the false killer whale and the pilot whales, a study of cytochrome b gene sequences by Richard LeDuc indicated that its closest extant relatives are the snubfin dolphins of the genus Orcaella.[11] Common names English-speaking scientists most often use the term killer whale, although the term orca is increasingly used. Killer whale advocates point out it has a long heritage. Indeed, the genus name Orcinus means of the kingdom of the dead,[12] or belonging to Orcus.[13] Ancient Romans originally applied orca (plural orcae) to these animals, possibly borrowing it from the Greek ὄρυξ, which referred (among other things) to a whale species. Since the 1960s, orca has steadily grown in popularity; both names are now used. The term orca is preferred by some to avoid the negative connotations of killer,[14] and because, being part of the family Delphinidae, the species is more closely related to other dolphins than to whales.[15] According to some authors, the name killer whale would be a mistranslation of the 18th century Spanish name asesina ballenas which means literally whale killer. [16] Basque whalers would have given it such name after observing pods of orcas hunting their own prey. They are sometimes referred to as blackfish, a name used for some whale species, as well. Grampus is a former name for the species, but is now seldom used. This meaning of grampus should not be confused with the Grampus genus, whose only member is Rissos dolphin.[17] Types The three to five types of killer whales may be distinct enough to be considered different races,[18] subspecies, or possibly even species.[19] The IUCN reported in 2008, The taxonomy of this genus is clearly in need of review, and it is likely that O. orca will be split into a number of different species or at least subspecies over the next few years.[2] Although large variation in the ecological distinctiveness of different killer whale groups complicate simple differentiation into types,[20] research off the west coast of Canada and the United States in the 1970s and 1980s identified the following three types: Resident: These are the most commonly sighted of the three populations in the coastal waters of the northeast Pacific. Residents diets consist primarily of fish[21] and sometimes squid, and they live in complex and cohesive family groups called pods.[22] Female residents characteristically have rounded dorsal fin tips that terminate in a sharp corner.[23] They visit the same areas consistently. British Columbia and Washington resident populations are amongst the most intensively studied marine mammals. Researchers have identified and named over 300 killer whales over the past 30 years.[24] Transient: The diets of these whales consist almost exclusively of marine mammals.[21][23] Transients generally travel in small groups, usually of two to six animals, and have less persistent family bonds than residents.[25] Transients vocalize in less variable and less complex dialects.[26] Female transients are characterized by more triangular and pointed dorsal fins than those of residents.[23] The gray or white area around the dorsal fin, known as the saddle patch, often contains some black colouring in residents. However, the saddle patches of transients are solid and uniformly gray.[23] Transients roam widely along the coast; some individuals have been sighted in both southern Alaska and California.[27] Transients are also referred to as Biggs killer whale in honor of Michael Bigg. The term has become increasingly common and may eventually replace the transient label.[28] Offshore: A third population of killer whales in the northeast Pacific was discovered in 1988, when a humpback whale researcher observed them in open water. As their name suggests, they travel far from shore and feed primarily on schooling fish.[29] However, because they have large, scarred and nicked dorsal fins resembling those of mammal-hunting transients, it may be that they also eat mammals and sharks.[30][31] They have mostly been encountered off the west coast of Vancouver Island and near the Queen Charlotte Islands. Offshores typically congregate in groups of 20–75, with occasional sightings of larger groups of up to 200.[32] Currently, little is known about their habits, but they are genetically distinct from residents and transients. Offshores appear to be smaller than the others, and females are characterized by dorsal fin tips that are continuously rounded.[23] Killer whale mother and calf extending their bodies above the water surface, from pectoral fins forward, with ice pack in background Type C killer whales in the Ross Sea: The eye patch slants forward. Transients and residents live in the same areas, but avoid each other.[33][34][35] The name transient originated from the belief that these killer whales were outcasts from larger resident pods. Researchers later discovered transients are not born into resident pods or vice versa. The evolutionary split between the two groups is believed to have begun two million years ago.[36] Genetic data indicate the types have not interbred for up to 10,000 years.[37] Other populations have not been as well studied, although specialized fish-eating and mammal-eating killer whales have been distinguished elsewhere.[38] Separate populations of fish-eating and mammal-eating killer whales have been identified around the United Kingdom.[39][40] Fish-eating killer whales in Alaska[41] and Norway[42] have resident-like social structures, while mammal-eating killer whales in Argentina and the Crozet Islands behave more like transients.[43] Three types have been documented in the Antarctic. Two dwarf species, named Orcinus nanus and Orcinus glacialis, were described during the 1980s by Soviet researchers, but most cetacean researchers are skeptical about their status, and linking these directly to the types described below is difficult.[19]
Posted on: Mon, 04 Nov 2013 20:28:44 +0000
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