Post by DinosaurMichael on Mar 8, 2012 15:11:54 GMT -5
Orca (Killer Whale) - Orcinus orca
The killer whale (Orcinus orca), commonly 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. 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. 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. 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. 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. 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. Killer whales distinctively bear a black back, white chest and sides, and a white patch above and behind the eye. Calves are born with a yellowish or orange tint, which fades to white. Killer whales have a heavy and robust body with a large dorsal fin up to 2 metres (6.6 ft) tall. Behind the fin, they have a dark grey "saddle patch" across the back. Antarctic killer whales may have pale grey to nearly white backs. Adult killer whales are very distinctive and are not usually confused with any other sea creature. When seen from a distance, juveniles can be confused with other cetacean species such as the false killer whale or Risso's dolphin. The killer whale's teeth are very strong and covered in enamel. Its jaws are a powerful gripping apparatus, as the upper teeth fall into the gaps between the lower teeth when the mouth is closed. The front teeth are inclined slightly forward and outward, thus allowing the killer whale to withstand powerful jerking movements from its prey while the middle and back teeth hold it firmly in place. Killer whales are the largest extant members of the dolphin family. Males typically range from 6 to 8 metres (20–26 ft) long and weigh in excess of 6 tonnes (5.9 long tons; 6.6 short tons). Females are smaller, generally ranging from 5 to 7 metres (16–23 ft) and weighing about 3 to 4 tonnes (3.0 to 3.9 long tons; 3.3 to 4.4 short tons). The largest male killer whale on record was 9.8 metres (32 ft), weighing over 10 tonnes (9.8 long tons; 11 short tons), while the largest female was 8.5 metres (28 ft), weighing 7.5 tonnes (7.4 long tons; 8.3 short tons). Calves at birth weigh about 180 kilograms (400 lb) and are about 2.4 metres (7.9 ft) long. The killer whale's large size and strength make it among the fastest marine mammals, able to reach speeds in excess of 30 knots (56 km/h). The skeleton of the killer whale is of the typical delphinid structure but is more robust in all respects. The killer whale's integument, unlike that of most other dolphin species, is characterised by a well-developed dermal layer with a dense network of fascicles of collagen fibers.
Biting Sperm Whale - Brygmophyseter shigensis
Brygmophyseter is an extinct genus of toothed whale in the sperm whale family with one species Brygmophyseter shigensis. When first described, this species was placed in an extinct form genus Scaldicetus of toothed whale, as Scaldicetus shigensis). In 2006, it was transferred to a new genus Naganocetus as ''Naganocetus shigensis'', however later in 2006, it was then moved to Brygmophyseter leaving Naganocetus as a nomen nudum name. The genus name is a combination of the Greek word brygmos, which means "biting" or "gnashing", combined with suffix Physeter, which is the generic name of the living sperm whale, and which is also the Greek word for "blower". This has led to the occasional vernacular term "biting sperm whale" being given to the species in popular culture. The holotype specimen (SFM-0001) was excavated from the Bessho Formation in the Nagano Prefecture in Japan in 1988 by the residents of Shiga-mura with assistance from the staff of the Shiga Fossil Museum. The specimen is nearly complete, and includes a 140 cm (4' 7 ft) long skull. This specimen came from 15-14 million year old sediments. Unlike the extant sperm whale, Physeter macrocephalus, which has teeth in its lower jaw only; Brygmophyseter has 12 functional teeth on each side of the lower jaws and 12 functional teeth on each side of the upper jaws. The holotype specimen is currently on display in the Gunman Museum of Natural History in Japan. The holotype specimen is around 7 metres (23 ft) long. However, in popular culture, Brygmophyseter have been depicted significantly larger in size — up to 12 metres (39 ft) long. Brygmophyseter was likely among the apex predators of its time. It packed a formidable jaws armed with teeth up to 14 cm (5.5 inches) long. It may have employed sonar to track and disorient a prey item in deep waters, like the modern age Sperm Whales. It may also have used its large head to ram a potential opponent during conflict. Brygmophyseter would also have lived in social groups called pods, and probably hunted in packs, like modern age Orcas. Brygmophyseter is assumed to have preyed upon a variety of animals including fish, pinnipeds, giant squid, and other cetaceans. It shall be noted that remains of undetermined mysticeti whales have been found in the same region where the holotype specimen was found, however a predator-prey relationship between Brygmophyseter and these whales have not been inferred in the scientific literature. The shark species C. megalodon was likely a primary predator of the sperm whales. A large number of cetacean bones have been found with large bite marks (deep gashes) in them, which were caused by teeth that belong to C. megalodon.
The killer whale (Orcinus orca), commonly 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. 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. 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. 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. 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. 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. Killer whales distinctively bear a black back, white chest and sides, and a white patch above and behind the eye. Calves are born with a yellowish or orange tint, which fades to white. Killer whales have a heavy and robust body with a large dorsal fin up to 2 metres (6.6 ft) tall. Behind the fin, they have a dark grey "saddle patch" across the back. Antarctic killer whales may have pale grey to nearly white backs. Adult killer whales are very distinctive and are not usually confused with any other sea creature. When seen from a distance, juveniles can be confused with other cetacean species such as the false killer whale or Risso's dolphin. The killer whale's teeth are very strong and covered in enamel. Its jaws are a powerful gripping apparatus, as the upper teeth fall into the gaps between the lower teeth when the mouth is closed. The front teeth are inclined slightly forward and outward, thus allowing the killer whale to withstand powerful jerking movements from its prey while the middle and back teeth hold it firmly in place. Killer whales are the largest extant members of the dolphin family. Males typically range from 6 to 8 metres (20–26 ft) long and weigh in excess of 6 tonnes (5.9 long tons; 6.6 short tons). Females are smaller, generally ranging from 5 to 7 metres (16–23 ft) and weighing about 3 to 4 tonnes (3.0 to 3.9 long tons; 3.3 to 4.4 short tons). The largest male killer whale on record was 9.8 metres (32 ft), weighing over 10 tonnes (9.8 long tons; 11 short tons), while the largest female was 8.5 metres (28 ft), weighing 7.5 tonnes (7.4 long tons; 8.3 short tons). Calves at birth weigh about 180 kilograms (400 lb) and are about 2.4 metres (7.9 ft) long. The killer whale's large size and strength make it among the fastest marine mammals, able to reach speeds in excess of 30 knots (56 km/h). The skeleton of the killer whale is of the typical delphinid structure but is more robust in all respects. The killer whale's integument, unlike that of most other dolphin species, is characterised by a well-developed dermal layer with a dense network of fascicles of collagen fibers.
Biting Sperm Whale - Brygmophyseter shigensis
Brygmophyseter is an extinct genus of toothed whale in the sperm whale family with one species Brygmophyseter shigensis. When first described, this species was placed in an extinct form genus Scaldicetus of toothed whale, as Scaldicetus shigensis). In 2006, it was transferred to a new genus Naganocetus as ''Naganocetus shigensis'', however later in 2006, it was then moved to Brygmophyseter leaving Naganocetus as a nomen nudum name. The genus name is a combination of the Greek word brygmos, which means "biting" or "gnashing", combined with suffix Physeter, which is the generic name of the living sperm whale, and which is also the Greek word for "blower". This has led to the occasional vernacular term "biting sperm whale" being given to the species in popular culture. The holotype specimen (SFM-0001) was excavated from the Bessho Formation in the Nagano Prefecture in Japan in 1988 by the residents of Shiga-mura with assistance from the staff of the Shiga Fossil Museum. The specimen is nearly complete, and includes a 140 cm (4' 7 ft) long skull. This specimen came from 15-14 million year old sediments. Unlike the extant sperm whale, Physeter macrocephalus, which has teeth in its lower jaw only; Brygmophyseter has 12 functional teeth on each side of the lower jaws and 12 functional teeth on each side of the upper jaws. The holotype specimen is currently on display in the Gunman Museum of Natural History in Japan. The holotype specimen is around 7 metres (23 ft) long. However, in popular culture, Brygmophyseter have been depicted significantly larger in size — up to 12 metres (39 ft) long. Brygmophyseter was likely among the apex predators of its time. It packed a formidable jaws armed with teeth up to 14 cm (5.5 inches) long. It may have employed sonar to track and disorient a prey item in deep waters, like the modern age Sperm Whales. It may also have used its large head to ram a potential opponent during conflict. Brygmophyseter would also have lived in social groups called pods, and probably hunted in packs, like modern age Orcas. Brygmophyseter is assumed to have preyed upon a variety of animals including fish, pinnipeds, giant squid, and other cetaceans. It shall be noted that remains of undetermined mysticeti whales have been found in the same region where the holotype specimen was found, however a predator-prey relationship between Brygmophyseter and these whales have not been inferred in the scientific literature. The shark species C. megalodon was likely a primary predator of the sperm whales. A large number of cetacean bones have been found with large bite marks (deep gashes) in them, which were caused by teeth that belong to C. megalodon.
